Silica-reinforced vulcanizable elastomer composites and vulcanized elastomer composites

Abstract

Vulcanizable elastomer composite comprising at least 40 phr silica dispersed in natural rubber, wherein, when the vulcanizable elastomer composite is vulcanized, the resulting vulcanizate has a T300 / T100 ratio of at least -0.024s + b, where s represents the amount of silica in the vulcanizable elastomer composite, expressed as parts per hundred weight rubber (phr) and b = 6.3, and the vulcanizable elastomer composite has the following additional properties: a) a tan ΔΔ60 of at most 0.0022 s - c, where c = 0.06; and b) a tensile strength in MPa of at least -0.21s + d, where d = 41; and if applicable c) Elongation at break (%) * tensile strength (MPa) of at least -211s + e, where e = 27543; and / or d) a silica content of at least 55 phr, for example at least 60 phr.

Description

[0001] The present invention relates to silica elastomer composites. In particular, the present invention relates to a silica-reinforced elastomer composite formed by a wet masterbatch process.

[0002] Numerous products of economic importance are formed from elastomeric compositions, in which particle-reinforced material is dispersed in various synthetic elastomers, natural rubber, or elastomer blends. Carbon black and silica, for example, are used as reinforcing agents in natural rubber and other elastomers. It is common to produce a masterbatch, i.e., a premix of reinforcing material, elastomer, and various optional additives, such as extender oil. Numerous products of economic importance are formed from such elastomeric compositions. These products include, for example, vehicle tires, where different elastomeric compositions can be used for the tread section, sidewalls, bead, and carcass. Other products include, for example, engine mount bushings, conveyor belts, windshield wipers, seals, linings, wheels, bumpers, and the like.

[0003] Good dispersion of particle-enhancing agents in rubber compounds has long been considered one of the most important goals for achieving good quality and consistent product performance, and considerable effort has been invested in developing methods to improve dispersion quality. Masterbatches and other mixing processes have a direct impact on mixing efficiency and dispersion quality. Generally, for example, when using carbon black to reinforce rubber, acceptable carbon black macrodispersions are often achieved in a dry-mixed masterbatch. However, achieving a high-quality, uniform dispersion of silica through dry-mixing processes is challenging, and various solutions have been offered by the industry to address this problem, such as precipitated silica in the form of "highly dispersible silica" or free-flowing "HDS" granules.More intensive mixing can improve the silica dispersion, but may also damage the elastomer in which the filler is dispersed. This is particularly problematic in the case of natural rubber, which is very susceptible to mechanical / thermal degradation.

[0004] In addition to dry mixing processes, it is known to combine elastomer latex or polymer solution and a carbon black or silica slurry in a mixing vessel. Such "wet masterbatch" techniques can be used with natural rubber latex and emulsified synthetic elastomers such as styrene-butadiene rubber (SBK). While this wet process has proven promising when using carbon black as a filler, it presents a challenge to achieve acceptable elastomer composites using silica as the filler. Specific techniques for the production of wet masterbatches, such as those disclosed in U.S. Patent No. 6,048,923, the contents of which are incorporated herein by reference, are not effective for the production of elastomer composites using silica as the sole or principal reinforcing agent.

[0005] US 2008 / 0194746 A1, US 2009 / 0111923 A1, US 2013 / 0178569 A1, WO 2011 / 083048 A1 and US 2012 / 0059121 A1 describe in their examples elastomeric composites containing at least 50 phr silica. However, these elastomeric composites exhibit insufficient properties of the vulcanizate obtained from them.

[0006] Accordingly, there is a need for elastomer composites and vulcanized elastomer composites manufactured with silica particles as the sole or main reinforcing agent and exhibiting improved mechanical properties. SUMMARY OF THE PRESENT INVENTION

[0007] A feature of the present invention is the production of elastomer composites using a liquid-based process that allows the use of silica while still achieving desirable silica-elastomer composites. A uniform distribution of silica particles within an elastomer matrix is ​​achieved by employing a continuous process using a destabilized silica slurry and an elastomer latex. The adjustment of the rates of liquid silica dispersion within the elastomer latex and the formation of a rubber network results in a unique, solid or semi-solid, silica-containing, continuous rubber phase—a coagulated mixture of silica dispersed in the elastomer latex.Dewatering the silica-containing continuous rubber phase produces a silica elastomer composite which provides improved reinforcement properties when compounded and processed into a vulcanized elastomer composite.

[0008] In the present invention, an elastomer composite is produced using a wet masterbatch process, which includes, but is not limited to, the use of a fluid comprising an elastomer latex and an additional fluid comprising a destabilized dispersion of particulate silica. The two fluids are combined under continuous flow conditions and selected flow velocities. The combination is carried out such that silica is dispersed in the elastomer latex and, in parallel (or nearly in parallel), the elastomer latex is transformed from a liquid to a solid or semi-solid elastomer composite, such as a solid or semi-solid, silica-containing, continuous rubber phase.This can occur, for example, in approximately two seconds or less, such as a fraction of a second, by one fluid impacting another with sufficient energy to achieve a uniform and intimate distribution of silica particles within the elastomer. The use of a destabilized silica dispersion in this masterbatch process enables the formation of an elastomer composite with desirable properties.

[0009] The present invention relates to vulcanizable or vulcanized elastomer composites according to claims 1 to 30, which are formed by one or more of the wet masterbatch processes described herein. Objects can be manufactured from the elastomer composite(s) of the present invention, or objects can comprise the elastomer composite(s).

[0010] It should be noted that both the preceding general description and the following detailed description are merely exemplary and explanatory, and are intended to further explain the present invention in the claimed form.

[0011] The accompanying drawings, which are considered part of the description and form a part of this application, illustrate the various features of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE IMAGES Fig. 1(a), Fig. 1(b) and Fig. 1(c) are diagrams illustrating exemplary mixing devices that can be used to produce vulcanizable elastomer composites according to embodiments of the present invention and that have been used in some of the examples. Fig.Figure 2 is a block diagram of the various steps that may occur in the formation of the vulcanizable and vulcanized elastomer composite according to embodiments of the present invention and in the production of rubber mixtures with such elastomer composites. Fig. Figure 3 is a series of diagrams that illustrate the mechanical properties of the various vulcanized silica elastomer composites in terms of silica loading (phr) ( Fig. 3A - Module ratio T300 / T100, Fig. 3B - Tensile strength (MPa), Fig. 3C - tan delta 60, and Fig. 3D - Elongation at break (%) * Tensile strength (MPa)); Stars: elastomer composites produced by dry mixing; Triangles: elastomer composites produced by batch liquid processes; Rhombuses: elastomer composites according to exemplary embodiments. Fig.Figure 4 graphically represents the modulus ratio (T300 / T100) of the samples of comparison example 1 (stars), the vulcanized elastomer composites of runs 1-4 of comparison example 8 (triangles), and the vulcanized elastomer composites of example 5 (rhombuses) with respect to the tan delta 60 values. Fig. Figure 5 graphically represents the modulus ratio (T300 / T100; diamonds) and tan delta 60 (squares) of the vulcanized elastomer composites from Example 5 in relation to the source index. Fig. Figure 6 graphically represents the modulus ratio (T300 / T100) of the vulcanized elastomer composite from the samples of Example 10 (diamonds - reference example) and Comparison Example 1 (star) with respect to the silica loading. DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0012] In one embodiment, a vulcanizable elastomer composite comprises at least 40 phr of silica dispersed in natural rubber. The silica may include precipitated silica, consist substantially of silica, or be composed of silica. When the vulcanizable elastomer composite is vulcanized, the resulting vulcanizate has a T300 / T100 ratio of at least -0.024s + b, where s represents the amount of silica in the vulcanizable elastomer composite, expressed as parts per hundred weight of rubber (phr), and b = 6.3. Furthermore, the vulcanizate of the vulcanizable elastomer composite according to the invention has the following additional properties: a) a tan Δ60 of at most 0.0022s - c, where c = 0.06; and b) a tensile strength in MPa of at least -0.21s + d, where d = 41.Optionally, the vulcanizate may also have c) an elongation at break (%) * tensile strength (MPa) of at least -211s + e, where e = 27543; and / or d) a silica content of at least 55 phr, for example, at least 60 phr. Alternatively or additionally, b may be 6.4, 6.6, or 6.8, and / or d may be 41.4. For example, T300 / T100 may have a tensile strength from -0.024s + b to 7, a tan ΔT of 60 from 0.02 to 0.0022s - c, a tensile strength of -0.21s + d to 35 or 40, and / or an elongation at break (%) * tensile strength (MPa) of -211s + e to 21500.

[0013] Alternatively or additionally, a vulcanizable elastomer composite comprises at least 40 or, for example, 55 phr of silica dispersed in natural rubber. The silica may include precipitated silica, consist substantially of silica, or be composed of silica. When the vulcanizable elastomer composite is vulcanized, the resulting vulcanizate has a T300 / T100 ratio of at least 5.5, a tan Δ60 of at most 0.05, and a swelling index of 1.80 to 2.20. In another embodiment, a vulcanizable elastomer composite comprises at least 40, for example, at least 50 phr of silica dispersed in natural rubber. When the vulcanizable elastomer composite is vulcanized, it has a T300 / T100 ratio of at least -0.025s + 6.2, for example at least -0.025s + 6.3 or 6.4, and a swelling index of 1.80 to 2.20.The vulcanizable elastomer composite may comprise a dehydrated wet masterbatch of silica dispersed as a slurry in field latex, which may be stabilized, e.g. with ammonia, de-sludged, or chemically or enzymatically modified.

[0014] In a preferred process for producing a vulcanizable elastomer composite, silica is selectively and strategically introduced into an elastomer latex in a continuous, rapid wet masterbatch process. This process can be carried out in a semi-constrained reaction zone, such as a tubular mixing chamber or other mixing chamber of an apparatus suitable for carrying out such a process under controlled flow and velocity parameters, and which leads to advantageous properties solely for this selective and strategic use of the silica. As explained in more detail herein, "selective" refers to the use of a destabilized silica dispersion in the present invention.With regard to "strategic" introduction, the present invention uses at least two separate fluids: one fluid comprising an elastomer latex and another fluid containing the destabilized silica dispersion. The two fluids can be pumped or transferred into a reaction zone, such as a semi-constrained reaction zone. The two fluids can be combined under continuous flow conditions, as well as under selected volumetric flow and velocity conditions. Combining under pressure with selected differential velocity conditions has sufficient energetic impact to distribute silica within the elastomer latex within two seconds or less, such as milliseconds, and the elastomer latex transitions from a liquid to a solid phase, such as a silica-elastomer composite in the form of a solid or semi-solid, silica-containing, continuous rubber phase.

[0015] The preferred method for producing a vulcanizable silica elastomer composite may comprise, essentially consist of, be composed of, or include: (a) Providing a pressurized continuous flow of at least a first fluid comprising a destabilized silica dispersion and a continuous flow of a second fluid comprising elastomer latex; (b) Adjusting the flow rates of the first fluid and the second fluid to obtain a silica content of about 15 phr to about 180 phr in the silica elastomer composite; and c) Combining the first and second fluid streams (for example, in a confined reaction zone) with sufficient energy to distribute the silica within the elastomer latex, to provide a flow of a solid, silica-containing, continuous rubber phase or a semi-solid, silica-containing, continuous rubber phase. The process converts the liquid elastomer latex into a stream of a solid or semi-solid, silica-containing, continuous rubber phase. The silica-containing, continuous rubber phase can be obtained as a substantially continuous flow of the solid or semi-solid, silica-containing, continuous rubber phase.

[0016] An additional improvement in mechanical properties is associated with the use of latex concentrate, the destabilization of the silica slurry using salt, with or without additional acid, and a swelling index in the vulcanized elastomer composite of about 1.80 to about 2.20, for example from about 1.90 to about 2.10, or from about 1.95 to about 2.05.

[0017] Further details and / or options for the production of vulcanizable elastomer composite are described below.

[0018] “Silica,” as used herein, refers to particulate silicon dioxide, or particles coated with silicon dioxide, and includes precipitated silica in any form, such as highly dispersible (HDS) granules, non-HDS granules, silica aggregates and silica particles; colloidal silica; pyrogenic silicon dioxide; and any combination thereof. Such silicon dioxide particles or silica-coated particles may be chemically modified to exhibit functional groups on the silica surface in bound (e.g., chemically bonded) or adsorbed (e.g., adsorbed) form. Thus, “silica” includes any particles having a surface consisting substantially of silica or of silica having bound or adsorbed functional groups.

[0019] “Dispersion”, as used here, refers to a stable suspension of solid particles in an aqueous liquid, wherein the surface charge of the particles prevents particle agglomeration and the dispersion is characterized by a zeta potential magnitude of greater than or equal to 30 mV.

[0020] The zeta potential is used to measure the stability of charged particles, such as silica particles, dispersed in a fluid. Zeta potential measurements can have a deviation, for example of about ±2 mV, and the magnitude of the zeta potential, as used here, refers to the absolute value of the number; that is, for example, a zeta potential value of -30 mV has a greater magnitude than a zeta potential value of -10 mV.

[0021] “Destabilized dispersion,” as used here, denotes a suspension of solid particles in an aqueous liquid, wherein the surface charge of the particles has been reduced by the presence of an agent or by treatment of the solid particle, and is characterized by a zeta potential magnitude of less than 30 mV, or more preferably a zeta potential of less than 28 mV or less than 25 mV. The aqueous liquid can be water, a water-miscible liquid (for example, alcohol or ether), a partially water-miscible liquid, or a mixture of fluids containing at least one water-miscible or partially water-miscible liquid.

[0022] The terms "silica slurry" and "dispersion," as used here, refer to a dispersion of silica in an aqueous liquid, where the surface charge of the particles prevents particle agglomeration and the dispersion is characterized by a zeta potential magnitude of greater than or equal to 30 mV. A silica slurry or dispersion can be destabilized by adding sufficient agents or by treating the silica to reduce its surface charge, and the resulting destabilized silica slurry (or destabilized silica dispersion) is characterized by a zeta potential magnitude of less than 30 mV.

