Precipitated silica and method for producing the same

Abstract

The invention discloses precipitated silica with a large median particle size, which is used as a reinforcing filler in elastomer compositions, and a method for its manufacture.

Description

Technical Field

[0001] This invention relates to precipitated silica and to a method for its manufacture. Background Technology

[0002] The use of precipitated silica as a reinforcing filler in polymer compositions is known. Specifically, the use of precipitated silica as a reinforcing filler in elastomer compositions is known. This use places high demands on the filler to be easily and effectively incorporated and dispersed in the elastomer composition, and typically in combination with a coupling agent to form chemical bonds with one or more elastomers, resulting in a high and uniform reinforcement of the elastomer composition. Precipitated silica is typically used to improve the mechanical properties and wear resistance of elastomer compositions. In practice, there is always a need for precipitated silica capable of providing a balance between conflicting properties such as abrasion resistance and / or polymer reinforcement, while also providing reduced energy dissipation characteristics (which in turn provide reduced heat buildup). Summary of the Invention

[0003] A first object of the present invention is to provide a novel precipitated silica that, when effectively incorporated into polymer compositions, provides a balance of improved performance properties. A second object of the present invention is a method for manufacturing the precipitated silica. Another object of the present invention is to provide an elastomer composition comprising the precipitated silica as a reinforcing filler. These objects are achieved by the precipitated silica of the present invention, as defined in detail in the following description and in the claims and examples.

[0004] It has been found that good mechanical properties and reduced energy dissipation (and thus heat buildup) of elastomer compositions can be obtained by using precipitated silica containing at least 0.1 mol% of at least one metal M (selected from the group consisting of elements of Groups 3, 4 and 5) and having a large median particle size d50 relative to its CTAB surface area as measured by centrifugal sedimentation.

[0005] Precipitated silica containing transition metals (e.g., Ti, Zr, V, Sc) has been previously described, for example, in US 7070749 (which discloses precipitated silica doped with foreign atoms for papermaking applications). US 7070749 does not disclose the size of silica particles as measured by centrifugal sedimentation in a disc centrifuge.

[0006] FR 2997405 discloses a composition comprising Ti-doped precipitated silica combined with a selected combination of hypophosphonate / phosphonate coupling agents. The particle size of the precipitated silica disclosed in FR 2997405 does not meet the standard represented by formula (I) below. Detailed Implementation

[0007] The precipitated silica of the present invention is characterized by:

[0008] -From 70 to 350m 2 CTAB surface area S within the range of / g CTAB ;

[0009] - At least 0.1 mol% of W M At least one metal M, selected from the group consisting of elements of groups 3, 4, and 5; and

[0010] -The median particle size d50, measured by centrifugal sedimentation, makes (I):

[0011] |d50|≥183×|R ION |×|W M |-0.67×|S CTAB |+233 (I)

[0012] in:

[0013] |d50| represents the median particle size d50 measured by centrifugation and is expressed in nm; |R ION | Represents the ionic radius of the metal M, expressed in nm; |S CTAB | Represents the surface area S of the CTAB CTAB The value, in m 2 / g indicates; and |W M | Represents the molar percentage of metal M, W M The value.

[0014] In this specification, the terms “silicon dioxide” and “precipitated silicon dioxide” are used as synonyms.

[0015] In this specification, the numerical range defined by the phrase "from a to b" indicates a numerical range including the endpoints a and b.

[0016] The range of values ​​defined by the statement "a is at least b" indicates the range in which a is equal to or greater than b.

[0017] To avoid any ambiguity, the symbol “×” in formula (I) represents a multiplication sign, so that the expression “a×b” means a multiplied by b.

[0018] CTAB surface area S CTAB It is a measure of the external specific surface area, determined by measuring the amount of N-hexadecyl-N,N,N-trimethylammonium bromide adsorbed on a silica surface at a given pH.

[0019] CTAB surface area S CTAB It is at least 70m2 / g, typically at least 80m 2 / g, or even at least 90m 2 / g. CTAB surface area S CTAB It can be greater than 100m 2 / g. CTAB surface area S CTAB It can even be greater than 120m 2 / g, greater than 140m 2 / g, possibly even greater than 150m 2 / g.

[0020] CTAB surface area not exceeding 350m² 2 / g, typically it does not exceed 320m 2 / g. CTAB surface area S CTAB It can be below 300m 2 / g.

[0021] For elastomer reinforcement applications, the CTAB surface area S CTAB The favorable range is from 70 to 300 meters. 2 / g, from 80 to 300m 2 / g, from 120 to 300m 2 / g, from 140 to 300m 2 / g, even from 145 to 300m 2 / g, also from 130 to 280m 2 / g.

[0022] The BET surface area S of silicon dioxide of the present invention BET No special restrictions apply. BET surface area S BET Typically at least 80m 2 / g, at least 100m 2 / g, at least 140m 2 / g, at least 160m 2 / g, or even at least 170m 2 / g, at least 180m 2 / g, and even at least 200m 2 / g. BET surface area S BET Up to 400m 2 / g, even as high as 450m 2 / g.

[0023] The silicon dioxide of this invention comprises at least one metal M, selected from the group consisting of elements of Groups 3, 4, and 5 according to the IUPAC nomenclature. For the avoidance of doubt, Group 3 is herein considered to consist of the elements Sc, Y, La, and Ac.

[0024] Metal M is preferably selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, and Ta. More preferably, metal M is selected from the group consisting of Sc, Y, Ti, Zr, and Hf. Advantageously, metal M is selected from the group consisting of Y, Ti, and Zr. Metal M may advantageously be Zr.

[0025] Metal M in an amount of at least 0.1 mol% W M Existence. Throughout this article, the amount W of metal M is... M It is defined as the amount of at least one element M in moles relative to silicon dioxide.

[0026] W M Preferably, it is at least 0.2 mol%, or even at least 0.3 mol%. Advantageously, W M It is in the range of 0.1 to 7.0 mol%, typically from 0.2 to 5.0 mol%, and even from 0.3 to 3.0 mol%.

[0027] When metal M is Zr, W M It is conveniently available in the range of 0.2 to 3.5 mol%, even from 0.3 to 3.0 mol%, and from 0.4 to 2.5 mol%.

[0028] It should be understood that the silicon dioxide of the present invention may contain elements other than metal M, and noteworthy non-limiting examples are, for example, Mg, Ca, Al or Zn.

[0029] An important feature of the silicon dioxide of this invention is that for a given S CTAB The median particle size (particle diameter) d50 is large. In particular, it has been found that the median particle size of the silica of the present invention increases with the amount of metal M in the silica and its ionic radius.

[0030] It has been found that the median particle size d50 of the silica of the present invention is related to the amount W of metal M. M Its ionic radius R ION and CTAB surface area S CTAB Related to formula (I):

[0031] |d50|≥183×|R ION |×|W M |-0.67×|S CTAB |+233 (I).