[0023] The terms "uniform" and "consistent" used here mean, as is customary for those skilled in the art, that the concentration of a component, for example, a particulate filler, in a specific fraction or percentage (for example, 5%) of a volume is the same (e.g., within 2%) as the concentration of that component in the total volume of the material in question, such as an elastomeric composite or a dispersion. Those skilled in the art will be able to verify the statistical uniformity of the material, if necessary by measuring the concentration of the component using several samples from different locations (for example, near the surface or deeper in the bulk).

[0024] “Silica elastomer composite,” as used here, means a masterbatch (a premix of reinforcing material, elastomer, and various optional additives, such as extender oil) of coherent rubber, which includes a reinforcing fraction (e.g., approximately 15 phr to approximately 180 phr) of dispersed silica. The silica elastomer composite may optionally contain other components, such as acid, salt, antioxidant, anti-degradation agent, coupling agent, small amounts (e.g., 10 wt% or less based on the total particle weight) of other particles, processing aids, and / or extender oil, or any combination thereof.

[0025] The “solid, silica-containing, continuous rubber phase,” as used here, refers to a composite with a continuous rubber phase and a uniformly dispersed silica phase, as well as, for example, up to 90 wt.% aqueous liquid. The solid, silica-containing, continuous rubber phase may be in the form of a continuous rope or coil. Upon compression, these items release water. The solid, silica-containing, continuous rubber phase may optionally contain other components, such as acid, salt, antioxidants, coupling agents, small amounts of other particles (e.g., 10 wt.% or less based on the total particle count), and / or processing oil, or any combination thereof.

[0026] The term "semi-solid, silica-containing, continuous rubber phase," as used here, describes a composite with a paste-like consistency that incorporates a silica-containing, continuous rubber phase. The semi-solid product has a continuous rubber phase in which the encapsulated silica is uniformly distributed. Upon further processing in one or more subsequent steps, selected to transform the paste-like or gel-like material into a solid, silica-containing, continuous rubber phase, the semi-solid, silica-containing, continuous rubber phase remains coherent and expels water while maintaining a constant solids content.

[0027] The term “coherent” material, as used here, denotes a material which exists in an essentially uniform form, which is formed by the adhesion of many small parts together, such as an elastic, solid rubber mass formed by the adhesion of many small rubber particles together.

[0028] A "continuous flow," as used here, is a steady or constant flow of a fluid without interruption from a supply source (e.g., a tank). However, it should be understood that a temporarily interrupted flow (e.g., for one second or a few minutes) is still considered a continuous flow (for example, when switching supplies from different supply areas, such as containers and the like, or when interrupting flows to adjust subsequent processes or perform equipment maintenance).

[0029] In a preferred embodiment, vulcanizable elastomer composite can be produced in a continuous flow process using a liquid mixture of the elastomer latex and a destabilized silica dispersion. Any device, apparatus, or system can be used, provided that the device, apparatus, or system can be operated to combine a liquid mixture of elastomer latex and a destabilized silica dispersion under continuous flow conditions and under controlled volumetric flow, pressure, and velocity conditions, including, but not limited to, those described in Fig.1(a), (b), or (c), the device shown, or any type of eductor or ejector, or any other device that enables a continuous flow of at least two fluid streams under controlled volumetric flow, pressure, and velocity conditions into and through a reaction zone. The device described in US 2011-0021664, US 6,048,923, WO 2011 / 034589, WO 2011 / 034587, US 2014-0316058, and WO 2014 / 110499 (each incorporated in its entirety by reference) may be used or adapted for the present processes. Ejectors and eductors or siphons such as water jet eductors or steam jet siphons may also be used (e.g., the commercially available products of Schutte & Koerting, Trevose, PA).

[0030] The device may include various supply containers, pipes, valves, measuring instruments, and pumps for controlling the volumetric flow rate, pressure, and velocity. Furthermore, various types and sizes of nozzles or other orifice size control elements (3a) may be used to control the velocity of the silica slurry, as at the inlet (3) into the Fig. 1 (a), (b) and (c) are indicated. The volume of the reaction zone (13) can be selected appropriately to provide the desired volumetric flow rates of the liquids and the elastomer composite. The inlet (11) for introducing the elastomer latex into the reaction zone can be conical to provide different volumetric flow rates and velocities. The devices can include an inlet (11) with a uniform diameter, without a taper at the opening leading to the reaction zone.

[0031] In this process, a fluid containing an elastomeric latex and an additional fluid containing a destabilized dispersion of silica, for example as a pressurized jet, are combined under continuous flow conditions and selected volumetric flow rates, pressure ratios, and velocities to rapidly and thoroughly mix the two fluids. This combination, for example in a semi-constrained space under pressure, occurs such that silica is distributed throughout the entire elastomeric latex, and the elastomeric latex simultaneously transitions from a liquid to a solid or semi-solid phase. This involves a liquid-to-solid transition or coagulation of the latex, whereby the silica and water are trapped within the rubber, and a solid or semi-solid, silica-containing, continuous rubber phase exits the reaction zone in a continuous or semi-continuous flow (e.g.,...).from the opening at the bottom (7) into the . Fig. 1 (a) - (c)). At this point, the product can be considered an elastomeric composite of a continuous rubber phase containing silica particles, a silica-containing coherent rubber, or a silica-elastomer composite. It is assumed that the silica particles must first be dispersed in the elastomeric latex to obtain the desired product, and the inversion from the liquid to the solid phase follows immediately after the silica distribution. This is due to the continuous and extremely rapid rate of fluid mixing (i.e., less than 2 seconds, less than 1 second, less than 0.5 seconds, less than 0.25 seconds, less than 0.1 seconds, or on the order of milliseconds), and the energetic and intimate mixing of relatively small volumes of fluids in the reaction zone (for example, fluid volumes on the order of 10 to 500 cm³). 3The parallel steps of silica particle distribution and the transformation from the liquid to the solid phase of the elastomer latex can occur almost simultaneously. The "reaction zone," as used here, is the zone where intimate mixing occurs in conjunction with coagulation of the mixture. The mixture moves through the reaction zone and to an outlet (7).

[0032] An exemplary process for producing the vulcanizable elastomer composite involves the simultaneous injection of a first fluid containing a destabilized silica dispersion and a second fluid containing an elastomer latex (e.g., natural rubber latex) into a reaction zone. The first fluid, containing the destabilized silica dispersion, can be injected at a flow rate relative to its volume, and the second fluid, containing the elastomer latex, can be injected at a flow rate relative to its volume (i.e., volumetric flow rates). The volumetric flow rates of either the first fluid, the second fluid, or both can be controlled or adjusted to produce an elastomer composite with a silica content of 15 to 180 parts per hundred parts by weight of rubber (phr) (e.g., 15 to 180 parts per hundred parts by weight of rubber).(from 35 to 180 phr, from 20 phr to 150 phr, from 25 phr to 125 phr, from 25 phr to 100 phr, 35 to 115 phr, or from 40 phr to 115 phr, or from 40 phr to 90 phr, and the like). The fluid containing the destabilized silica dispersion may, in some embodiments, be referred to here as the first fluid. With regard to the fluid containing the elastomer latex, this fluid is to be considered a separate fluid. Both fluids may be introduced via one or more inlets or injection points.

[0033] The volumetric flow rate ratio of the first fluid (destabilized silica dispersion) to the second fluid (latex fluid) can be adjusted to enable the formation of the desired elastomer composite. Examples of such volumetric flow rate ratios include, but are not limited to, ratios from 0.4:1 (first fluid to second fluid) to 3.2:1; from 0.2:1 to 2:1, and so on. The volumetric flow rate ratio between the first and second fluids can be adjusted by any means or techniques. For example, the volumetric flow rate of the first or second fluid, or of both fluids, can be adjusted by: a) increasing the volumetric flow rate, b) decreasing the volumetric flow rate, and / or c) adjusting the flow rates of the fluids relative to each other.The pressure exerted on the flow of the first fluid by applying physical constraints causes the formation of a high-velocity jet, enabling the rapid combination of the destabilized silica dispersion with the elastomer latex, for example, within a fraction of a second. For instance, the time during which the two fluids mix and liquid-solid phase inversion occurs can be on the order of milliseconds (e.g., approximately 50 ms to approximately 1500 ms or approximately 100 ms to approximately 1000 ms). If the velocity of the first fluid, for a given selection of fluids, is too slow to mix the fluids adequately, or if the residence time is too short, a solid rubber phase and a solid product flow cannot develop. If the process duration is too long, back pressure can build up in the reaction zone and terminate the continuous material flow.If the speed of the first fluid is too fast and the duration of the process is too short, a solid rubber phase and a solid product flow cannot develop.

[0034] As described above, the relative volumetric flow rates of the first fluid (destabilized silica slurry) and the second fluid (latex) can be adjusted, and if at least one salt is used as a destabilizing agent, it is preferred to adjust the volumetric flow rate ratio of destabilized particle slurry to elastomer latex to between 0.4:1 and 3.2:1. Other volumetric flow rate ratios can also be used.

[0035] If at least one acid is used as a destabilizing agent, it is preferred to adjust the volumetric flow rate ratio of destabilized silica slurry to elastomer latex to 0.2 : 1 to 2 : 1. Other volumetric flow rate ratios may also be used.

[0036] The elastomer latex may contain at least one base (such as ammonia), and the destabilized silica dispersion (or destabilized particle dispersion) may be achieved by adding at least one acid, wherein the molar ratio of the acid in the first fluid (silica) and the base (e.g., ammonia) in the second fluid (latex) is at least 1.0, or at least 1.1, or at least 1.2, such as from 1 to 2, or 1.5 to 4.5. The base may be present in the elastomer latex in a variety of concentrations, such as, but not limited to, 0.3 wt% to about 0.7 wt% (based on the total weight of the elastomer latex) or other amounts below or above this range.

[0037] The destabilized particle dispersion can be injected into the reaction zone as a continuous jet of fluid at high velocity, for example, at approximately 6 m / s to approximately 250 m / s, or approximately 30 m / s to approximately 200 m / s, or approximately 10 m / s to approximately 150 m / s, or approximately 6 m / s to approximately 200 m / s. The elastomer latex-containing fluid can be introduced at a comparatively lower velocity, for example, at approximately 0.4 m / s to approximately 11 m / s, or approximately 0.4 m / s to approximately 5 m / s, or approximately 1.9 m / s to approximately 11 m / s, or approximately 1 m / s to approximately 10 m / s, or approximately 1 m / s to approximately 5 m / s. The fluid velocities are selected to ensure optimal mixing of the fluids and rapid coagulation of the elastomer latex.The velocity of the elastomer latex fed into the reaction zone should preferably be high enough to generate turbulent flow and thus achieve better mixing with the destabilized particle slurry. However, the velocity of the elastomer latex should be kept low enough to prevent coagulation of the latex by shear forces before mixing with the destabilized particle slurry. Additionally, the velocity of the elastomer latex before entering the reaction zone should be kept low enough to prevent clogging of the latex supply lines by shear-induced coagulation. Similarly, there is also an optimized range for the velocity of the destabilized particle dispersion.It is theoretically assumed that if the velocity of the destabilized particle slurry is too high, the velocity of the agglomeration of silica particles induced by the shear forces may be too high to allow sufficient, uniform mixing between silica particles and elastomer latex particles.

[0038] Shear thickening through agglomeration and cross-linking of silica particles could also reduce the turbulence of the destabilized silica slurry and negatively affect the mixing between silica and latex. Conversely, sufficient mixing between silica and elastomer latex particles cannot occur if the velocity of the destabilized silica slurry is too low. Preferably, at least one of the fluids entering the reaction zone exhibits turbulent flow. In general, due to the much higher viscosity of a typical destabilized silica dispersion compared to a typical elastomer latex, a much higher velocity of the destabilized silica dispersion is required to generate good fluid dynamics for mixing with the elastomer latex and rapid coagulation of the latex.Such a high-velocity flow of the destabilized silica dispersion can induce cavitation in the reaction zone to improve rapid mixing of the fluids and distribution of the silica particles in the elastomer latex. The velocity of the destabilized silica dispersion can be changed by using different volumetric flow rates or by using a different nozzle or tip (wider or narrower in diameter) at the inlet (3a) that feeds in the initial fluid containing the destabilized silica dispersion.When using a nozzle to increase the velocity of the destabilized silica dispersion, it can be supplied at a pressure of approximately 30 psi to approximately 3000 psi, or approximately 30 psi to approximately 200 psi, or approximately 200 psi to approximately 3000 psi, or approximately 500 psi to approximately 2000 psi, or at a relative pressure at least twice as high, or two to 100 times higher, than the pressure exerted on the fluid containing the elastomer latex. The second fluid containing the elastomer latex can, for example, be supplied at a pressure in the range of approximately 20 psi to approximately 30 psi. The pressure in the first fluid supply system can be up to approximately 500 psi (1 psi = 6.895 kPa).

[0039] Based on the production variables described here, such as the velocity of the fluid from the destabilized particle slurry, the velocity of the latex fluid, the relative flow velocities of the fluid from the destabilized particle slurry and the latex fluid, the concentration of the destabilizing agent (e.g., a salt and / or an acid), the silica concentration in the destabilized slurry, the rubber weight percent in the latex, the ammonia concentration in the latex, and / or the acid-to-ammonia ratio (if present), it is possible to control, maintain, and / or predict the formation of a solid or semi-solid silica-containing continuous rubber phase over a range of desired silica contents. Thus, the process can be operated over an optimized range of variables.Thus, a) the velocity of one or both fluids, b) the volumetric flow ratio of the fluids, c) the destabilized state of the silica, d) the concentration of particulate silica in the destabilized silica dispersion, for example, 6 to 35 wt.%, and e) the dry rubber content of the latex, for example, 10 to 70 wt.%, can permit mixing under high energetic impact to cause inversion of the elastomer latex from the liquid to the solid phase and to disperse the silica uniformly in the latex at a selected silica:rubber ratio, thereby forming a flow of a solid or semi-solid, silica-containing, continuous rubber phase. Recovery of the flow of a solid or semi-solid, silica-containing, continuous rubber phase can be achieved using any conventional solid or semi-solid material flow recovery technique.Recovery may involve introducing the solid or semi-solid stream into a container, tank, or other holding device. Such containers or holding vessels may contain a solution of salt or acid, or both, to further coagulate the product toward a more elastic state. Recovery may, for example, involve transporting or pumping the solid stream to other processing areas or devices, some of which are described here. Recovery may be carried out continuously, semi-continuously, or in a batch process. The outflow side of the reaction zone is preferably semi-constrained and open to the atmosphere, and the stream of solid or semi-solid elastomer composite is preferably recovered at ambient pressure to allow continuous operation of the process.

[0040] The flow of a solid, silica-containing, continuous rubber phase can take the form of more or less elastic, rope-like "worms" or spheres. In one embodiment, the solid, silica-containing, continuous rubber phase has an elongation at break of, or is an article having an elongation at break of at least about 100%, for example, about 100% to about 600%, about 120% to about 200%, about 130% to about 150%, about 130% to about 250%, about 150% to about 200%, about 200% to about 300%, about 300% to about 600%, about 300% to about 500%, or about 300% to about 400%. In other cases, a semi-solid, silica-containing, continuous rubber phase may be present in the form of a non-elastic, viscous paste or a gel-like material that can develop elastic properties. In any case, the product is a coherent, flowing solid whose consistency may be highly elastic or slightly elastic and viscous.The material exiting the reaction zone can be a substantially constant flow, synchronized with the ongoing feed of elastomer latex and the destabilized dispersion of silica fluids into the reaction zone. Process steps, such as fluid production, can be carried out continuously, semi-continuously, or in batches. The resulting solid or semi-solid, silica-containing, continuous rubber phase can subsequently undergo further processing, including continuous, semi-continuous, or batch processes.

[0041] The solid or semi-solid, silica-containing, continuous rubber phase produced by the process contains water or another aqueous liquid, and the dissolved substances of the original fluids, and contains, for example, approximately 40 wt.% to approximately 95 wt.% water, or 40 wt.% to approximately 90 wt.% water, or approximately 45 wt.% to approximately 90 wt.% water, or approximately 50 wt.% to approximately 85 wt.% water, or approximately 60 wt.% to approximately 80 wt.% water, based on the total weight of the flow from the silica-elastomer composite. Optionally, after formation of the solid or semi-solid, silica-containing rubber phase with such water contents, the product can be subjected to suitable dehydration and mastication steps, as well as compounding steps, to develop desired rubber properties and to produce rubber compounds.Further details of the process and other post-processing steps are given below and can be used in any embodiment of the present invention.

[0042] A semi-solid, silica-containing, continuous rubber phase can be converted into a solid, silica-containing, continuous rubber phase. This can be achieved, for example, by subjecting the semi-solid, silica-containing, continuous rubber phase to mechanical processing steps that remove water from the composite and / or by allowing the semi-solid material to stand for a period of time (e.g.,after recovery from the reaction zone in an offline location), for example, for 10 minutes to 24 hours or more, and / or by heating the semi-solid, silica-containing, continuous rubber phase to reduce its water content (for example, at a temperature of about 50 °C to about 200 °C); and / or by treating the semi-solid material with acid or additional acid, such as in an acid bath, or with salt or additional salt, or in a salt bath, or with a combination of acid and salt, and the like. One or more of these steps, or all of them, may be used. In fact, one or more, or all of the step(s) may be used as a further processing step, even if a solid, silica-containing, continuous rubber phase is recovered initially or subsequently.The elongation at break of the resulting solid, silica-containing, continuous rubber phase or of the objects comprising the solid, silica-containing, continuous rubber phase may be at least about 100%, for example about 100% to about 600%, about 130% to about 150%, about 120% to about 200%, about 200% to about 500%, about 300% to about 400%, about 150% to about 200%, or about 130% to about 250%.

[0043] The degree of destabilization of the silica slurry determines, at least in part, the amount of silica that can be present in the silica-elastomer composite for a given silica concentration in the slurry and a given dry rubber content of the latex (e.g., trapped and evenly distributed within the composite). At lower selected target ratios of silica to rubber (e.g., 15 phr to 45 phr), the concentration of destabilizing agents in the silica slurry may not be high enough to ultimately cause rapid coagulation of the silica / latex mixture and the formation of a solid or semi-solid, continuous rubber phase containing silica. Additionally, the selection of appropriate silica and rubber concentrations and suitable relative fluid flow rates represents a further consideration for the formation of the solid or semi-solid product.For example, at relatively low volumetric flow rates of destabilized slurry to latex, the amount of destabilizing agent in the destabilized silica slurry may be insufficient to allow rapid coagulation of the elastomer latex in the reaction zone. Generally, for a given elastomer latex, lower silica loadings can be achieved by increasing the destabilization of the silica slurry and / or by reducing the weight percentage of silica in the destabilized slurry.

[0044] When a silica dispersion is destabilized, the silica particles tend to flocculate. If a silica dispersion is destabilized too much, the silica can precipitate out of the solution and no longer be suitable for use in preferred embodiments.

[0045] When destabilization occurs, the surface charges on the silica particles are typically not completely removed. However, sometimes, when the silica particles or the silica dispersion are treated for destabilization, the isoelectric point (IEP) may be exceeded, shifting from a negative to a positive zeta potential. Generally, for silica, during destabilization, the net charge on the surface of the silica particles is reduced, and the magnitude of the zeta potential decreases.

[0046] For higher silica:rubber ratios in the silica-elastomer composite, higher silica concentrations can be selected in the destabilized slurry and / or a higher silica fluid:latex fluid flow rate ratio. Once the silica slurry is destabilized and initially combined with the latex fluid, and provided the mixture does not coagulate, the flow rate ratio of the first fluid and the second fluid can be adjusted, for example, by reducing the latex flow rate, effectively resulting in a higher silica:rubber ratio in the elastomer composite. During this step of adjusting the amount of latex, the quantity is, or will be, adjusted to a level that does not excessively dilute the concentration of the destabilizing agent in the overall mixture, allowing the desired product to form within the residence time in the reaction zone.Several options are available to achieve a desired silica-to-rubber ratio in the elastomer composite. Optionally, the degree of destabilization of the silica slurry can be increased, for example, by reducing the magnitude of the zeta potential of the destabilized silica slurry (e.g., by adding more salt and / or acid). Alternatively, the silica concentration in the destabilized silica slurry can be adjusted, for example, by increasing or decreasing it. Another option is to use a latex with a higher rubber content, dilute the latex to a lower rubber content, or increase the relative flow rate of the latex.As a further option, the flow rate and the opening size (both of which can control or influence the velocity of the fluid(s)) or the relative orientation of the two fluid flows can be modified to shorten or lengthen the residence time of the combined fluids in the reaction zone; and / or the extent and type of turbulence at the point of contact between the first and second fluids can be changed. Any one, two, or more of these options can be used to adjust the process parameters and obtain a predetermined or desired silica:rubber ratio in the elastomer composite.

[0047] The extent or degree of destabilization of the silica slurry is an important factor in determining the silica:rubber ratios that can be achieved in the silica-elastomer composite. A destabilizing agent used to destabilize the silica in the slurry can accelerate the coagulation of the elastomer latex particles when the destabilized silica slurry is mixed with the elastomer latex in the reaction zone. It is hypothesized that the rate of latex coagulation in the reaction zone may depend on the concentration of the destabilizing agent in the combined fluids.It has been observed that a threshold concentration of a destabilizing agent in the mixture of combined fluids can be determined at the time of mixing. This threshold concentration is effective for producing a solid or semi-solid silica-containing continuous rubber phase when the silica-elastomer composite production process is operated under various conditions. An example of selecting and adjusting process conditions to achieve the threshold concentration and obtain a solid or semi-solid silica-containing continuous rubber phase is described in the examples below. If the threshold concentration is not reached or is exceeded for a given selection and composition of fluids, flow rates, and velocities, a solid or semi-solid silica-containing continuous rubber phase is generally not produced.

[0048] The minimum amount of destabilization of the silica slurry (or particle slurry) is achieved by a zeta potential magnitude of less than 30 mV (for example, with zeta potentials such as -29.9 mV to approximately 29.9 mV, approximately -28 mV to approximately 20 mV, approximately -27 mV to approximately 10 mV, approximately -27 mV to approximately 0 mV, -25 mV to approximately 0 mV, -20 mV to approximately 0 mV, -15 mV to approximately 0 mV, approximately -10 mV to approximately 0 mV, and the like). If the particle slurry has been destabilized within this zeta potential range, then the silica in the destabilized slurry can be incorporated into a solid or semi-solid, silica-containing, continuous rubber phase when combined with the elastomer latex.

[0049] While it may be desirable to destabilize the latex under shear conditions, such as those present when the latex is continuously pumped into the reaction zone, before combining it with the silica-containing slurry, it is difficult to destabilize the latex fluid beforehand without causing premature coagulation of the latex. However, the destabilizing agent used in the destabilized silica slurry can be present in excess to enhance latex destabilization and / or mitigate the dilution of the agent once the destabilized silica slurry and latex fluid are combined. As another option, particularly at high silica concentrations (e.g., > 25 wt% silica in the silica slurry), some added destabilizing agent can be added separately to the mixture of the destabilized silica slurry and elastomer latex in the reaction zone to enhance latex coagulation.

[0050] Without being bound to a specific theory, it is assumed that the manufacturing process for the silica-elastomer composite, when the two fluids are combined and phase inversion occurs, forms interpenetrated coherent networks of rubber particles and silica aggregates within approximately two seconds or less, such as a fraction of a second. This results in a solid or semi-solid material containing these networks with trapped water. Such rapid network formation enables the continuous production of a solid or semi-solid, silica-containing, continuous rubber phase.It is theoretically assumed that shear-induced agglomeration of silica particles during the passage of the destabilized silica slurry through the inlet nozzle is beneficial for bonding with the elastomer latex, creating a unique, uniform particle arrangement in rubber masterbatches and enclosing the silica particles in the rubber through heterocoagulation between silica and rubber particles. It is further theoretically assumed that without such an interpenetrating network, no composite can be formed from a solid or semi-solid continuous rubber phase containing dispersed silica particles in the form of a spiral or solid pieces, which, for example, encloses 40–95 wt% water, and retains all or most of the silica during subsequent dewatering processes, including extrusion and high-energy mechanical processing.

[0051] It is theoretically assumed that the formation of a silica network is at least partially caused by the shear-induced agglomeration of the silica particles, while the destabilized silica slurry is guided at high velocity through a pressure nozzle (3a) via the first inlet (3) into the reaction zone (13), as shown in Fig. Figure 1 illustrates this process. This process is facilitated by the reduction in the stability of the silica in the destabilized slurry if the silica slurry has been destabilized (e.g., by treating the silica slurry with salt or acid or both).

[0052] It is theoretically assumed that the inversion of latex from the liquid to the solid phase can result from various factors, including shear-induced coagulation from mixing with the high-velocity jet of the destabilized silica slurry, the interaction of the silica surface with the latex components, ionic or chemical coagulation from contact with the destabilizing silica slurry, and a combination of these factors. To form the composite material, which comprises the interpenetrated silica and rubber networks, both the rates of any network formation and the mixing rate should be coordinated. For example, agglomeration and network formation under shear conditions proceed rapidly when using highly destabilized silica slurries with high salt concentrations in the slurry.In this case, the flow rates and velocities are adjusted so that the latex has a high coagulation rate for the formation of the interpenetrated silica / rubber network. With slightly destabilized silica slurries, the formation rates are slower.

[0053] An exemplary process for the production of a silica-elastomer composite involves feeding a continuous fluid stream, which contains at least elastomer latex (sometimes referred to as the second fluid), through the inlet 11 ( Fig. 1 (a), (b), and / or (c)) into a reaction zone 13 at a volumetric flow rate of about 20 l / h to about 1900 l / h. The process further comprises the injection of a continuous stream of another fluid, comprising a destabilized particle dispersion, through inlet 3 (sometimes referred to as the first fluid) under pressure, which can be achieved by nozzle tips (in Fig.1, at 3a), with a volumetric flow rate of 30 l / h to 1700 l / h. The destabilized state of the particle dispersion and the collision of the two fluid streams (introduced at inlets 3 and 11) under high-energy conditions, which arise from the first fluid being introduced as a high-speed jet (e.g., about 6 m / s to about 250 m / s) and striking the slower (e.g., 0.4 to 11 m / s) latex stream at the entrance to the reaction zone at an approximately perpendicular angle to the flow direction of the high-speed jet of the first fluid, effectively cause the intimate mixing of the silica with the latex stream, thereby promoting a uniform distribution of particles in the stream of solid, silica-containing, continuous rubber phase from the outlet of the reaction zone.

[0054] Optionally, the elastomer latex introduced through inlet 11 can be, for example, a mixture of two or more latizes, such as a mixture of two or more synthetic latizes. Optionally, the devices in Figures (a), (b) and / or (c) can be modified to have one or more additional inlets for introducing other components into the reaction zone, such as one or more additional latizes. For example, in Fig.1(c) In addition to the use of inlet 11, inlet 14 may be used to introduce further latex. The one or more additional inlets may be sequential to each other, or in any orientation to each other or adjacent to each other, as long as the material introduced through the inlet(s) (e.g., latex) has sufficient time to disperse or be incorporated into the resulting flow. In WO 2011 / 034587, which is incorporated herein in its entirety by reference, Fig. 1, Fig. 2A and Fig.2B Examples of additional inlets and their orientations that can be adapted for the production of vulcanizable elastomer composites according to embodiments of the present invention. In a particular example, one inlet can introduce a stream containing natural rubber latex, and an additional inlet can introduce a synthetic elastomeric rubber, and these latex streams are combined with the stream of destabilized silica dispersion to form a stream of a solid or semi-solid silica-containing continuous rubber phase. If more than one inlet is used for introducing the elastomeric latex, the flow velocities can be the same or different from one another.

[0055] Fig. Figure 2 presents an example, in which a block diagram illustrates the various steps that can occur during the formation of the elastomer composite. As shown in Fig.As shown in Figure 2, the destabilized dispersion of silica-containing particles (first fluid) 100 is introduced into the reaction zone 103, and the fluid containing the elastomer latex (second fluid) 105 is also fed into the reaction zone. Optionally, a flow of the solid or semi-solid, silica-containing, continuous rubber phase can exit the reaction zone 103 and optionally be introduced into a collection zone 116 (e.g.,a collection tank, with or without the addition of a salt or acid solution to improve rubber coagulation and silica / rubber network formation); and can optionally be introduced directly or, after branching off to a holding zone 116, into a dewatering zone 105; optionally into a continuous mixer / compounder 107; optionally into a mill 109 (for example, an open mill, also known as a roller mill); be subjected to additional grinding operations 111 (under the same or different conditions as mill 109) (such as the same or different energy input); be subjected to optional mixing by the mixer 115; and / or be granulated using a granulator 117, and subsequently optionally formed into bales using a baler 119, and optionally broken up using an additional mixer 121.