[0032] In formula (I), |d50| represents the median particle size d50 measured by centrifugal sedimentation and is expressed in nm. |d50| is a dimensionless number. For example, if the value of d50 measured by centrifugal sedimentation is 100 nm, then |d50| is 100.

[0033] In formula (I), |R ION | represents the ionic radius of metal M, expressed in nm, at its most representative higher coordination number and oxidation state. For example, if the ionic radius is 0.072 nm, then |R ION It is 0.072.

[0034] The ionic radius values ​​are taken from R.Shannon, "Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides", Acta Crystallographica, A32, 751-767 (1976), and are reported in Table 1.

[0035] Table 1

[0036] Metal M (oxidation state, coordination number) <![CDATA[R ION (nm)]]> Sc(III,8) 0.084 Y(III, 8) 0.102 La(III, 8) 0.116 Ac(III, 6) 0.112 Ti(IV,6) 0.060 Zr(IV, 6) 0.072 Hf(IV, 6) 0.072 V(V, 5) 0.046 Ta(V, 8) 0.074 Nb(V, 8) 0.074

[0037] In formula (I), the percentage amount W of metal M is... M The value of W M | is a dimensionless number. For example, if the amount of metal M relative to the weight of silicon dioxide is 0.3 mol%, then |W M It is 0.3.

[0038] When more than one metal M is present in precipitated silica, |R in (I) ION |×|W M The value of | corresponds to |R| for each metal. ION |×|W M The sum of |

[0039] In formula (I), |S CTAB | Represents the surface area S of CTAB CTAB The value, in m 2 / g represents. |S CTAB | is a dimensionless number. For example, if S CTAB The measured value is 200m 2 / g, then |S CTAB | is 200.

[0040] From 70 to 350m 2 / g of CTAB surface area S CTAB Within the scope of this invention, the silicon dioxide is characterized by a median particle size d50 that is typically greater than 30 nm, or even greater than 50 nm.

[0041] The d50 value of the silicon dioxide of the present invention typically does not exceed 300 nm, and more typically it does not exceed 250 nm.

[0042] The precipitated silica of this invention is typically characterized by a wide particle size distribution. The term "particle" is used herein to refer to an aggregate of primary silica particles. The term "particle" is also used to refer to the smallest aggregate of primary silica particles that can be broken down by mechanical action. In other words, the term "particle" refers to an indivisible aggregate of primary particles.

[0043] The parameter Ld, determined by centrifugal sedimentation in a disc centrifuge, is described in detail below to characterize the particle size distribution width. Ld is defined as follows:

[0044] Ld=(d84-d16) / d50

[0045] Where dn is the particle diameter, and n% of the total measured mass is found to be below this particle diameter. Ld is a dimensionless number. The particle size distribution width Ld is calculated on the cumulative particle size curve. For example, d50 represents the particle diameter, and 50% of the total particle mass is found to be below (and above) this particle diameter. Therefore, d50 represents the median particle size for a given distribution, where the term "size" in this context is intended to mean "diameter".

[0046] The particle size distribution width Ld is at least 1.2, typically at least 1.4, or even at least 1.5. The particle size distribution width Ld is not greater than 4.0, typically not greater than 3.5.

[0047] Advantageously, the particle size distribution width Ld of the silica of the present invention can be in the range of 1.2 to 3.5, or even in the range of 1.4 to 3.0. The particle size distribution width Ld of the silica of the present invention can be in the range of 1.5 to 2.8, preferably from 1.6 to 2.5.

[0048] A second objective of this invention is a method for preparing the precipitated silica of this invention, the method comprising:

[0049] (i) Provide starting solutions with a pH ranging from 2.00 to 5.00.

[0050] (ii) Simultaneously, silicates and acids are added to the starting solution to maintain the pH of the reaction medium in the range of 2.00 to 5.00.

[0051] (iii) Stop adding the acid and the silicate and add a base to the reaction medium to raise the pH of the reaction medium to a value from 7.00 to 10.00.

[0052] (iv) Simultaneously add at least one compound of metal M, a silicate, and an acid to the reaction medium, such that the pH of the reaction medium is maintained in the range of 7.00 to 10.00.

[0053] (v) Stop adding the silicate and the compound of at least one metal M, while continuing to add the acid to the reaction medium to achieve a pH of less than 6.00 and obtain a suspension of precipitated silica.

[0054] The term "base" is used herein to refer to one or more bases that may be added during the process of the method of the invention, and includes the group consisting of silicates as defined below. Any base may be used in the method. Notable non-limiting examples of suitable bases besides silicates are, for example, alkali metal hydroxides and ammonia.

[0055] The term "silicate" is used herein to refer to one or more silicates that may be added during the process of the method of the invention. Silicates are typically selected from the group consisting of alkali metal silicates. Advantageously, silicates are selected from the group consisting of sodium silicate and potassium silicate. Silicates can be in any known form, such as metasilicates or disilicates.

[0056] When sodium silicate is used, the SiO2 / Na2O weight ratio is typically from 2.0 to 4.0, particularly from 2.4 to 3.9, for example from 3.1 to 3.8.

[0057] The concentration of silicate (expressed as SiO2) can be from 3.9 wt% to 25.0 wt%, for example from 5.6 wt% to 23.0 wt%, particularly from 5.6 wt% to 20.7 wt%.

[0058] The term "acid" is used herein to refer to one or more acids that may be added during the process of the method of the present invention. Any acid may be used in the method. Inorganic acids, such as sulfuric acid, nitric acid, phosphoric acid, or hydrochloric acid, or organic acids, such as carboxylic acids, for example acetic acid, formic acid, or carbonic acid, are commonly used.

[0059] The acid can be added to the reaction medium in diluted or concentrated form. Different concentrations of the same acid can be used at different stages of the method. Preferably, the acid is sulfuric acid.

[0060] In a preferred embodiment of the method, sulfuric acid and sodium silicate are used in all stages of the method. Preferably, the same sodium silicate, i.e., sodium silicate with the same concentration expressed as SiO2, is used in all stages of the method.

[0061] In step (i) of the method, a starting solution having a pH from 2.00 to 5.00 is provided in the reaction vessel. The starting solution is an aqueous solution, and the term "aqueous" indicates that the solvent is water.

[0062] Preferably, the starting solution has a pH of 2.50 to 5.00, especially from 3.00 to 4.50, for example from 3.50 to 4.50.

[0063] The starting solution can be obtained by adding acid to water to achieve the pH value as detailed above.

[0064] Alternatively, the starting solution may contain silicates. In this case, the starting solution can be obtained by adding acid to a mixture of water and silicates to achieve a pH from 2.00 to 5.00.

[0065] The starting solution can also be prepared by adding an acid to a solution containing pre-formed silica particles at a pH below 7.00 to obtain a pH value from 2.00 to 5.00, preferably from 2.50 to 5.00, and especially from 3.00 to 4.50 (e.g. from 3.50 to 4.50).