[0056] With regard to the silica, one or more types of silica or any combination of silicas can be used in each embodiment of the present invention. Suitable silicas for reinforcing elastomer composites can be selected by means of a BET surface area of ​​approximately 20 m². 2 / g up to about 450 m 2 / g; approximately 30 m 2 / g up to about 450 m 2 / g; approximately 30 m 2 / g up to about 400 m 2 / g; or about 60 m 2 / g up to about 250 m 2 / g characterized; and for heavy-duty vehicle tire treads, a preferred BET surface area of ​​approximately 60 m² applies. 2 / g up to about 250 m 2 / g or for example from about 80 m 2 / g up to about 200 m 2 / g. Highly dispersible precipitated silica can be used as a filler in the present process. Highly dispersible precipitated silica (“HDS”) refers to silica that exhibits a pronounced ability to deagglomerate and disperse within an elastomeric matrix. Such determinations can be made in known manner by electron or light microscopy of thin sections of elastomeric composites. Examples of commercially available grades of HDS include Perkasil® GT 3000GRAN Silica from WR Grace & Co., Ultrasil® 7000 Silica from Evonik Industries, Zeosil® 1165 MP and 1115 MP Silica from Solvay SA, Hi-Sil® EZ 160G Silica from PPG Industries, Inc., and Zeopol® 8741 or 8745 Silica from JM Huber Corporation. Conventional, non-HDS precipitated silica can also be used. Examples of commercial grades of conventionally precipitated silica include Perkasil® KS 408 Silica from WR Grace & Co, and Zeosil® 175GR Silica from Solvay SA.Examples of suitable silicas include Ultrasil® VN3 Silica from Evonik Industries, Hi-Sil® 243 Silica from PPG Industries, Inc., and Hubersil® 161 Silica from JM Huber Corporation. Hydrophobic, precipitated silicas surface-modified with silane coupling reagents can also be used. Examples of commercially available hydrophobic, precipitated silicas include Agilon® 400, 454, 458 Silica from PPG Industries, Inc., and Coupsil Silica from Evonik Industries, such as Coupsil 6109 Silica.

[0057] Typically, the silica (e.g., silica particles) have a silica content of at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, or almost 100 wt%, or 100 wt%, or from about 20 wt% to about 100 wt%, in each case based on the total weight of the particles. Each of the silica can be chemically functionalized, e.g., with bound or adsorbed chemical groups, such as bound or adsorbed organic groups. Any combination of silica can be used. The silica that forms the silica slurry and / or destabilized silica slurry may be partially or entirely a silica with a hydrophobic surface, which may be a hydrophobic silica or a silica that becomes hydrophobic through treatment of the surface (e.g. chemical treatment).The hydrophobic surface can be obtained by chemically modifying the silica particles with hydrophobizing silanes lacking ionic groups, such as bistriethoxysilylpropyltetrasulfide. Such a surface reaction on silica can be performed in a separate process step prior to dispersion or in situ within a silica dispersion. The surface reaction reduces the silanol density on the silica surface, thereby reducing the ionic charge density of the silica particle in the suspension. Suitable hydrophobic, surface-treated silica particles for use in dispersions can be obtained from commercial sources, such as Agilon® 454 Silica and Agilon® 400 Silica from PPG Industries. Silica dispersions and destabilized silica dispersions can be prepared using silica particles with low surface silanol density.Such silica can be obtained at temperatures above 150 °C by dehydroxylation, for example by means of a calcination process.

[0058] Furthermore, the silica slurry and / or destabilized silica slurry may optionally contain a small amount (10 wt% or less, based on the total weight of the particles) of any non-silica particles, such as carbon black, zinc oxide, calcium carbonate, or other particulate materials useful in rubber compositions (e.g., 95 wt% precipitated silica and 5 wt% carbon black). Any reinforcing or non-reinforcing grade of carbon black may be selected to impart the desired property to the final rubber composition.

[0059] The silica can be dispersed in aqueous liquid according to any method known to a person skilled in the art. A dispersion of particulate silica can be subjected to mechanical processing, for example, to reduce the particle size. This can be carried out before, during, or after the destabilization of the dispersion and may contribute to the destabilization to a small or large extent. The mechanical processing may include or involve grinding, crushing, comminution, pulverization, or fluid processing under high shear forces, or any combination thereof.

[0060] For example, a silica slurry can be produced by dispersing silica in a liquid using a milling process. Such a milling process reduces the size of most silica agglomerates (e.g., over 80 vol%) in the liquid to less than 10 micrometers and preferably less than 1 micrometer, the typical size range of colloidal particles. The fluid can be water, an aqueous liquid, or a non-aqueous polar liquid. The slurry can, for example, contain silica particles from about 6 wt% to about 35 wt% by weight. The size of the silica particles can be determined using a light scattering technique.Such a slurry, when prepared in water using silica particles with low residual salt content at a pH of 6 to 8, typically has a zeta potential magnitude greater than or equal to 30 mV and exhibits good stability against aggregation, gelation, and separation in a storage tank under slow stirring (e.g., stirring speed below 60 rpm). Since well-milled silica particles are generally stable in water at a pH of around 7 due to high negative charges on the silica, very high shear forces are generally required to overcome the repulsive energy barrier between the particles and induce particle agglomeration.

[0061] In an exemplary process using silica, such as HDS granules, the silica can be combined with water, and the resulting mixture passed through a colloid mill, tube mill, or the like to form a dispersion fluid. This fluid is then passed into a homogenizer, which further disperses the filler in the carrier fluid to form the slurry. Exemplary homogenizers include, but are not limited to, the Microfluidizer system, commercially available from Microfluidics International Corporation (Newton, Mass., USA). Also suitable are homogenizers such as the MS 18, MS45, and MC120 models, and series homogenizers available from APV Homogenizer Division of APV Gaulin, Inc. (Wilmington, Mass., USA). Other suitable homogenizers are commercially available and will be apparent to those skilled in the art in the field, given the advantages of the present disclosure.The optimal operating pressure across a homogenizer can depend on the actual device, the silica type, and / or the silica content. For example, a homogenizer may operate at a pressure of approximately 10 psi to approximately 5000 psi or higher, such as approximately 10 psi to approximately 1000 psi, approximately 1000 psi to approximately 1700 psi, approximately 1700 psi to approximately 2200 psi, approximately 2200 psi to approximately 2700 psi, approximately 2700 psi to approximately 3300 psi, approximately 3300 psi to approximately 3800 psi, approximately 3800 psi to approximately 4300 psi, or approximately 4300 psi to approximately 5000 psi. As mentioned previously, the dispersion of particulate silica is destabilized before the masterbatch process is carried out, and the dispersion can be destabilized by performing one of the techniques mentioned here before, during or after milling or a similar mechanical process.

[0062] Depending on the wet masterbatch process, a high silica concentration in the slurry can be used to reduce the need for removing excess water or other carriers. For the destabilized dispersion of silica particles, the liquid used can be water, another aqueous solution, or another fluid.For the destabilized dispersion, filler can be used in amounts ranging from approximately 6% to 35% by weight, from approximately 6% to 9% by weight, from approximately 9% to 12% by weight, from approximately 12% to 16% by weight, from approximately 10% to 28% by weight, from approximately 16% to 20% by weight, from approximately 20% to 24% by weight, from approximately 24% to 28% by weight, or from approximately 28% to 30% by weight, based on the weight of the destabilized dispersion. A higher silica concentration can be advantageous for the destabilized dispersion. For example, the silica concentration in the destabilized slurry can be at least 10% by weight or at least 15% by weight, based on the weight of the slurry (for example, about 12% by weight to about 35% by weight).-% or approximately 15.1 wt.% to approximately 35 wt.% or approximately 20 wt.% to approximately 35 wt.%), thereby providing, among other things, advantages such as reduced wastewater volumes, increased production rates, and / or a reduction in the plant size required for the process. Experts in the field will recognize, in view of the advantages of this disclosure, that the silica concentration (in wt. percent) of the silica slurry (and in the destabilized silicon dioxide slurry) should be adjusted with other process variables during the wet process to obtain the desired silica:rubber ratio (in phr) in the final product.

[0063] Details of a silica-containing dispersion are described below. In general, a dispersion can be a material comprising more than one phase, wherein at least one of the phases consists of, comprises, or includes finely divided phase domains, optionally in the colloidal size range. A dispersion or slurry containing silica or silica dispersion can be prepared as a stable slurry of particulate silica in aqueous liquid, wherein the charge on the particle surface prevents particle agglomeration and the dispersion is characterized by having a zeta potential magnitude of 30 mV or greater. In such dispersions, the silica particles remain in stable dispersion and / or suspension with respect to aggregation and coalescence, for example, for at least 8 hours.A stable dispersion can be characterized by the maintenance of a constant particle size and the fact that the particles do not settle or gel, or require a very long time to settle noticeably under slow or periodic stirring, for example, 8, 12, 24, or 48 hours. For instance, colloidal silica particles that are well dispersed in aqueous solution generally exhibit stability at a pH of 8 to 10. Furthermore, the silica particles remain suspended in the fluid under slow stirring of the dispersion due to the particle surface charge, particle surface polarity, pH, selected particle concentration, particle surface treatment, and combinations thereof.The liquid may be or comprise water, an aqueous mixture, or a water-miscible or partially miscible liquid, such as various alcohols, ethers, and other low-molecular-weight water-miscible solvents, preferably containing C1-C5 organic groups (e.g., ethanol, methanol, propanol, ethyl ether, acetone, and the like). As indicated above, the dispersion may, for example, comprise approximately 6 wt.% to approximately 35 wt.%, approximately 10 wt.% to approximately 28 wt.%, approximately 12 wt.% to approximately 25 wt.%, or approximately 15 wt.% to approximately 30 wt.% silica-containing particles, based on the weight of the dispersion.

[0064] A stable dispersion can be a colloidal dispersion. In general, a colloidal dispersion, or colloid, is a substance in which dispersed particles are suspended in another substance. The dispersed-phase particles have a diameter of approximately 1 nanometer to approximately 1000 nanometers, and typically about 100 nanometers to approximately 500 nanometers. In a stable colloidal dispersion, the particle size, density, and concentration are such that gravity cannot easily cause the particles to settle out of the dispersion. Colloids with a zeta potential magnitude of 30 mV or higher are generally considered stable colloidal systems. A decrease in the stability of the particles (e.g., silica) in a colloid or dispersion due to charge stabilization can be measured by the decrease in zeta potential magnitude. The particle size can be measured by a light scattering method.

[0065] A destabilized silica dispersion can be understood as a dispersion of silica in a fluid where weakened particle-particle repulsion forces allow particle clustering and the formation of a silica particle-particle network or gel once the destabilized dispersion is subjected to shear forces to an effective degree. In certain cases, mechanical shear can cause the destabilization of silica dispersions and the clustering of silica particles. The higher the degree of destabilization of the silica slurry, the lower the shear required for particle aggregation and the higher the rate of particle aggregation. For a destabilized dispersion, the dispersion can comprise approximately 6 wt% to approximately 35 wt% particulate silica (based on the weight of the dispersion), for example, approximately 8 wt% to approximately 35 wt%, approximately 10 wt% to approximately 28 wt%, and approximately 12 wt% to approximately 10 wt%.-% to about 25 wt%, from about 15 wt% to about 30 wt%. The aqueous liquid in the destabilized dispersion of silica particles can be or comprise water, an aqueous mixture, or a water-miscible or partially miscible liquid, such as various alcohols, ethers, and other low-molecular-weight water-miscible solvents, preferably with C1-C5 organic groups (e.g., ethanol, methanol, propanol, ethyl ether, acetone, and the like). To form silica elastomer composites, the stability of the silica particles in a slurry or dispersion is reduced (i.e., it is destabilized) by lowering the electrostatic energy barrier between the particles through the addition of an effective amount of a destabilizing agent, such as acid or salt, or both, before the slurry is mixed with latex.A destabilizing agent can be selected according to its ability to reduce the repulsive particle interaction between particle surfaces, which prevents particle agglomeration in the fluid.

[0066] A destabilized silica dispersion can be obtained by lowering the pH of the dispersion to a value close to the isoelectric point (approximately pH 2 for typical hydrophilic silica). For example, silica destabilization can be achieved by adding acid to lower the pH of the particulate silica dispersion to 2 to 4, thereby reducing the zeta potential magnitude of the dispersion to less than 30 mV, such as below approximately 28 mV (e.g., zeta potential magnitudes of approximately 18 mV to approximately 6 mV for formic acid as the destabilizing agent). The addition of acid and / or salt to a silica slurry can effectively reduce the stability of silica particles dispersed in water. The molar concentration of the acid or salt is usually the dominant factor determining the zeta potential of the destabilized silica slurry.In general, a sufficient amount of acid or salt or both can be used to reduce the zeta potential magnitude of the silica slurry to less than 30 mV, such as 28 mV or less, preferably 25 mV or less, in order to produce a semi-solid or solid, silica-containing, continuous rubber phase.

[0067] The amount of acid used to destabilize the silica dispersion can be such that a zeta potential magnitude of less than 30 mV is obtained in the destabilized dispersion, such as 28 mV or less, or 25 mV or lower. The acid can be at least one organic or inorganic acid. The acid can be acetic acid, formic acid, citric acid, phosphoric acid, or sulfuric acid, or any combination thereof. The acid can be or include a C1 to C4 alkyl-containing acid. The acid can be or include one having a molecular weight or weight-averaged molecular weight of less than 200, such as less than 100 MW or less than 75 MW, or of approximately 25 MW to 100 MW. The amount of acid can vary and depends on the destabilized silica dispersion. The amount of acid can vary, for example, from about 0.8 wt.% to about 7.5 wt.%.-%, for example, from about 1.5 wt% to about 7.5 wt% or more (based on the total weight of the fluid comprising the silica dispersion). If an acid is used as the sole destabilizing agent, the amount of acid can be sufficient to lower the pH of the silica dispersion by at least 2 pH units, or to at least a pH of 5 or lower, or to the pKa range of the acid(s) used, in order to reduce charge interactions between the particles.