[0066] The starting solution in step (i) may or may not contain an electrolyte. Preferably, the starting solution in step (i) contains an electrolyte.

[0067] The term "electrolyte" is used herein in its generally accepted sense, that is, to refer to any ionic or molecular substance that decomposes or dissociates in solution to form ions or charged particles. The term "electrolyte" is used herein to indicate that one or more electrolytes may be present. Electrolytes such as salts of alkali metals and alkaline earth metals may be mentioned. Advantageously, the electrolyte used in the starting solution is a salt of the metal of the starting silicate and the acid used in the method. Notable examples are, for example, sodium chloride in the case of the reaction of sodium silicate with hydrochloric acid, or preferably, sodium sulfate in the case of the reaction of sodium silicate with sulfuric acid.

[0068] Preferably, when sodium sulfate is used as the electrolyte in step (i), its concentration in the starting solution is from 8 g / L to 40 g / L, especially from 10 g / L to 35 g / L, for example from 13 g / L to 30 g / L.

[0069] Step (ii) of the method involves the simultaneous addition of an acid and a silicate to the starting solution. The rate of addition of the acid and silicate during step (ii) is controlled such that the pH of the reaction medium is maintained in the range of 2.00 to 5.00. The pH of the reaction medium is preferably maintained in the range of 2.50 to 5.00, particularly in the range of 3.00 to 5.00, for example, in the range of 3.20 to 4.80.

[0070] Advantageously, the addition is carried out simultaneously in step (ii) in such a way that the pH of the reaction medium is always equal to (within ±0.20 pH units) the pH reached at the end of step (i).

[0071] Preferably, step (ii) consists of the simultaneous addition of the acid and silicate as detailed above.

[0072] In one embodiment of the method of the present invention, an intermediate step (ii') may be performed between step (i) and step (ii), wherein silicates and acids are added to the starting solution such that the pH of the reaction medium is maintained in the range of 2.00 to 9.50. For all or only part of step (ii'), the addition of silicates and acids may be simultaneous. Step (ii') typically lasts for 1 to 10 minutes, preferably 2 to 8 minutes, prior to the start of step (ii).

[0073] Next, in step (iii), the addition of acid and silicate is stopped, and alkali is added to the reaction medium. The addition of alkali is stopped when the pH of the reaction medium reaches a value from 7.00 to 10.00, preferably from 7.50 to 9.50.

[0074] In a first embodiment of the method, the base is a silicate. Therefore, in step (iii), the addition of acid is stopped while silicate is continued to be added to the reaction medium until the pH reaches a value from 7.00 to 10.00, preferably from 7.50 to 9.50.

[0075] In a second embodiment of the method, the base is different from silicates and is selected from the group consisting of alkali metal hydroxides, preferably sodium hydroxide or potassium hydroxide. When sodium silicate is used in the method, sodium hydroxide is a preferred base.

[0076] Therefore, in this second embodiment of the method, in step (iii), the addition of acid and silicate is stopped, and a base different from silicate is added to the reaction medium until the pH reaches from 7.00 to 10.00, preferably from 7.50 to 9.50.

[0077] At the end of step (iii), i.e., after the addition of alkali has been stopped, it is advantageous to perform a maturing step of the reaction medium. This step is preferably carried out at the pH obtained at the end of step (iii). The maturing step can be carried out while the reaction medium is being stirred. The maturing step is preferably carried out over a period of 2 to 45 minutes, particularly 5 to 25 minutes, with stirring of the reaction medium. Preferably, the maturing step does not involve the addition of any acid or silicate.

[0078] After step (iii) and optional ripening step, at least one metal M compound, acid and silicate are added simultaneously, such that the pH of the reaction medium is maintained in the range of 7.00 to 10.00, preferably from 7.50 to 9.50.

[0079] Typically, at least one metal M compound, acid, and silicate are added simultaneously (step (iv)) in such a way that the pH of the reaction medium is maintained equal to the pH reached at the end of the previous step, i.e., step (iii) (within ±0.20 pH units).

[0080] It should be noted that the method of the present invention may include additional steps. For example, between step (iii) and step (iv), and particularly between the optional ripening step after step (iii) and step (iv), an acid may be added to the reaction medium. After the addition of this acid, the pH of the reaction medium should be maintained in the range of 7.00 to 9.50, preferably in the range of 7.50 to 9.50.

[0081] In step (v), the addition of the silicate and at least one metal M compound is stopped, while acid continues to be added to the reaction medium to obtain a pH value less than 6.00, preferably from 3.00 to 5.50, and particularly from 3.00 to 5.00. A suspension of precipitated silica is obtained in the reaction vessel.

[0082] At the end of step (v), and therefore after the addition of acid to the reaction medium is stopped, a ripening step can advantageously be performed. This ripening step can be carried out at the same pH obtained at the end of step (v) and at the same time conditions as those described above for the ripening step which may optionally be performed between steps (iii) and (iv) of the method.

[0083] During step (iv), i.e., during the simultaneous addition of acid and silicate to a reaction medium with a pH range of 7.00 to 10.00, a compound of at least one metal M is metered into the reaction medium. The addition of the compound of at least one metal M may be metered into the reaction medium over the entire duration of step (iv), i.e., at the same time as the addition of acid and silicate. Alternatively, it may be metered only during a portion of step (iv), for example, only after the first simultaneous addition of acid and silicate has occurred. Typically, the compound of at least one metal M is added to the reaction medium in the form of a solution (typically an aqueous solution). All of the compounds of at least one metal M are added during step (iv).

[0084] In the method of this invention, any compound of metal M can be used, provided that it is soluble in water, and particularly soluble at pH values ​​in the range of 7.00 to 10.00. Notable examples of suitable compounds include, but are not limited to, chlorides, sulfates, oxysulfates, or nitrates of metal M. The compound is generally selected from the group consisting of sulfates or oxysulfates. The compound of metal M is typically added to the reaction medium in the form of a solution (typically an aqueous solution).

[0085] Calculate the amount of at least one metal M compound added to the reaction medium during step (iv) such that the amount of metal M in the final product is W. M It is at least 0.1 mol%.

[0086] The reaction vessel in which the entire reaction of silicates and acids takes place is usually equipped with appropriate stirring and heating equipment.

[0087] The entire reaction of silicate with acid (steps (i) to (v)) is generally carried out at a temperature ranging from 40°C to 97°C, particularly from 60°C to 95°C, preferably from 80°C to 95°C, and more preferably from 85°C to 95°C.

[0088] According to a variation of the invention, the entire reaction of silicate with acid is carried out at a constant temperature, typically from 40°C to 97°C, particularly from 80°C to 95°C, and even from 85°C to 95°C.

[0089] According to another variant of the invention, the temperature at the end of the reaction is higher than the temperature at the beginning of the reaction: therefore, the temperature at the beginning of the reaction (e.g., during steps (i) to (iii)) is preferably maintained in the range of 40°C to 85°C, and then the temperature is raised, preferably to a value in the range of 80°C to 95°C, or even from 85°C to 95°C, and the temperature is maintained at that value (e.g., during steps (iv) and (v)) until the reaction ends.

[0090] Different parameters of the method, such as temperature, pH of the reaction medium, amount of electrolyte present in step (i), and amount of at least one metal M compound, can be varied to obtain precipitated silica with the required values ​​of CTAB specific surface area and amount of metal M.

[0091] At the end of the steps described above, a suspension of precipitated silica is obtained, which is then separated (liquid / solid separation). This method typically includes another step (vi) of filtering the suspension and drying the precipitated silica.

[0092] The separation performed in the preparation method according to the invention typically includes filtration followed by washing, if necessary. Filtration is carried out by any suitable method, such as by a belt filter, a rotary filter, a vacuum filter, or, preferably, a filter press.

[0093] The filter cake is then subjected to a liquefaction process. The term "liquefaction" here is intended to refer to the process in which a solid (i.e., the filter cake) is transformed into a fluid substance. After the liquefaction step, the filter cake is in a flowable, fluid form and the precipitated silica is in a suspension.

[0094] The liquefaction step may include mechanical treatment that results in a reduction in the granulometry of silica in the suspension. This mechanical treatment can be performed by passing the filter cake through a high-shear mixer, a colloid mill, or a ball mill. Alternatively, the liquefaction step may be performed by subjecting the filter cake to chemical treatment through the addition of, for example, an acid or an aluminum compound (e.g., sodium aluminate). Still alternatively, the liquefaction step may include both mechanical treatment and chemical treatment.

[0095] The suspension of precipitated silica obtained after the liquefaction step is then preferably dried.

[0096] Drying can be carried out by means known in the art. Preferably, drying is performed by atomization. For this purpose, any type of suitable atomizer can be used, particularly turbine, nozzle, hydraulic, or two-fluid spray dryers.

[0097] When a nozzle spray dryer is used for the drying operation, the precipitated silica that can be obtained is typically in the form of substantially spherical beads. Following this drying operation, the recovered product may optionally be subjected to a milling or micronization step; the precipitated silica that can then be obtained is typically in the form of powder.

[0098] When a turbine spray dryer is used for drying, the precipitated silica can then be obtained in powder form.

[0099] Finally, the dried, ground, or micronized product, as previously indicated, may optionally undergo an agglomeration step, which includes, for example, direct compression, wet granulation (i.e., using a binder such as water, silica suspension, etc.), extrusion, or, preferably, dry pressing.

[0100] The precipitated silica obtained through this agglomeration step is typically in the form of particles.

[0101] The precipitated silica of the present invention can be used in a variety of applications, such as as an absorbent for active materials (specifically as a carrier for liquids, especially for food, such as vitamins (vitamin E or choline chloride)), as a viscosity modifier, conditioning agent or anti-caking agent, or as an additive in toothpaste, concrete or paper.

[0102] The silica of this invention can be used as a catalyst or catalyst support. Therefore, the object of this invention is a catalyst or catalyst support comprising, or even composed of, the precipitated silica of this invention.

[0103] The silica of this invention can also be used to manufacture thermal insulation materials or to prepare resorcinol-formaldehyde / silica composites. The silica of this invention can also be conveniently used as an absorbent, for example, in the preparation of personal care or baby care products, such as diapers.

[0104] The precipitated silica of the present invention is particularly advantageous as a filler in polymer compositions.

[0105] Therefore, another object of the present invention is a composition comprising silica as defined above and at least one polymer. When referring to the polymer in the composition, the phrase "at least one" is used herein to indicate that one or more polymers of each type may be present in the composition.

[0106] The term "copolymer" is used herein to refer to a polymer comprising repeating units derived from at least two monomer units with different properties.

[0107] At least one polymer may be selected from thermosetting polymers and thermoplastic polymers. Notable non-limiting examples of thermosetting polymers include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenolic resins, epoxy acrylate resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, and cyanate ester resins.

[0108] Notable non-limiting examples of suitable thermoplastic polymers include styrene-based polymers such as polystyrene, (meth)acrylate / styrene copolymers, acrylonitrile / styrene copolymers, styrene / maleic anhydride copolymers, and ABS; acrylic polymers such as polymethyl methacrylate; polycarbonates; polyamides; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyphenylene ether; polysulfone; polyaryl ether ketone; polyphenylene sulfide; thermoplastic polyurethanes; polyolefins such as polyethylene, polypropylene, polybutene, poly-4-methylpentene, ethylene / propylene copolymers, and ethylene / α-olefin copolymers; copolymers of α-olefins and various monomers such as ethylene / vinyl acetate copolymers, ethylene / (meth)acrylate copolymers, ethylene / maleic anhydride copolymers, and ethylene / acrylic acid copolymers; and aliphatic polyesters such as polylactic acid, polycaprolactone, and aliphatic diol / aliphatic dicarboxylic acid copolymers.

[0109] The silica of the present invention can be advantageously used as a reinforcing filler in elastomer compositions. Therefore, a preferred object of the present invention is a composition comprising the silica of the present invention and one or more elastomers, which preferably exhibit at least one glass transition temperature between -150°C and +300°C (e.g., between -150°C and +20°C).

[0110] Notable, non-limiting examples of suitable elastomers are diene elastomers. For example, elastomers derived from aliphatic or aromatic monomers containing at least one degree of unsaturation can be used, such as, in particular, ethylene, propylene, butadiene, isoprene, styrene, acrylonitrile, isobutylene, or vinyl acetate, polybutyl acrylate, or mixtures thereof. Also mentioned are functionalized elastomers, which are elastomers functionalized by chemical groups (e.g., by functional groups capable of reacting with silica surfaces) positioned along the macromolecular chain and / or at one or more of its ends, as well as halogenated polymers. Polyamides, ethylene homopolymers and copolymers, and propylene homopolymers and copolymers may also be mentioned.

[0111] Among diene elastomers that may be mentioned are, for example, polybutadiene (BR), polyisoprene (IR), butadiene copolymers, isoprene copolymers, or mixtures thereof, and in particular styrene / butadiene copolymers (SBR, especially ESBR (emulsion) or SSBR (solution)), isoprene / butadiene copolymers (BIR), isoprene / styrene copolymers (SIR), isoprene / butadiene / styrene copolymers (SBIR), ethylene / propylene / diene terpolymers (EPDM), and related functionalized polymers (e.g., those having side polar groups or polar groups at the chain ends that can interact with silica).

[0112] Also worth mentioning are natural rubber (NR) and epoxidized natural rubber (ENR).

[0113] The polymer composition can be vulcanized with sulfur or crosslinked with sulfur, especially with peroxides or other crosslinking systems (e.g., diamines or phenolic resins).

[0114] In general, these polymer compositions additionally contain at least one (silica / polymer) coupling agent and / or at least one masking agent; they may also contain antioxidants among others.