[0068] A destabilized dispersion can be obtained by treating a dispersion containing silica with a destabilizing agent comprising one or more salts to adjust the zeta potential of the leaching to the range described above. The salt may be or include at least one metal salt (for example, from Group 1, 2, 13, or metals). The salt may be or include a calcium salt, magnesium salt, or aluminum salt. Exemplary counterions include nitrate, acetate, sulfate, and halogen ions such as chloride, bromide, iodide, and the like. The amount of salt may, for example, range from about 0.2 wt% to about 2 wt% or more, or from about 0.5 or 1 wt% to about 1.6 wt% (based on the weight of the fluid comprising the silica dispersion).

[0069] A combination of at least one salt and / or at least one acid can be used to destabilize the silica-containing dispersion.

[0070] When the destabilized silica-containing dispersion is achieved with the addition of at least one salt, the salt concentration in the destabilized dispersion can range from about 10 mM to about 160 mM, or other amounts above or below this range.

[0071] When the destabilized silica-containing dispersion is achieved with the addition of at least one acid, the acid concentration in the destabilized dispersion can be approximately 200 mM to approximately 1000 mM, for example approximately 340 mM to approximately 1000 mM, or other amounts above or below this range.

[0072] A destabilized dispersion can be prepared using silica particles treated to carry a suitable amount of positively charged surface functional groups, such that the net charges on the silica surface are sufficiently reduced to decrease the zeta potential magnitude of the dispersion to below 30 mV. As a result of such surface treatment, the net charge on the silica surface can be positive rather than negative. The positively charged functional group can be introduced to the silica surface by chemical bonding or physical adsorption. For example, the silica surface can be treated with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride either before or after the preparation of the silica dispersion. It is also possible to adsorb cationic coating agents, such as amine-containing molecules and basic amino acids, onto the silica surface.It is theoretically assumed that a positive net charge on silica particle surfaces can improve the coagulation of the latex, which comprises negatively charged rubber particles, by means of heterocoagulation.

[0073] With regard to the "second fluid," which contains at least one elastomeric latex, this fluid may comprise one or more elastomeric latexes. An elastomeric latex can be considered a stable colloidal dispersion of rubber and may contain, for example, from about 10 wt% to about 70 wt% rubber based on the total weight of the latex. The rubber may be dispersed, for example, in a fluid such as water or another aqueous liquid. The aqueous liquid content in this fluid (or the water content) may be 40 wt% or more, such as 50 wt% or more, or 60 wt% or more, or 70 wt% or higher, for example, from about 40 wt% to 90 wt% based on the weight of the fluid comprising at least one elastomeric latex. Suitable elastomeric latexes include both natural and synthetic elastomeric latexes and latex blends.Elastomeric latex can be synthetically produced, for example, by polymerizing a monomer such as styrene emulsified with surfactants. The latex should be suitable for the selected wet masterbatch process and the intended purpose or application of the final rubber product. Given the advantages of this disclosure, the selection of a suitable elastomeric latex or a suitable mixture of elastomeric latexes for use in the processes and apparatus disclosed herein is within the capabilities of a person skilled in the art.

[0074] The elastomer latex can be natural rubber or comprise natural rubber, such as a natural rubber emulsion. Examples of natural rubber latices include, but are not limited to, field latex, latex concentrate (produced, for example, by evaporation, centrifugation, or skimming), skimmed latex (for example, the supernatant remaining after producing latex concentrate by centrifugation), and mixtures of any two or more of these latices in any proportion. Natural rubber latex is typically treated with ammonia to preserve it, and the pH of the treated latex is typically in the range of 9 to 11. The ammonia content of the natural rubber latex can be adjusted and can be reduced, for example, by blowing nitrogen over or through the latex. Latex suppliers typically remove sludge from the latex by adding diammonium phosphate. They may also stabilize the latex by adding ammonium laurate.The natural rubber latex can be diluted to a desired dry rubber content (DRC). Thus, the latex used here can be desluried latex. A secondary preservative, a mixture of tetramethylthiuram disulfide and zinc oxide (TZ solution), may also be included. The latex should be suitable for the selected wet masterbatch process and for the intended purpose or application of the final rubber product. The latex is typically provided in an aqueous carrier fluid (e.g., water). The amount of aqueous carrier fluid can vary, for example, from about 30 wt% to about 90 wt% by weight. In other words, such natural rubber latexes can contain, for example, about 10 wt% to about 70 wt% rubber, or be adjusted accordingly.The selection of a suitable latex or mixture of latexes is within the capabilities of experts in the field, given the advantages of this disclosure and knowledge of industry-recognized selection rules.

[0075] Natural rubber latex can also be chemically modified in some way. For example, it can be treated to chemically or enzymatically reduce various non-rubber components, or the rubber molecules themselves can be modified with different monomers or other chemical groups such as chlorine. Epoxidized natural rubber latex can be particularly advantageous because the epoxidized rubber is thought to interact with the silica surface (Martin et al., Rubber Chemistry and Technology, May 2015 doi: 10.5254 / rct15.85940). Exemplary processes for the chemical modification of natural rubber latex are described in European patent publications Nos. 1 489 102, 1 816 144 and 1 834 980, Japanese patent publications Nos. 2006-152211, 2006-152212, 2006-169483, 2006-183036, 2006-213878, 2006-213879, 2007-154089 and 2007-154095, GB patent No. GB ​​2113692, US patent No.6,841,606 and 7,312,271 and U.S. Patent Publication No. 2005-0148723. Other methods known to those skilled in the art may also be used.

[0076] Other exemplary elastomers include, but are not limited to, rubbers, polymers (for example, homopolymers, copolymers, and / or terpolymers) of 1,3-butadiene, styrene, isoprene, isobutylene, 2,3-dialkyl-1,3-butadiene, where alkyl may be methyl, ethyl, propyl, etc., acrylonitrile, ethylene, propylene, and the like. The elastomer may have a glass transition temperature (Tg) of about -120°C to about 0°C, as measured by differential scanning calorimetry (DSC). Examples include, but are not limited to, styrene-butadiene rubber (SBR), natural rubber and its derivatives, such as chlorinated rubber, polybutadiene, and polyisoprene.Poly(styrene-co-butadiene) and the oil-reduced derivatives of any one of them. Mixtures of any of the above may also be used. The latex may be in an aqueous carrier fluid. Particularly suitable synthetic rubbers include: copolymers of styrene and butadiene comprising about 10% to about 70% by weight of styrene and about 90% to about 30% by weight of butadiene, such as a copolymer of 19 parts styrene and 81 parts butadiene, a copolymer of 30 parts styrene and 70 parts butadiene, a copolymer of 43 parts styrene and 57 parts butadiene, and a copolymer of 50 parts styrene and 50 parts butadiene; Polymers and copolymers of conjugated dienes such as polybutadiene, polyisoprene, polychloroprene and the like, and copolymers of such conjugated dienes with an ethylene-containing monomer that can be copolymerized with it, such as styrene, methylstyrene, chlorostyrene, acrylonitrile, 2-vinylpyridine, 5-methyl-2-vinylpyridine,5-Ethyl-2-vinylpyridine, 2-methyl-5-vinylpyridine, allyl-substituted acrylates, vinyl ketone, methyl isopropenyl ketone, methyl vinyl ether, alpha-methylenecarboxylic acids and their esters and amides, such as acrylic acid and dialkylacrylamide. Copolymers of ethylene and other higher alpha-olefins such as propylene, 1-butene, and 1-pentene are also suitable for this application. Mixtures of two or more types of elastomer latex, including mixtures of synthetic and natural rubber latex or of two or more types of synthetic or natural rubber, can also be used.

[0077] In addition to the elastomer, filler and coupling agent, vulcanizable elastomer composites may contain various processing aids, oil extenders, anti-degradation agents, antioxidants and / or other additives.

[0078] The amount of silica present in the elastomer composite (in parts per hundred parts rubber or phr) can range from 40 phr to approximately 180 phr, 40 phr to approximately 150 phr, 40 phr to approximately 80 phr, 40 phr to approximately 115 phr, 40 phr to approximately 100 phr, 40 phr to approximately 90 phr, 40 phr to approximately 175 phr, 40 phr to approximately 110 phr, approximately 50 phr to approximately 175 phr, or approximately 60 phr to approximately 175 phr. The elastomer composite may optionally contain a small amount of carbon black for color, conductivity, and / or UV stability, and / or for other purposes. Small amounts of carbon black contained in the elastomer composite range, for example, from approximately 0.1 wt% to approximately 10 wt%, based on the total particle weight in the elastomer composite. Any grade or type of carbon black can be used, such as reinforcing or semi-reinforcing furnace carbon black of tire quality and the like.

[0079] In any process for producing a vulcanizable elastomer composite, the process may further include, after the formation of the solid or semi-solid, silica-containing, continuous rubber phase, one or more of the following steps: - one or more holding steps or further solidification or coagulation steps to develop further elasticity; - One or more dewatering steps can be used to dewater the composite and obtain a dewatered composition; - one or more extrusion steps; - one or more calendar steps; - one or more milling steps to obtain a milled composite; - one or more granulation steps; - one or more steps of packaging the silica elastomer composite into bales to obtain a baled product or baled mixture; - one or more mixing or compounding steps to obtain a compounded composite.

[0080] As another example, after the formation of the solid or semi-solid, silica-containing, continuous rubber phase, the following sequence of steps can occur, and each step can be repeated any number of times (with the same or different settings): - one or more holding steps or further solidification or coagulation steps to develop further elasticity; - Dehydrating the composite (e.g., the elastomer composite emerging from the reaction zone) to obtain a dehydrated composite; - Mixing and compounding the dehydrated composite to obtain a compounded composite; - Milling the compounded composite to obtain a milled mixture (e.g. roller milling); - Granulating or mixing the ground mixture; - optional packaging of the mixture into bales after granulation or mixing to obtain a bale-formed mixture; - optional breaking apart and mixing of the mixture formed into balls.

[0081] In each embodiment, a coupling agent can be introduced at any of the steps (or at multiple stages or positions) as long as the coupling agent has an opportunity to be dispersed in the elastomer composite.

[0082] As just one example, the solid or semi-solid, silica-containing, continuous rubber phase exiting the reaction zone can be transferred to a dewatering extruder using a suitable device (e.g., conveyor belt or conveying system). Suitable dewatering extruders are well-known and commercially available, for example, from French Oil Mill Machinery Co. (Piqua, Ohio, USA). Alternatively or additionally, the solid or semi-solid, silica-containing, continuous rubber phase can be compressed, for example, between metal plates, to expel at least some of the aqueous fluid phase, for example, to drive out aqueous liquid, until the water content of such material is below 40% by weight.

[0083] In general, post-processing steps can include compressing the elastomer composite to remove approximately 1 wt% to approximately 15 wt% or more of an aqueous fluid phase, based on the total weight of the elastomer composite. Dewatering extruders can change the water content of the elastomer composite from, for example, approximately 40% to approximately 95% to approximately 5% to approximately 60% (e.g., from approximately 5% to approximately 10%, from approximately 10% to approximately 20%, from approximately 15% to approximately 30%, or from approximately 30% to approximately 50%), in each case based on the total weight of the composite. Dewatering extruders can be used to reduce the water content of the elastomer composite to approximately 35 wt% or other values. The optimal water content can vary depending on the elastomer used, the amount and / or type of filler, and the equipment used for masticating the dehydrated product.The elastomer composite can be dewatered to a desired moisture content, after which the resulting dewatered product can be further masticated while drying to a desired moisture content (e.g., from about 0.5% to about 10%, for example, from about 0.5% to about 1%, from about 1% to about 3%, about 3% to about 5%, or from about 5% to about 10%, preferably below 1%, in each case based on the total weight of the product). The mechanical energy applied to the material can provide an improvement in the rubber properties. For example, the dewatered product can be mechanically processed using one or more continuous mixers, internal mixers, twin-screw extruders, single-screw extruders, or roller mills.This optional mixing step may optionally have the capability to masticate the mixture and / or generate or expose a surface, thereby enabling (at least partial) the removal of any water that may be present in the mixture. Suitable masticating devices are well known and commercially available, including, for example, a Unimix Continuous Mixer and an MVX (Mixing, Deaerating, Extruding) machine from Farrel Corporation of Ansonia, CT, USA; a long continuous mixer from Pomini, Inc.; a Pomini continuous mixer; an intermeshing, co-rotating twin-rotor extruder; an extruder with non-intermeshing, counter-rotating twin rotors; Banbury mixers; Brabender mixers; intermeshing internal mixers; kneading internal mixers; continuous compounding extruders; and the biaxially grinding extruder manufactured by Kobe Steel, Ltd.; and a Kobe continuous mixer. Alternative masticating equipment will be familiar to the professional and can be used.

[0084] While the dewatered product is processed in a desired device, the device transfers energy to the material. Without being bound to any specific theory, it is assumed that the friction generated during mechanical mastication heats the dewatered product. Some of this heat is dissipated by heating and evaporating the moisture in the dewatered product. Some of the water can also be removed by compressing the material concurrently with the heating. The temperature should be high enough to rapidly evaporate the water to steam, which is released into the atmosphere and / or removed from the device, but not so high as to burn the rubber. The dewatered product can reach a temperature of approximately 130°C to 180°C, or from approximately 140°C to approximately 160°C, particularly if the coupling agent is added before or during mastication.The coupling agent may contain a small amount of sulfur, and the temperature should be kept at a sufficiently low level to prevent crosslinking of the rubber during masticating.