[0115] Non-limiting examples of suitable coupling agents are, for example, "symmetrical" or "asymmetric" silane polysulfides; more particularly, bis((C1-C4)alkoxy(C1-C4)alkylsilyl(C1-C4)alkyl) polysulfides (especially disulfides, trisulfides, or tetrasulfides), such as bis(3-(trimethoxysilyl)propyl) polysulfides or bis(3-(triethoxysilyl)propyl) polysulfides, such as triethoxysilylpropyltetrasulfide. Monoethoxydimethylsilylpropyltetrasulfide may also be mentioned. Silanes containing masked or free thiol functional groups may also be mentioned.

[0116] The coupling agent can be pre-grafted onto the polymer. It can also be used in a free state (i.e., without pre-grafting) or grafted onto the surface of silica. The same applies to optional masking agents.

[0117] The coupling agent can optionally be combined with a suitable "coupling activator," that is, a compound that, when mixed with the coupling agent, increases the effectiveness of the coupling agent.

[0118] The weight ratio of silica in the polymer composition of the present invention can vary over a fairly wide range. It typically represents an amount of one or more polymers ranging from 10% to 200%, particularly from 20% to 150%, especially from 20% to 80% (e.g., from 30% to 70%) or from 80% to 120% (e.g., from 90% to 110%).

[0119] The silica according to the invention can advantageously constitute all of the reinforcing inorganic filler and even all of the reinforcing filler in the polymer composition.

[0120] The silica of the present invention can optionally be combined with at least one other reinforcing filler, such as highly dispersible silica, such as... 1165MP 1115MP Premium 200MP or 1085GR (commercially available from Solvay), or another reinforcing inorganic filler, such as nanoclay or alumina. Alternatively, the silica of this invention can be combined with an organic reinforcing filler, such as carbon black nanotubes, graphene, etc.

[0121] The silica according to the invention then preferably constitutes at least 40% by weight, and indeed even at least 50% by weight, of the total amount of reinforcing filler.

[0122] The compositions comprising the precipitated silica of the present invention can be used to manufacture a variety of articles. Non-limiting examples of articles comprising at least one of the above polymer compositions include, for example, shoe soles, floor coverings, gas barriers, flame retardant materials, and engineered components such as cable rollers, seals for household appliances, seals for liquid or gas pipelines, brake system seals, pipes (flexible), sheaths (especially cable sheaths), cables, engine mounts, battery separators, conveyor belts, or transmission belts.

[0123] In a preferred embodiment of the invention, the composition comprising the precipitated silica of the invention is used to manufacture tires or tire components.

[0124] If any disclosure of any patent, patent application, or publication incorporated herein by reference conflicts with the description of this application to the extent that it may lead to ambiguity in terminology, this specification shall take precedence.

[0125] Analytical methods

[0126] The physicochemical properties of the precipitated silica of the present invention were determined using the methods described below.

[0127] Determination of CTAB surface area

[0128] According to standard NF ISO 5794-1, Appendix G determines the CTAB surface area (S). CTAB )value.

[0129] Determination of BET surface area

[0130] The BET surface area (S) is determined according to the Brunauer-Emmett-Teller method detailed in standard NF ISO 5794-1, Annex E (June 2010). BET The following adjustments were made: the sample was pre-dried at 160℃±10℃; the partial pressure P / P used for measurement was... 0 It is between 0.05 and 0.2.

[0131] Particle size distribution and particle size were determined by centrifugal sedimentation in a disc centrifuge (CPS Corporation).

[0132] The values ​​of d50, d16, d84, and Ld were determined by centrifugal sedimentation in a disc centrifuge using a CPS DC24000UHR centrifugal optical sedimentation apparatus sold by CPS Instruments. This instrument is equipped with operating software (version 11g) supplied with the device.

[0133] Instruments used: For measurement purposes, the following materials and products were used: Ultrasonic system: 1500W generator model Sonics Vibracell VC1500 / VCX1500 equipped with a 19mm probe (converter: CV154 + booster (part number: BHNVC21) + 19mm probe (part number: 630-0208)).

[0134] An analytical balance with an accuracy of 0.1 mg (e.g., Mettler AE260); syringes: 1.0 mL and 2.0 mL, with 20 g needles; 50 mL tall glass beakers (SCHOTT DURAN: 38 mm diameter, 78 mm height); a magnetic stirrer with a 2 cm stirring rod; and a container for an ice bath during sonication.

[0135] Chemicals: Deionized water; 96% ethanol; 99% sucrose; dodecane, all from Merck; PVC reference standard from CPS Instrument Inc.; the peak values ​​of the reference standard used should be between 200 and 600 nm (e.g., 237 nm).

[0136] Preparation of a disc centrifuge

[0137] For measurements, the following parameters were established. For calibration standard parameters, information on the PVC reference provided by the supplier was used.

[0138]

[0139] × cps = centipoise

[0140] System Configuration

[0141] The measurement wavelength was set to 405nm. The following runtime option parameters were established:

[0142]

[0143] All other software options remain as set by the instrument manufacturer.

[0144] Preparation of a disc centrifuge

[0145] The centrifuge disc was rotated at 24,000 rpm for 30 minutes. The density gradient of sucrose (CAS n°57-50-1) was prepared as follows:

[0146] Prepare an aqueous solution of 24% wt% sucrose in a 50 mL beaker. Prepare an aqueous solution of 8% wt% sucrose in a 50 mL beaker. Once both solutions have been homogenized separately, take a sample from each solution using a 2 mL syringe and inject it into a rotating dish in the following order:

[0147] Sample 1: 1.8 mL of 24 wt% solution

[0148] Sample 2: 1.6 mL of 24 wt% solution + 0.2 mL of 8 wt% solution

[0149] Sample 3: 1.4 mL of 24 wt% solution + 0.4 mL of 8 wt% solution

[0150] Sample 4: 1.2 mL of 24 wt% solution + 0.6 mL of 8 wt% solution

[0151] Sample 5: 1.0 mL of 24 wt% solution + 0.8 mL of 8 wt% solution

[0152] Sample 6: 0.8 mL of 24 wt% solution + 1.0 mL of 8 wt% solution

[0153] Sample 7: 0.6 mL of 24 wt% solution + 1.2 mL of 8 wt% solution

[0154] Sample 8: 0.4 mL of 24 wt% solution + 1.4 mL of 8 wt% solution

[0155] Sample 9: 0.2 mL of 24 wt% solution + 1.6 mL of 8 wt% solution

[0156] Sample 10: 1.8 mL of 8 wt% solution

[0157] Before each injection into the pan, homogenize the two solutions in the syringe by drawing in about 0.2 mL of air and then simply stirring manually for a few seconds (to ensure no liquid is lost).

[0158] These injections, totaling 18 mL, were used to generate a density gradient that could be used to eliminate some instability that might occur during the injection of the sample to be measured. To prevent the density gradient from evaporating, 1 mL of dodecane was added to the rotating disk using a 2 mL syringe. The disk was then kept rotating at 24,000 rpm for 60 min prior to any first measurement.

[0159] Sample preparation

[0160] Weigh 3.2 g of silica into a 50 mL tall glass beaker (SCHOTT DURAN: 38 mm in diameter, 78 mm in height) and add 40 mL of deionized water to obtain an 8 wt% silica suspension. Stir the suspension with a magnetic stirrer (for at least 20 seconds), then place the beaker in a crystallization dish containing ice and cold water. Remove the magnetic stirrer and place the crystallization dish under an ultrasonic probe positioned 1 cm from the bottom of the beaker. Set the ultrasonic probe to 56% of its maximum amplitude and run for 8 minutes. At the end of the ultrasonic treatment, place the beaker back on a magnetic stirrer using a 2 cm magnetic stirring rod at a minimum of 500 rpm until sampling.

[0161] The ultrasonic probe should be in proper operating conditions. The following checks must be performed, and a new probe should be used in case of negative results: visual inspection of the physical integrity of the probe tip (roughness depth less than 2 mm measured with precision calipers); commercial silica... The measured d50 of 1165MP should be 93nm ± 3nm.

[0162] analyze

[0163] Before analyzing each sample, the calibration standard is recorded. In each case, 0.1 mL of a PVC standard provided by CPS Instruments, whose characteristics are pre-entered into the software, is injected. Importantly, the measurement is initiated in the software simultaneously with this first injection of the PVC standard. By ensuring that the measurement is initiated at the same time as the injection, confirmation from the instrument should have been received before injecting 100 μL of the pre-sonicated sample.

[0164] These injections were performed using two clean 1 mL syringes.

[0165] At the end of the measurement, the endpoint is reached where the time required for all smaller diameter particles (configured to 0.02 μm in the software) to settle is obtained, yielding the ratio for each diameter category. The resulting curve is called the aggregate size distribution.

[0166] result

[0167] The values ​​d50, d16, d84, and Ld are based on distributions plotted on a linear scale. Integrating the particle size distribution function of diameter allows for the acquisition of a "cumulative" distribution, that is, the total mass of particles between the minimum diameter and the diameter of interest.

[0168] d50: The diameter below and above 50% of the total mass. d50 is referred to as the median size, or diameter, of silica particles.

[0169] d84: The diameter below which 84% of the total mass of the particles are measured.

[0170] d16: The diameter of particles that account for 16% of the total mass.

[0171] Ld: Calculated according to the following formula: Ld=(d84-d16) / d50

[0172] Determination of metal M content

[0173] The content of metal M can be determined using a known procedure via ICP OES (Inductively Coupled Plasma Optical Emission Spectrometry).

[0174] Ti and Zr were determined after the sample was extracted in hydrofluoric acid (e.g., leaching 0.2–0.3 g of SiO2 with 1 mL of 40% hydrofluoric acid). The clear solution was diluted in 5% nitric acid aqueous solution according to the expected Zr and Ti concentrations. The intensities measured at specific wavelengths for Zr (343.823 and 267.863 nm) and for Ti (336.122 nm) were compared with calibration curves obtained under similar analytical conditions using Zr and Ti standards (four standards at 0.10, 0.20, 1.00, and 2.00 mg / L) in the range of 0.05 to 2.00 mg / L. The amount in solids was calculated using the dilution factor and the measured dry extract of silica.

[0175] The content of Y was determined after the sample was extracted in nitric acid (e.g., 0.5 g of SiO2 was extracted with 10 mL of 85% nitric acid). After addition and mixing over a 30-minute period, the solid suspension was diluted by adding ultrapure water to 50 mL. The silica suspension in the dilute nitric acid solution was then mixed over a 30-minute period. After 30 minutes, the supernatant was filtered using a 0.45 μm PVDF syringe filter. The resulting clear solution was diluted in 5% nitric acid aqueous solution according to the expected Y concentration. The intensities measured at specific wavelengths of Y (412.831, 324.228, and 371.030 nm) were compared with calibration curves obtained under similar analytical conditions using Y standards (four standards at 0.10, 0.20, 1.00, and 2.00 mg / L) in the range of 0.05 to 2.00 mg / L. The amount in the solid was calculated using the dilution factor and the measured dry extract of silica.

[0176] Example

[0177] Example 1

[0178] 167 L of purified water and 260 g of Na₂SO₄ (solid) were introduced into a 25 L stainless steel reactor. The resulting solution was stirred and heated to 92 °C. The entire reaction was carried out at this temperature with stirring to maintain a homogeneous reaction medium. Sulfuric acid (concentration: 7.7 wt%) was introduced into the reactor to achieve a pH of 3.90.

[0179] A sodium silicate solution (SiO2 / Na2O weight ratio = 3.4; SiO2 concentration = 19.3 wt%) was introduced into the reactor at a flow rate of 111 g / min over a period of 45 s. The same sodium silicate solution was used throughout the process. Next, a sodium silicate solution and a 7.7 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 190 g / min over a period of 2 min. The flow rate of the sulfuric acid was adjusted to maintain the pH of the reaction medium at 3.95, with the sodium silicate flow rate at 111 g / min. At the end of this step, sodium silicate and a 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 111 g / min over a period of 10 min. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 3.95.

[0180] Then stop introducing acid while maintaining the addition of sodium silicate at the same flow rate until the reaction medium reaches a pH of 8.00.

[0181] Then, sodium silicate and 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 178 g / min over a 3-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0182] Simultaneously, sodium silicate (flow rate 178 g / min), titanium oxysulfate solution ([TiOSO4]: 15 wt%) (flow rate 17.3 g / min), and 96 wt% sulfuric acid solution were introduced over a 15-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0183] At the end of this process, adjust the pH of the reaction medium to 4.80 with 96 wt% sulfuric acid. Allow the reaction mixture to mature for 5 minutes. Obtain the slurry.

[0184] The reaction slurry was filtered and washed on a filter press. The resulting cake was mechanically disintegrated. The resulting slurry was dried using a nozzle spray dryer to obtain precipitated silica S1. The properties of precipitated silica S1 are reported in Table 2.

[0185] Example 2

[0186] 167 L of purified water and 260 g of Na₂SO₄ (solid) were introduced into a 25 L stainless steel reactor. The resulting solution was stirred and heated to 92 °C. The entire reaction was carried out at this temperature with stirring to maintain a homogeneous reaction medium. Sulfuric acid (concentration: 7.7 wt%) was introduced into the reactor to achieve a pH of 3.90.

[0187] A sodium silicate solution (SiO2 / Na2O weight ratio = 3.4; SiO2 concentration = 19.3 wt%) was introduced into the reactor at a flow rate of 111 g / min over a period of 45 s. The same sodium silicate solution was used throughout the process. Next, a sodium silicate solution and a 7.7 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 190 g / min over a period of 2 min. The flow rate of the sulfuric acid was adjusted to maintain the pH of the reaction medium at 3.95, with the sodium silicate flow rate at 111 g / min. At the end of this step, sodium silicate and a 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 111 g / min over a period of 10 min. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 3.95.