[0085] Optionally, additives can be combined with the dehydrated product in a mechanical mixer. Specifically, additives such as fillers (which may be the same as or different from the filler used in the mixer; examples of fillers are silica, carbon black, and / or zinc oxide); other elastomers; other or additional masterbatch premixes; antioxidants; coupling agents; plasticizers; processing aids (for example, stearic acid, which may also be used as a curing agent, liquid polymers, oils, waxes, and the like); resins; flame retardants; extender oils; and / or lubricants; and a mixture of any of these can be added in a mechanical mixer. Additional elastomers can be combined with the dehydrated product to create elastomer blends.Suitable elastomers include any of the elastomers used in the mixing process described above in latex form, and elastomers such as EPDM that are not available in latex form. They may be the same as, or different from, the elastomer in the silica-containing elastomer composite. Examples of elastomers include, but are not limited to, rubbers, polymers (for example, homopolymers, copolymers, and / or terpolymers) of 1,3-butadiene, styrene, isoprene, isobutylene, 2,3-dialkyl-1,3-butadiene (where alkyl may be methyl, ethyl, propyl, etc.), acrylonitrile, ethylene, propylene, and the like. Methods for producing masterbatch mixtures are disclosed in jointly owned US patents Nos. 7,105,595, 6,365,663 and 6,075,084 and PCT publication WO 2014 / 189826.The antioxidant (an example of a degradation inhibitor) may be an amine-type antioxidant, a phenol-type antioxidant, an imidazole-type antioxidant, a carbamate metal salt, para-phenylenediamine(s) and / or dihydrotrimethylquinoline(s), polymerized quinine antioxidants and / or wax and / or other antioxidants used in elastomer formulations. Specific examples include, but are not limited to, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD, e.g., ANTIGENE 6C, available from Sumitomo Chemical Co., Ltd., and NOCLAC 6C, available from Ouchi Shinko Chemical Industrial Co., Ltd.); "Ozonon" 6C from Seiko Chemical Co., Ltd.; polymerized 1,2-dihydro-2,2,4-trimethylquinoline (TMQ, e.g. Agerite Resin D, available from RT Vanderbilt), 2,6-di-t-butyl-4-methylphenol (available as Vanox PC from Vanderbilt Chemicals LLC), butylhydroxytoluene (BHT), and butylhydroxyanisole (BHA), and the like.Other representative antioxidants may include, for example, diphenyl-p-phenylenediamine and others, such as those disclosed in "The Vanderbilt Rubber Handbook" (1978), on pages 344-346.

[0086] The coupling agent may comprise or be one or more silane coupling agents, one or more zirconate coupling agents, one or more titanate coupling agents, one or more nitro coupling agents, or any combination thereof. The coupling agent can be bis(3-triethoxysilylpropyl)tetrasulfane (e.g., Si 69 from Evonik Industries, Struktol SCA98 from Struktol Company), bis(3-triethoxysilylpropyl)disulfane (e.g., Si 75 and Si 266 from Evonik Industries, Struktol SCA985 from Struktol Company), 3-thiocyanatopropyltriethoxysilane (e.g., Si 264 from Evonik Industries), gamma-mercaptopropyltrimethoxysilane (e.g., VP Si 163 from Evonik Industries, Struktol SCA989 from Struktol Company), gamma-mercaptopropyltriethoxysilane (e.g., VP Si 263 from Evonik Industries), zirconium dineoalkanolatodi(3-mercapto) propionato-O,N,N'-bis(2-methyl-2-nitropropyl)-1,6-diaminohexane, S-(3-(triethoxysilyl)propyl) octane thioate (e.g.NXT coupling agents from Momentive, Friendly, WV) and / or coupling agents that are chemically similar or that contain one or more of the same chemical groups. Other specific examples of coupling agents include, but are not limited to, those with the trade name VP Si 363 from Evonik Industries. It is understood that any combination of elastomers, additives, and masterbatches, for example in a kneader, can be added to the dehydrated product.

[0087] Optionally, the dewatered product can be masticated in an internal mixer such as a Banbury or Brabender mixer. The dewatered product can first be brought to a moisture content of approximately 3 wt% to approximately 40 wt%, for example, approximately 5 wt% to approximately 20 wt% or approximately 20 wt% to approximately 30 wt%. The moisture content can be reduced to the desired level by dewatering, or by first dewatering the dewatered product granules to an intermediate moisture content, and then by heating the resulting dewatered product to further reduce the moisture content, or by allowing water to evaporate from the dewatered product at room temperature, or by other methods familiar to those skilled in the field. The dewatered product can then be masticated in an internal mixer until a desired moisture level or desired mechanical energy input is achieved.The dewatered product can be masticated until it reaches a predetermined temperature, cooled, and then re-entered, once or several times, the internal mixer to transfer additional energy to the material. Examples of temperature ranges include approximately 140°C to approximately 180°C, for example, approximately 145°C to approximately 160°C, or approximately 150°C to approximately 155°C. The dewatered product can be rolled in a roller mill after each mastication in the internal mixer. Alternatively, or additionally, the dewatered product masticated in a Banbury or Brabender mixer can be further masticated in an open mill.

[0088] Optionally, the masticated product can be further processed in an open mill. The masticated product can be discharged from the continuous compounder as an elongated extrudate and cut into shorter lengths before entering the open mill. The masticated product can optionally be fed to the open mill via a conveying device. The conveying device can be a conveyor belt, a duct, a pipe, or another suitable means of transporting the masticated product from a continuous compounder to an open mill. The open mill can include a pair of rollers, which can optionally be heated or cooled to improve the mill's operation. Other operating parameters of the open mill include the gap between the rollers, the bank height (i.e., the amount of material in the gap between and on top of the rollers), and the speed of each roller.The speed of each roll and the temperature of the cooling fluid can be controlled independently for each roll. The gap can be from approximately 3 mm to approximately 10 mm or from approximately 6 mm to approximately 8 mm. The roll speed can be from approximately 15 rpm to approximately 70 rpm, and the rolls can roll against each other relative to the inlet side of the mill roll. The friction ratio, the ratio of the speeds of the collecting roll (e.g., the roll on which the masticated product collects) to the trailing roll, can be from approximately 0.9 to approximately 1.1. The cooling fluid can have a temperature of approximately 35°C to approximately 90°C, for example, from approximately 45°C to approximately 60°C, from approximately 55°C to approximately 75°C, or from approximately 70°C to approximately 80°C.In addition to controlling the operation of the open mill to achieve a desired degree of mastication and drying in the masticated product, it is also desirable for the mill's output to collect as a smooth plate on the collecting roller. While not bound to any specific theory, it is assumed that cooler roller temperatures facilitate this. The open mill can reduce the temperature of the masticated product to approximately 110°C to 140°C. The residence time of the masticated product in the mill can be determined by the roller speed, the gap, and the desired degree of mastication and drying, and can range from approximately 10 to 20 minutes for pre-masticated material, for example, in a twin-rotor mixer.

[0089] A person skilled in the art will recognize that different combinations of devices can be used for masticating and drying a solid, silica-containing, continuous rubber phase produced according to the various embodiments. Depending on the devices used, it may be desirable to operate them under conditions other than those described above in order to subject the material to varying degrees of work and drying. Additionally, it may be desirable to use more than one particular type of device, for example, an open mill or internal mixers in series, or to pass the masticated product through a given device multiple times. For example, the masticated product may pass through an open mill two or three times or more, or two, three, or more open mills in series.In the latter case, it may be desirable for each open mill to operate under different conditions, such as speed, temperature, varying (e.g., higher) energy inputs, etc. Masticated product can be passed through one, two, or three open mills after being masticated in an internal mixer.

[0090] The vulcanizable elastomer composite can be used to manufacture elastomer- or rubber-containing products. Optionally, the elastomer composite can be manufactured for use in or within various parts of a tire, such as tires, treads, sidewalls, bead cables, and cushioning rubber for retreaded tires. Alternatively or additionally, the elastomer composite can be used for hoses, seals, vibration damping components, chains, and chain pads for tracked equipment such as bulldozers, etc., Engine bearings, earthquake stabilizers, mining machinery such as screens, linings for mining equipment, conveyor belts, trough linings, slurry pump linings, slurry pump components such as impellers, valve seats, valve bodies, piston hubs, piston rods, pistons, impellers for various applications such as slurry mixers and slurry pump wheels, mill linings, cyclones and hydrocyclones, expansion joints, marine equipment such as linings for pumps (e.g. dredge pumps and outboard motor pumps), hoses (e.g. dredge hoses and outboard motor hoses) and other marine equipment, shaft seals for marine, oil industry, aerospace, and other applications, cardan shafts, linings for pipelines for conveying, for example, oil sands and / or tar sands, and other applications where abrasion resistance and / or improved dynamic properties are desired.After vulcanization, the vulcanized elastomer composite can be used in rollers, cams, shafts, pipes, profile guides for vehicles or other applications where abrasion resistance and / or improved dynamic properties are desired.

[0091] Depending on the intended use, traditional compounding techniques can be employed to combine vulcanizing agents and other additives known in the art, including those discussed above in connection with the dehydrated product, with the vulcanizable elastomer composite. Following such compounding, the material remains vulcanizable until sulfur or other crosslinking agent introduced into the elastomer composite has achieved a desired degree of crosslinking within the material, for example, after heating to a suitable temperature, e.g., 105°C, for a desired duration, e.g., the time required to achieve 90% vulcanization, determinable using a conventional rubber rheometer. Preferably, the elastomer composite achieves a swelling index of approximately 1.80 to approximately 2.20 during vulcanization, for example, approximately 1.90 to approximately 2.10 or approximately 1.95 to approximately 2.05.A person skilled in the art will recognize that the swelling index can be adjusted by selecting the accelerator, the amount of accelerator and sulfur, the vulcanization time, and the accelerator-to-sulfur ratio. The accelerator-to-sulfur ratio also influences the type of crosslinking in the rubber. Suitable accelerators, along with information on reaction kinetics, include those listed in the "Vanderbilt Rubber Handbook," published by R.T. Vanderbilt Company, Inc. (14th edition, 2010), and in the "Bayer Manual for the Rubber Industry," Bender et al., Bayer AG, 1993.

[0092] The present invention relates to a vulcanizable elastomer composite, as defined in claims 1 to 30, which is formed by one or more methods described herein.

[0093] Unless otherwise stated, all material contents described herein are to be understood as percent by weight.

[0094] The present invention is further illustrated by the following examples, which are intended to be purely exemplary. EXAMPLES

[0095] In these examples, the "field latex" was field latex (Muhibbah Lateks Sdn Bhd, Malaysia) with a dry rubber content of approximately 30% by weight. The "latex concentrate" was a latex concentrate (high ammonia content, from Muhibbah Lateks Sdn Bhd, Malaysia, or from Chemionics Corporation, Tallmadge, Ohio) that was diluted by approximately 50% to a dry rubber content of approximately 30% by weight with either pure water or water containing 0.6% to 0.7% by weight ammonia. Unless otherwise specified, the "silica" was Zeosil® Z1165 MP precipitated silica from Solvay USA Inc., Cranbury, New Jersey (formerly Rhodia).

[0096] Thermogravimetric analysis. The actual extent of the silica loading was determined by thermogravimetric analysis (TGA) according to the ISO 6231 method.

[0097] Water content of the product. The test material was cut into millimeter-sized pieces and loaded into a moisture balance (e.g., models MB35 and MB45; Ohaus Corporation, Parsippany, NJ) for measurement. The water content was measured for 20 to 30 minutes at 130°C until the test sample reached a uniform weight.

[0098] Zeta potential of the slurry. In these examples, the zeta potential of particle slurries was measured using a Zetaprobe Analyzer™ from Colloidal Dynamics, LLC, Ponte Vedra Beach, Florida, USA. The Zetaprobe directly measures the zeta potential at particle concentrations of 60 vol.% using electroacoustic multi-frequency technology. The instrument was first calibrated using KSiW (2.5 mS / cm) calibration fluid provided by Colloidal Dynamics. A 40 g sample was then placed in a 30 mL Teflon beaker (part no.: A80031) with a stirring rod, and the beaker was placed on a stirring plate (part no.: A80051) at a stirring speed of 250 rpm. The measurement was performed using the immersion probe 173 in a single-point mode with 5-point measurements at ambient temperature (approximately 25°C). The data were analyzed using ZP Version 2.14c Polar™ software provided by Colloidal Dynamics.Zeta potential values ​​can be negative or positive depending on the polarity of the charge on the particles. The "magnitude" of the zeta potential refers to its absolute value (for example, a zeta potential value of -35 mV has a higher magnitude than a zeta potential value of -20 mV). The magnitude of the zeta potential reflects the extent of electrostatic repulsion between similarly charged particles in a dispersion. The higher the magnitude of the zeta potential, the more stable the particles are in the dispersion. Zeta potential measurements were performed on slurries of particulate silica prepared as described below.

[0099] Dry silica was weighed and combined with deionized water using an 18.9 l (5 gallon) bucket and a high-shear overhead laboratory mixer with a jacketed agitator (Silverson Model AX3, Silverson Machines, Inc., East Longmeadow, MA; operated at 5200 to 5400 revolutions per minute for 30 to 45 minutes). Once the silica was coarsely dispersed in water and pumpable, the silica slurry was transferred via a peristaltic pump (Masterflex 7592-20 system - drive and control, 77601-10 pump head using I / P 73 tubing; Cole-Palmer, Vernon Hills, IL) into a mixing loop with an inline high-shear rotor stator mixer (Silverson model 150LB, downstream of the peristaltic pump, operated at 60 Hz) in a flow hopper (113.6 l (30 gallons), convex bottom vessel connection) and milled to break up silica agglomerates and any remaining silica granules.The slurry in the flow tank was then circulated at 2 L / min using the same peristaltic pump through the mixing loop for a turnover time of at least 5 to 7 times the total slurry volume (> 45 minutes) to ensure that any silica agglomerates were thoroughly ground and dispersed. An overhead mixer (IKA Eurostar power control visc-P7; IKA-Works, Inc., Wilmington, NC) with a low-shear anchor blade rotating at approximately 60 revolutions per minute was used in the flow tank to prevent gelling or sedimentation of silica particles. An acid (formic acid or acetic acid, reagent grade from Sigma Aldrich, St. Louis, MO) or salt (calcium nitrate, calcium chloride, calcium acetate, or aluminum sulfate, reagent grade from Sigma Aldrich, St. Louis, MO) was added to the slurry in the flow tank after grinding.The amount of silica in the slurry and the type and concentration of the acid or salt are given in the individual examples below.