[0188] Then stop introducing acid while maintaining the addition of sodium silicate at the same flow rate until the reaction medium reaches a pH of 8.00.

[0189] Then, sodium silicate and 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 178 g / min over a 3-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0190] Simultaneously, over a 15-minute period, sodium silicate (flow rate 178 g / min), zirconium sulfate solution ([Zr(SO4)2,4H2O]: 23.6 wt%) (flow rate 12.3 g / min), and 96 wt% sulfuric acid solution were introduced. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0191] At the end of this process, adjust the pH of the reaction medium to 4.80 with 96 wt% sulfuric acid. Allow the reaction mixture to mature for 5 minutes. Obtain the slurry.

[0192] The reaction slurry was filtered and washed on a filter press. The resulting cake was mechanically disintegrated. The resulting slurry was dried using a nozzle spray dryer to obtain precipitated silica S2. The properties of precipitated silica S2 are reported in Table 2.

[0193] Example 3

[0194] 167 L of purified water and 260 g of Na₂SO₄ (solid) were introduced into a 25 L stainless steel reactor. The resulting solution was stirred and heated to 92 °C. The entire reaction was carried out at this temperature with stirring to maintain a homogeneous reaction medium. Sulfuric acid (concentration: 7.7 wt%) was introduced into the reactor to achieve a pH of 3.90.

[0195] A sodium silicate solution (SiO2 / Na2O weight ratio = 3.4; SiO2 concentration = 19.3 wt%) was introduced into the reactor at a flow rate of 111 g / min over a period of 45 s. The same sodium silicate solution was used throughout the process. Next, a sodium silicate solution and a 7.7 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 190 g / min over a period of 2 min. The flow rate of the sulfuric acid was adjusted to maintain the pH of the reaction medium at 3.95, with the sodium silicate flow rate at 111 g / min. At the end of this step, sodium silicate and a 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 111 g / min over a period of 10 min. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 3.95.

[0196] Then stop introducing acid while maintaining the addition of sodium silicate at the same flow rate until the reaction medium reaches a pH of 8.00.

[0197] Then, sodium silicate and 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 178 g / min over a 3-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0198] Simultaneously, over a 15-minute period, sodium silicate (flow rate 178 g / min), zirconium sulfate solution ([Zr(SO4)2,4H2O]: 23.6 wt%) (flow rate 24.7 g / min), and 96 wt% sulfuric acid solution were introduced. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0199] At the end of this process, adjust the pH of the reaction medium to 4.80 with 96 wt% sulfuric acid. Allow the reaction mixture to mature for 5 minutes. Obtain the slurry.

[0200] The reaction slurry was filtered and washed on a filter press. The resulting cake was mechanically disintegrated. The resulting slurry was dried using a spray dryer to obtain precipitated silica S3. The properties of precipitated silica S3 are reported in Table 2.

[0201] Example 4

[0202] 167 L of purified water and 260 g of Na₂SO₄ (solid) were introduced into a 25 L stainless steel reactor. The resulting solution was stirred and heated to 92 °C. The entire reaction was carried out at this temperature with stirring to maintain a homogeneous reaction medium. Sulfuric acid (concentration: 7.7 wt%) was introduced into the reactor to achieve a pH of 3.90.

[0203] A sodium silicate solution (SiO2 / Na2O weight ratio = 3.4; SiO2 concentration = 19.3 wt%) was introduced into the reactor at a flow rate of 111 g / min over a period of 45 s. The same sodium silicate solution was used throughout the process. Next, a sodium silicate solution and a 7.7 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 190 g / min over a period of 2 min. The flow rate of the sulfuric acid was adjusted to maintain the pH of the reaction medium at 3.95, with the sodium silicate flow rate at 111 g / min. At the end of this step, sodium silicate and a 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 111 g / min over a period of 10 min. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 3.95.

[0204] Then stop introducing acid while maintaining the addition of sodium silicate at the same flow rate until the reaction medium reaches a pH of 8.00.

[0205] Then, sodium silicate and 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 178 g / min over a 3-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0206] Simultaneously, over a 15-minute period, sodium silicate (flow rate 178 g / min), zirconium sulfate solution ([Zr(SO4)2,4H2O]: 23.6 wt%) (flow rate 36.6 g / min), and 96 wt% sulfuric acid solution were introduced. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0207] At the end of this process, adjust the pH of the reaction medium to 4.80 with 96 wt% sulfuric acid. Allow the reaction mixture to mature for 5 minutes. Obtain the slurry.

[0208] The reaction slurry was filtered and washed on a filter press. The resulting cake was mechanically disintegrated. The resulting slurry was dried using a nozzle spray dryer to obtain precipitated silica S4. The properties of precipitated silica S4 are reported in Table 2.

[0209] Example 5

[0210] 167 L of purified water and 260 g of Na₂SO₄ (solid) were introduced into a 25 L stainless steel reactor. The resulting solution was stirred and heated to 92 °C. The entire reaction was carried out at this temperature with stirring to maintain a homogeneous reaction medium. Sulfuric acid (concentration: 7.7 wt%) was introduced into the reactor to achieve a pH of 3.90.

[0211] A sodium silicate solution (SiO2 / Na2O weight ratio = 3.4; SiO2 concentration = 19.3 wt%) was introduced into the reactor at a flow rate of 111 g / min over a period of 45 s. The same sodium silicate solution was used throughout the process. Next, a sodium silicate solution and a 7.7 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 190 g / min over a period of 2 min. The flow rate of the sulfuric acid was adjusted to maintain the pH of the reaction medium at 3.95, with the sodium silicate flow rate at 111 g / min. At the end of this step, sodium silicate and a 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 111 g / min over a period of 10 min. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 3.95.

[0212] Then stop introducing acid while maintaining the addition of sodium silicate at the same flow rate until the reaction medium reaches a pH of 8.00.

[0213] Then, sodium silicate and 96 wt% sulfuric acid solution were introduced simultaneously at a flow rate of 178 g / min over a 3-minute period. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0214] Simultaneously, over a 15-minute period, sodium silicate (flow rate 178 g / min), yttrium sulfate solution ([Y₂(SO₄)₃,₈H₂O]: 5.52 wt% (flow rate 90.5 g / min), and 96 wt% sulfuric acid solution were introduced. The flow rate of the 96 wt% sulfuric acid solution was adjusted to maintain the pH of the reaction medium at 8.00.

[0215] At the end of this process, adjust the pH of the reaction medium to 4.80 with 96 wt% sulfuric acid. Allow the reaction mixture to mature for 5 minutes. Obtain the slurry.