[0100] Exemplary Process A. Where indicated in the following examples, a process using Exemplary Process A was carried out. In Process A, dry-precipitated silica and water (filtered tap water to remove particulate material) were dosed and combined, then milled in a rotor-stator mill to form a silica slurry. The particulate slurry was further milled in a feed tank using an agitator and another rotor-stator mill. The silica slurry was then transferred to a flow tank equipped with two agitators. The silica slurry was recirculated from the flow tank through a homogenizer and returned to the flow tank. An acid solution (formic acid or acetic acid, industrial grade from Kong Lange Huat Chemicals, Malaysia) or salt solution (calcium nitrate, industrial grade from [Company Name]) was added.Mey Chem Chemicals, Malaysia) was then pumped into the flow tank. The slurry was kept dispersed in the flow tank by stirring and, optionally, by means of the recirculation loop. After a suitable time, the silica slurry was introduced into a confined reaction zone (13) using the homogenizer, such as those found in . Fig. Figure 1a shows the concentration of silica in the slurry and the concentration of the acid or calcium nitrate, as specified in the particular examples below.

[0101] The latex was pumped into the reaction zone (13) through the second inlet (11) using a peristaltic pump (at less than approximately 376 kPa (40 psig) pressure). The latex flow rate was adjusted between approximately 300 and 1600 kg of latex / h to achieve a desired production rate and silica loading in the resulting product. The homogenized slurry, containing acid or salt, or a combination of acid and salt, was pumped under pressure from the homogenizer to a nozzle (1.5 mm - 3.3 mm (0.060"-0.130") inner diameter (ID)) (3a), represented by the first inlet (3) in the Fig.1 (a), so that the slurry was introduced into the reaction zone as a high-speed jet. Upon contact with the latex in the reaction zone, the jet of silica slurry, traveling at a speed of 25 m / s to 120 m / s, entrained the latex, which was flowing at 1 m / s to 11 m / s. In the examples according to embodiments of the invention, the impact of the silica slurry on the latex caused intimate mixing of the silica particles with the rubber particles of the latex, and the rubber was coagulated, thereby transforming the silica slurry and the latex into a material with a solid or semi-solid, silica-containing, continuous rubber phase, which contained 40 to 95 wt.% water enclosed in the material, based on the total weight of the material. The flow rate of the slurry (500-1800 kg / h) or the latex flow rate (300-1800 kg / h), or both, were adjusted to change the silica:rubber ratio in the final product (e.g.15-180 phr silica) and to achieve the desired production rate. Production rates (dry material basis) were 200-800 kg / hr. Specific silica contents (by TGA analysis) in the rubber after dewatering and drying of the material are listed in the examples below.

[0102] Process A-1: ​​Dewatering. The material was discharged from the reaction zone at atmospheric pressure into a dewatering extruder (The French Oil Machinery Company, Piqua, OH) at a flow rate of 200 to 800 kg / h (dry weight). The extruder (21.6 cm (8.5 in) ID) was equipped with a die plate with various hole configurations and operated at a typical rotor speed of 90 to 123 rpm, a die plate pressure of 2.86 to 9.01 MPa (400 to 1300 psig), and a power output of 80 kW to 125 kW. Within the extruder, the silica-containing rubber was compacted, and the water squeezed from the silica-containing rubber was expelled through a slotted flow channel of the extruder. Dewatered product with a typical water content of 15–60 wt.% was obtained at the extruder exit. As shown in Table 5, the dehydrated product was then subjected to process A.fed into the drying and cooling process or, as described below, further dewatered using process B. dewatering process and subsequently fed into process B. drying and cooling process.

[0103] Method A: Drying and Cooling. The dewatered product was placed in a continuous compounder (Farrel Continuous Mixer (FCM), Farrel Corporation, Ansonia, CT, with No. 7 and 15 rotors), where it was dried, masticated, and mixed with 1–2 phr of antioxidant (e.g., 6PPD from Flexsys, St. Louis, MO) and, optionally, silane coupling agent (e.g., NXT Silane, obtained from Momentive Performance Materials, Inc., Waterford, NY; 8 wt% silane by silica weight). The temperature of the FCM water jacket was set to 100°C, and the FCM outlet temperature was 140°C to 180°C. The moisture content of the masticated, dewatered elastomer composite exiting the FCM was approximately 1 wt% to 5 wt%. The product was further masticated and cooled on an open mill. A rubber sheet of the elastomer composite was cut directly from the open mill, rolled and air-cooled.

[0104] Exemplary Method B. Where indicated in the following examples, an exemplary Method B was performed. In Method B, dry silica was weighed and combined with deionized water using an 18.9 L (5-gallon) bucket and a high-shear overhead laboratory mixer with a jacketed agitator (Silverson Model AX3, Silverson Machines, Inc., East Longmeadow, MA; operated at 5200 to 5400 revolutions per minute for 30 to 45 minutes).Once the silica was coarsely dispersed in water and pumpable, the silica slurry was transferred via a peristaltic pump (Masterflex 7592-20 system - drive and control, 77601-10 pump head using I / P 73 tubing; Cole-Palmer, Vernon Hills, IL) into a mixing loop with an inline high-shear rotor stator mixer (Silverson model 150LB, downstream of the peristaltic pump, operated at 60 Hz) in a flow hopper (113.6 l (30 gallons), convex bottom vessel connection) and milled to break up silica agglomerates and any remaining silica granules. The slurry in the flow tank was then circulated at 2 L / min using the same peristaltic pump through the mixing loop for a sufficient turnover time of at least 5 to 7 times the total slurry volume (> 45 minutes) to ensure that any silica agglomerates were thoroughly ground and dispersed.An overhead mixer (IKA Eurostar power control visc-P7; IKA-Works, Inc., Wilmington, NC) with a low-shear anchor blade rotating at approximately 60 revolutions per minute was used in the running tank to prevent gelling or sedimentation of silica particles. An acid (formic acid or acetic acid, reagent grade from Sigma Aldrich, St. Louis, MO) or salt (calcium nitrate, calcium chloride, calcium acetate, or aluminum sulfate, reagent grade from Sigma Aldrich, St. Louis, MO) was added to the slurry in the running tank after milling. The amount of silica in the slurry and the type and concentration of the acid or salt are given below in Table 5 for specific examples.

[0105] The latex was pumped using a peristaltic pump (Masterflex 7592-20 System - Drive and Control, 77601-10 Pump Head using I / P 73 Tubing; Cole-Palmer, Vernon Hills, IL) through a second inlet (11) and into a similar one to that in Fig. The reaction zone (13) shown in Figure 1(b) was pumped. The latex flow rate was adjusted between approximately 25 kg / h and approximately 250 kg / h to adjust the silica:rubber ratios of the elastomer composites.

[0106] Once the silica was well dispersed in the water, the slurry was pumped from the flow tank using a diaphragm metering pump (LEWA-Nikkiso America, Inc., Holliston, MA). The pump passed through a pulsation dampener (to reduce pressure oscillation due to the diaphragm action) either into the reaction zone or, via a return loop with a T-connector, back into the flow tank. The direction of the slurry flow was controlled by two air-operated ball valves, one directing the slurry to the reaction zone and the other to the flow tank. As soon as the silica slurry could be mixed with the latex, the line feeding the first inlet (3) to the reaction zone was pressurized to 100 psig to 150 psig by closing both valves.The ball valve, which directs the slurry into the reaction zone, was then opened and the pressurized silica slurry was directed at an initial pressure of 0.79 MPa to 1.13 MPa (100 psig to 150 psig) to a nozzle 6.1 to 1.8 mm (0.020' to 0.070" ID) (3a), as in . Fig.1 (b) shown, such that the slurry was introduced into the reaction zone as a high-speed jet. Upon contact with the latex in the reaction zone, the jet of silica slurry, traveling at a speed of 15 m / s to 80 m / s, entrained the latex, which had a speed of 0.4 m / s to 5 m / s. In the examples according to one embodiment of the invention, the impact of the silica slurry on the latex caused intimate mixing of silica particles with the rubber particles of the latex, and the rubber was coagulated, thereby transforming the silica slurry and the latex into an elastomeric composite comprising the silica particles and 40 wt.% to 95 wt.% water, enclosed within a solid or semi-solid silica-containing, continuous rubber phase.Adjustments were made to the flow rates of the silica slurry (40 kg / h to 80 kg / h) or the latex flow rate (25 kg latex / h to 300 kg latex / h), or both, to modify the silica:rubber ratios in the resulting product (e.g., 15 phr to 180 phr silica) and achieve the desired continuous production rates (30 kg / h to 200 kg / h on a dry matter basis). Specific silica:rubber ratios (phr) after dewatering and drying are shown in the examples below. Method B: Drainage.

[0107] The material discharged from the reaction zone was recovered and placed between two aluminum plates in a collection tray. This "sandwich" was then inserted between two plates of a hydraulic press. Applying 17.3 MPa (2500 psig) of pressure to the aluminum plates, any water trapped in the rubber product was forced out. If necessary, the pressed material was folded into a smaller piece, and the pressing process was repeated using the hydraulic press until the water content of the rubber product was below 40 wt%.

[0108] Method B: Drying and cooling. The dewatered product was placed in a Brabender mixer (300 cm³). 3The material was introduced for drying and mastication to form a masticated, dewatered elastomer composite. Sufficient dewatered material was added to the mixer to cover the rotors. The initial mixer temperature was set to 100°C, and the rotor speed was generally 60 rpm. The water remaining in the dewatered product was converted to steam and evaporated from the mixer during the mixing process. As the material in the mixer expanded as a result of evaporation, any overflowing material was removed, if necessary. One or both of a silane coupling agent (NXT Silane, obtained from Momentive Performance Materials, Inc., Waterford, NY; 8 wt% silane based on silica weight) and / or an antioxidant (6-PPD, N-(1,3-Dimethylbutyl) -N'-phenyl- / Phenylenediamine, Flexsys, St. Louis, MO) were optionally added to the mixer if the mixer temperature was above 140°C.Once the mixer temperature reached 160°C, the material was held at 160°C to 170°C for two minutes by varying the rotor speed before being unloaded. The masticated, dewatered elastomer composite was then processed on an open mill. The moisture content of the material removed from the mill was typically less than 2% by weight. Production of rubber compounds.

[0109] The dried elastomer composite obtained by method B was compounded according to the formulation in Table A and the procedure in Table B. For silica elastomer composites to which either silane or antioxidant was added during drying, the composition of the final composite is as specified in Table A. The amounts of the silane coupling agents and / or antioxidants added during compounding were adjusted accordingly. Table A ingredient phr NR in composite 100 Silica in the composite S 6PPD* (antioxidant) 2,0 Silane (NXT Silane**) 0.08 x (phr silica) ZnO 4 Stearic acid 2 DPG*** 1,5 Cure Rite® BBTS**** 1,5 sulfur 1,5 *N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (Flexsys, St. Louis, MO) ** Active main component: S-(3-(Triethoxysilyl)propyl)octanethioate (Momentive, Friendly, WV) *** Diphenylguanidine (Akrochem, Akron, OH) **** N-tert-Butylbenzothiazole-2-sulfenamide (Smaragd Performance Materials, CuyahogaFalls, OH) NR = Natural rubber S = as indicated Table B Time (min) operation Level 1 Brabender mixer (300 cm 3 ), 65% Füllfaktor, 60U / min, 100 °C 0 Addition of rubber-silica composite 1 Add silane coupling agent if needed Hold for 2 minutes, starting at 150°C 2 Sweep and add 6PPD and mix for 1 additional minute at 150°C 3 Sweep Discharge, 160°C Six passes through roller mill Level 2 Brabender mixer (300 cm 3 ), 63% Füllfaktor, 60U / min, 100 °C 0 Addition Compound from Level 1 1 Addition of zinc oxide and stearic acid 2 Sweep 4 Discharge, 150°C Six passes through roller mill Level 3 Brabender mixer (300 cm 3 ), 63% Füllfaktor, 60U / min, 100 °C 0 Addition of compound from stage 2, sulfur and accelerator 0.5 Sweep 1 Hosting Roller grinding for one minute with a suitable belt. Discharge and execution of 6 roller grinding passes. Extraction as a sheet of the required thickness.

[0110] Vulcanization was carried out in a heated press set at 150°C for a duration (i.e. T90 + 10% of T90, where T90 is the time required to achieve 90% vulcanization) determined by a conventional rubber rheometer. Properties of rubber / silica mixtures.

[0111] The elongation at break of the solid, silica-containing, continuous rubber phase was determined by manually stretching the material obtained from the reaction zone relative to a measured length scale until it fractured. The strength properties of the vulcanized specimens under tensile stress (T300 and T100, elongation at break, tensile strength) were measured according to ASTM standard D-412. Tan δ 60° was determined using a dynamic deformation range in torsion between 0.01% and 60% at 10 Hz and 60°C. maxwas taken as the maximum value of tan δ 60 within this deformation range. Comparative example 1.

[0112] Dry-mixed silica-elastomer compounds were prepared using SMR 20 natural rubber (Hokson Rubber) and Z1165 silica, employing the formulation from Table A, which included NXT silane, and the compounding protocol from Table B. The samples were vulcanized as described above. The mechanical properties of the resulting vulcanizates are listed in Table 2. Table 1 Time (min) operation Level 1 Brabender mixer (300 cm 3 ), 65% Füllfaktor, 60U / min, 80 °C 0 Added natural rubber 0,5 Addition of silica and silane (premixed) Hold for 2 minutes at 160-170°C Sweep and add 6PPD and mix for an additional minute at 160-170°C Hosting Six passes through roller mill Level 2 Brabender mixer (300 cm 3 ), 63% Füllfaktor, 60U / min, 80°C 0 Addition Compound from Level 1 0,5 Addition of zinc oxide and stearic acid 1,5 Sweep and mix at 140-150°C for another minute. 3 Hosting Six passes through roller mill Level 3 Brabender mixer (300 cm 3 ), 63% Füllfaktor, 60U / min, 60°C 0 Addition of compound from stage 2, sulfur and accelerator 0.5 Sweep 1 Hosting Roller grinding for one minute with a suitable belt. Discharge and execution of 6 roller grinding passes. Discharge as a sheet of the required thickness. Table 2 Example No. . Silica loading (phr) T300 / T100 Tan delta 60 Tensile strength (MPa) Elongation at break (%) * Tensile strength (MPa) C1 33 5,27 0,038 33 17560 C2 38 4,53 0,079 37 21963 C3 47 4,79 0,089 32 17807 C4 51 4,38 0,099 34 20340 C5 56 4,58 0,106 31 16717 C6 61 4,23 0,121 31 16663 C7 65 4,40 0,134 29 15077 C8 70 4,05 0,153 28 14858 C9 74 4,13 0,162 26 13517 Example 2 - Reference.