[0216] The reaction slurry was filtered and washed on a filter press. The resulting cake was mechanically disintegrated. The resulting slurry was dried using a spray dryer to obtain precipitated silica S5. The properties of precipitated silica S5 are reported in Table 2.

[0217] Comparison Example 1

[0218] from The filter cake of 1165 MPa (commercially available from Solvay SA) began to reproduce Example 8 in FR2997405. The characteristics of precipitated silica CS1 are reported in Table 2.

[0219] Table 2

[0220]

[0221] Examples 6 and 7 - Comparison with Example 2

[0222] Silica-filled elastomer compositions were prepared. These compositions, expressed as parts by weight (phr) per 100 parts of elastomer, are described in Table 3.

[0223] Table 3

[0224]

[0225] The method for preparing the rubber composition is carried out in two consecutive preparation stages: a first stage of high-temperature thermomechanical processing, followed by a second stage of mechanical processing at a temperature below 110°C to introduce the vulcanization system.

[0226] The first stage was carried out using a Brabender brand internal mixer (380 mL capacity). The initial temperature and rotor speed were set to achieve a temperature drop of approximately 162°C in the mixture.

[0227] During this first stage, the elastomer and reinforcing filler (introduced in batches) are mixed with coupling agents and other additives (DPG, stearic acid, resin, ZnO, 6-PPD). This stage lasts for approximately 6 minutes.

[0228] After the mixture is cooled (to a temperature below 110°C), the vulcanization system is added during the second stage. This stage is carried out in an open mixing mill preheated to 50°C. The duration of this stage is between 2 and 6 minutes. Each final mixture is then calendered in the form of sheets with a thickness of 2-3 mm.

[0229] Mechanical properties of vulcanized products

[0230] The measurements were taken at 150°C after vulcanization.

[0231] Uniaxial tensile testing was performed on an Instron 5564 apparatus at a speed of 500 mm / min using H2 type test specimens according to the specifications of standard NF ISO 37. The modulus at x% of the stress measured at x% tensile strain is expressed in MPa.

[0232] According to standard DIN 53516, mass loss due to abrasion is measured using a Montech abrasimeter, in which a cylindrical specimen is subjected to the action of a P60 fine-grained abrasive cloth and adhered to the surface of a rotating drum under a contact pressure of 10 N over a stroke of 40 meters. The measured value is the volume of material lost after abrasion (in mm). 3 (Calculation); the smaller the value, the better the wear resistance.

[0233] Recorded the vulcanized sample (parallel hexahedral specimen: 8 mm) 2 The loss factor (tanδ) and the magnitude of the dynamic shear modulus (ΔG') were determined for the cross-section and height of the sample. The sample was subjected to alternating sinusoidal shear strain at 40 °C and 10 Hz. The strain amplitude scan was performed in an outward-return cycle, moving outward from 0.1% to 50% and then back from 50% to 0.1%. The values ​​reported in Table 4 were obtained from the return strain amplitude scan and are related to the maximum value of the loss factor (tanδmax) and the magnitude of the modulus (ΔG') between the strain values ​​of 0.1% and 50% (Paine effect).

[0234] Table 4

[0235] Example 6 Example 7 Comparison Example 2 100% Modulus (MPa) 2.1 2.3 2.1 300% modulus (MPa) 10.0 10.1 9.2 <![CDATA[Wear loss (mm 3 )]]> 125 121 130 ΔG'(MPa) 2.13 1.56 2.43 tanδmax 0.269 0.238 0.281

[0236] Compared to compositions containing precipitated silica according to the prior art, the compositions containing silica of Examples 6 and 7 of the present invention exhibit significantly reduced energy dissipation values ​​(ΔG' and tanδmax), better wear resistance, and good mechanical properties.

Claims

1. A method for preparing precipitated silica, the method comprising: (i) Provide starting solutions with a pH ranging from 2.00 to 5.

00. (ii) Simultaneously, silicates and acids are added to the starting solution to maintain the pH of the reaction medium in the range of 2.00 to 5.

00. (iii) Stop adding the acid while continuing to add the silicate to the reaction medium to raise the pH of the reaction medium to a value in the range of 7.00 to 10.

00. (iv) Simultaneously, a silicate and an acid are added to the reaction medium to maintain the pH of the reaction medium in the range of 7.00 to 10.00, wherein in step (iv), along with the addition of the acid and the salt, a compound of at least one metal M, wherein the metal M is Zr, is added to the reaction medium. (v) Stop adding the compound of the silicate and at least one metal M, while continuing to add the acid to the reaction medium to achieve a pH of less than 6.00 and obtain a suspension of precipitated silica.

2. The method according to claim 1, further comprising step (ii') between step (i) and step (ii), wherein a silicate and an acid are added to the starting solution such that the pH of the reaction medium is maintained in the range of 2.00 to 9.

50.

3. The method according to claim 1 or 2, wherein, The compound of metal M is a sulfate or oxysulfate.

4. A precipitated silica prepared by the method according to any one of claims 1 to 3, characterized in that: -From 70 to 350m 2 CTAB surface area S within the range of / g CTAB ; - At least 0.1 mol% of W M At least one metal M; as well as -The median particle size d50, measured by centrifugal sedimentation, makes (I): |d50|>183×|R ION |×|W M |-0.67×|S CTAB |+233(I) in: |d50| represents the median particle size d50 measured by centrifugation and is expressed in nm; |R ION | Represents the ionic radius of metal M, expressed in nm; |S CTAB | Represents the surface area S of the CTAB CTAB The value, in m 2 / g indicates; and |W M | Represents the molar percentage of the metal, W M The value of W M The amount of at least one element M is expressed in moles relative to the number of moles of silicon dioxide. The metal M is Zr.

5. The precipitated silica according to claim 4, wherein, The surface area S of CTAB CTAB It is in the range of 80 to 300m 2 Within the range of / g.

6. The precipitated silica according to any one of claims 4 and 5, wherein, The amount W of at least one metal M M It is in the range of 0.1 to 7.0 mol%.

7. The precipitated silica according to claim 6, wherein, The amount W of at least one metal M M It is in the range of 0.2 to 5.0 mol%.

8. A composition comprising precipitated silica according to any one of claims 4 to 7 and at least one polymer.

9. The composition according to claim 8, wherein, The at least one polymer is selected from the group consisting of elastomers.

10. An article comprising precipitated silica according to any one of claims 4 to 7 or the composition according to claim 8 or 9.

11. The article of claim 10, wherein the article is in the form of: shoe sole, floor covering, gas barrier, cable roller, seal for household appliances, seal for liquid or gas pipeline, brake system seal, pipe, sheath, cable, engine mount, battery diaphragm, or conveyor belt.

12. The article of claim 11, wherein the sheath is a cable sheath.

13. A tire or tire component comprising precipitated silica according to any one of claims 4 to 7.

14. A catalyst, catalyst carrier, or personal care or baby care product comprising precipitated silica according to any one of claims 4 to 7.

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