[0113] A silica slurry containing 27.8 wt% Zeosil® 1165 silica was prepared according to the above description in connection with the slurry zeta potential test procedure. The slurry was then diluted with either deionized water or a supernatant obtained from ultracentrifugation of the 27.8 wt% slurry to provide a series of silica slurries with different silica concentrations. To demonstrate the relationship between the silica concentration in the slurry and the zeta potential of the slurry, the zeta potential of various silica slurries was measured. As shown in Table 3A, the zeta potential of the silica slurry appears to depend on the silica concentration when the silica slurry was prepared using deionized water.However, as shown in Table 3B, the zeta potential remains approximately the same for different silica concentrations when the suspension is diluted with the supernatant obtained from ultracentrifugation of the 27.8 wt% suspension. Table 3A Zeta potential of silica slurry prepared using deionized water. Silica concentration in slurry (w / w) 6% 10% 15% 20% 22% 25% Zeta potential (mV) -46,4 -42,7 -39,6 -36,2 -34,7 -32,3 pH 5,19 5,04 4,92 4,86 4,83 4,77 Table 3B Zeta potential of silica slurry prepared by diluting a 27.8 wt% silica slurry using the supernatant of the 27.8 wt% silica slurry. Silica concentration in slurry (w / w) 6% 22% Zeta potential (mV) -31.5 -31,4 pH 4,86 4,79

[0114] This result shows that when such silica slurries are diluted with deionized water, the increase in zeta potential magnitude is mainly due to a reduction in the ionic strength of the slurry. It is assumed that the ions in the silica slurry originate from residual salts in the silica, which are present from the manufacturing process of the silica particles. The high zeta potential magnitude of the silica slurries (all above 30 mV) indicates that the silica has high electrostatic stability in the slurry. Example 3 - Reference.

[0115] The effect of adding salt or acid to silica slurries at various concentrations on the zeta potential of these slurries is shown in Table 4. Slurries were prepared in deionized water according to the slurry zeta potential test procedure described above. The data summarized in Table 4 illustrate the dependence of the zeta potential of the silica slurries and destabilized silica slurries on the silica concentration, salt concentration, and acid concentration. The addition of salt or acid to the silica slurry reduces the zeta potential magnitude and thus the stability of the silica slurry. As shown in Table 4, the zeta potential mostly depends on the concentration of the salt or acid in the slurry or destabilized slurry, and not on the silica concentration. Table 4 Zeta potential of slurries and destabilized silica at different slurry concentrations, salt concentrations and acid concentrations. Silica concentration in excipients (wt%) [CaCl 2 ](mM) [Acetic acid] (mM) [Formic acid](mM) Zeta(mV) pH 22,0 0 0 0 -34,4 4,80 6,0 0 0 0 -45,0 NB 22,0 10,6 0 0 -24,2 4,49 22,0 29,7 0 0 -17,0 4,27 22,0 51,1 0 0 -14,6 4,17 22,0 105 0 0 -9,2 NB 22,0 155 0 0 -6,4 NB 6,0 4,6 0 0 -29,9 NB 6,0 10,4 0 0 -23,4 NB 6,0 27,6 0 0 -18,5 NB 6,0 46,4 0 0 -15,4 NB 6,0 140 0 0 -7,7 NB 22,0 0 98 0 -23,6 3,72 22,0 0 192 0 -21,4 3,65 22,0 0 564 0 -17,1 3,26 22,0 0 1857 0 -12,7 NB 6,0 0 27 0 -33,6 3,84 6,0 0 45 0 -29,9 3,68 6,0 0 174 0 -22,1 3,38 6,0 0 431 0 -18,9 3,61 22,0 0 0 118 -15,3 3,17 22,0 0 0 197 -14,2 2,96 22,0 0 0 731 -10,7 2,46 22,0 0 0 1963 -6,5 2,04 6,0 0 0 36 -17,7 3,07 6,0 0 0 42 -17,4 3,04 6,0 0 0 168 -14,6 2,62 6,0 0 0 456 -11,4 2,29 22,0 10,7 0 130 -12,9 3,04 22,0 26,6 0 248 -9,0 2,78 22,0 101 0 978 -3,1 2,10 6,0 4,7 0 36 -15,9 3,12 6,0 46,4 0 224 -10,1 2,41 NB = not determined.

[0116] The results in Table 4 illustrate the dependence of the zeta potential of silica slurries and destabilized silica slurries on the acetic acid and silica concentrations. The data show that the zeta potential values ​​depend more strongly on the acid concentration than on the silica concentration. A similar relationship between the zeta potential and the acid and silica concentrations is observed for formic acid. At a given concentration, formic acid reduces the zeta potential magnitude more than acetic acid. As shown in Table 4, a combination of formic acid and calcium chloride effectively reduces the zeta potential magnitude. The results in Table 4 demonstrate that the stability of the silica particles in the slurry can be effectively reduced by the addition of destabilizing agents, such as acid or salt, or a combination of acid and salt.Similar results were observed for calcium nitrate and calcium acetate. Example 4 - Reference.

[0117] In this example, the importance of destabilizing the silica particle dispersion prior to contacting the silica dispersion with elastomer latex was demonstrated. Specifically, four experiments were performed using the mixing device (c) in Fig. 1 carried out, which is equipped with three inlets (3, 11, 14) for feeding up to three fluids into a limited reaction zone (13), so that one fluid hits the other fluids as a high-speed jet at a speed of 15 m / s to 80 m / s at a 90° angle (see Fig.1 (c)). In three of the four experiments, the silica was milled according to procedure B described above, and acetic acid was optionally added as described below in Examples 4-A to 4-D. The slurry or destabilized slurry was then pressurized to 0.79 MPa to 1.13 MPa (100 psig to 150 psig) and introduced through inlet (3) into the confined reaction zone at a volumetric flow rate of 60 liters per hour (l / h) such that the slurry or destabilized slurry was introduced into the reaction zone as a high-velocity jet at 80 m / s. Simultaneously, natural rubber latex concentrate (60CX12021 Latex, 31 wt% dry rubber content from Chemionics Corporation Tallmadge, Ohio; diluted with deionized water) was introduced into the second inlet (11) by a peristaltic pump with a volume flow rate of 106 l / h and a velocity of 1.8 m / s.These flow rates were selected and adjusted to produce an elastomeric composite product containing 50 parts per hundred weight dry rubber (phr) of silica. The silica slurry or destabilized silica slurry and latex were mixed by combining the slow latex stream with the high-speed jet of silica slurry or destabilized slurry, entrained by the latex flow in the jet of silica slurry or destabilized silica slurry at the point of impact. The production rate (based on dry material) was set to 50 kg / h. Specific actual silica:rubber ratios in the rubber compounds produced by the process are shown in the examples below. TGA was performed after drying according to Process B. Example 4-A - Reference:

[0118] First fluid: A destabilized aqueous dispersion of 25 wt% silica with 6.2 wt% (or 1.18 M) acetic acid was prepared as described above in Procedure B. The zeta potential of the destabilized slurry was -14 mV, indicating that the slurry was significantly destabilized by the acid. The destabilized silica slurry was continuously pumped under pressure into the first inlet (3).

[0119] Second fluid: Elastomer latex was fed into the reaction zone through the second inlet (11).

[0120] The first fluid collided with the second fluid in the reaction zone.

[0121] Results: A liquid-to-solid phase inversion occurred in the reaction zone as soon as the destabilized silica slurry and latex were intimately mixed by the entrainment of the low-velocity latex flow in the high-velocity jet of the destabilized silica slurry. During entrainment, the silica was thoroughly dispersed in the latex, and the mixture coagulated into a solid phase containing 70 wt% to 85 wt% water. As a result, a stream of a solid silica-containing, continuous rubber phase in a worm- or rope-like shape was obtained at the outlet of the reaction zone (15). The composite was elastic and could be stretched to up to 130% of its original length without breaking. TGA analysis of the dried product showed that the elastomeric composite contained 58 phr of silica. Example 4-B - Reference:

[0122] First fluid: A destabilized aqueous dispersion of 25 wt% silica with 6.2 wt% acetic acid was prepared according to procedure B described above. The zeta potential of the slurry was -14 mV, indicating that the slurry was significantly destabilized by the acid. The destabilized silica slurry was continuously pumped under pressure into the first inlet (3).

[0123] Second fluid: Elastomer latex was introduced into the reaction zone through the second inlet (11).

[0124] Third fluid: Deionized water was injected into the reaction zone through the third inlet (14) at a volume flow rate of 60 I / h and a velocity of 1.0 m / s.

[0125] The three fluids met and collided in the reaction zone.

[0126] Results: A liquid-to-solid phase inversion occurred in the reaction zone, and a solid or semi-solid, silica-containing, continuous rubber phase in a rope- or worm-like form was recovered from the reaction zone outlet. A significant amount of turbid liquid containing silica and / or latex flowed out of the outlet with the solid or semi-solid, silica-containing, continuous rubber phase (7). The silica-containing continuous rubber phase contained approximately 70 wt% to approximately 75 wt% water, based on the weight of the composite. TGA analysis of the dried product showed that the elastomer composite contained 44 phr of silica. Thus, the addition of water through the third inlet had a detrimental effect on the process, as a product with a low silica content (44 phr as opposed to 58 phr in Example 4-A) and significant waste products were obtained. Example 4-C - Reference:

[0127] First fluid: A 10 wt% aqueous acetic acid solution without silica was prepared. A continuous supply of the acid solution was pumped into the reaction zone through the third inlet (14) at a velocity of 1.0 m / s at the time of entry into the reaction zone using a peristaltic pump at a volume flow rate of 60 l / h.

[0128] Second fluid: Elastomer latex was fed into the reaction zone via the second inlet (11) by a peristaltic pump at a speed of 1.8 m / s and a volume flow rate of 106 I / h.

[0129] The two fluids met and collided in the reaction zone.

[0130] Results: A solid, worm-like, sticky rubber phase was formed. TGA analysis of the dried product showed that the solid rubber phase contained no silica. Example 4-D - Reference:

[0131] First fluid: An aqueous dispersion of 25 wt% silica without acetic acid was prepared according to procedure B described above. The silica slurry was continuously pumped under pressure into the first inlet (3) at a volumetric flow rate of 60 l / h and at a velocity of 80 m / s at the point of entry into the reaction zone. The zeta potential of the slurry was -32 mV, indicating that the silica was stably dispersed in the slurry. Thus, in this example 4-D, the silica slurry was not destabilized by the addition of acid to the slurry prior to the introduction of the latex fluid.

[0132] Second fluid: Elastomer latex was fed into the reaction zone via the second inlet (11) by a peristaltic pump at a speed of 1.8 m / s and a volume flow rate of 106 I / h.

[0133] Third fluid: After an initial period of continuous flow of the first and second fluids, a 10 wt% aqueous acetic acid solution was injected into the reaction zone through the third inlet (14) at a volume flow rate that was increased from 0 l / h to 60 l / h and a velocity that was increased from 0 m / s to 1.0 m / s. All three liquids collided and mixed in the reaction zone.

[0134] Results: Initially, prior to acid injection, no silica-containing continuous rubber phase was formed, and only turbid liquid emerged from the outlet of the reaction zone (15). After acid injection into the reaction zone (13), the formation of a worm-like, semi-solid, silica-containing continuous rubber phase began when the flow of acetic acid through the third inlet was increased from 0 l / h to 60 l. The material flowing from the outlet still contained a significant amount of turbid liquid, indicating a substantial amount of waste. TGA analysis of the dried product showed that the silica-containing continuous rubber phase formed in this trial contained only 25 phr of silica.Based on the chosen production conditions and the amount of silica used, if the silica had been substantially incorporated into the silica-containing rubber phase as in Example 4-A, the result would be a silica-containing rubber phase containing more than 50 phr of silica.

[0135] These experiments demonstrate that the silica slurry must be destabilized prior to initial contact with the elastomer latex to achieve the desired silica-containing, continuous rubber phase. Example 4-A achieved what was considered efficient silica trapping within the solid, silica-containing, continuous rubber phase, while Example 4-D illustrates a comparative procedure using an initially stable silica slurry, which shows less than half the effectiveness of Example 4-A, where an initially destabilized silica slurry is used. The observation of a cloudy liquid exiting the reaction zone exit point indicates insufficient mixing of the silica with the latex and a lower proportion of trapped silica in the continuous rubber phase.It is suspected that in the comparative processes 4B and 4D, the destabilization of the fluids during mixing was insufficient. The results further show that poor silica capture occurs when additional fluid is added while the first and second fluids are being mixed, and such process conditions generate undesirable amounts of waste. Example 5.

[0136] In these examples, the processes for producing elastomer composites according to various embodiments of the invention were demonstrated using either process A or process B as described above. Fig. The apparatus shown in Figure 1 (either (a) or (b)) was operated under various conditions as described in Table 5. The operating conditions were selected to obtain a solid or semi-solid, silica-containing, continuous rubber phase with the silica-to-rubber ratios specified in Table 5. Table 5 Example No. . Procedure A / B Silica a in addition (wt%) Rubber latex b (DRC, wt.%) NH 3 in latex (wt%) Salt type Salt wt.% in salt . Acid type Acidity wt% in solution . Acid / NH 3 Molecular behavior . 1* B 25,0% 31,0% 0,27% CaCl2 1,00% Vinegar- 3,8% 1,47 2* B 25,0% 31,0% 0,27% CaCl2 1,00% Vinegar- 3,8% 1,47 3** B 25,0% 31,0% 0,27% CaCl2 1% Vinegar- 1,8% 1,29 4* B 25,0% 31,0% 0,27% CaCl2 1% Vinegar- 1,8% 1,29 5** B 25,0% 31,0% 0,27% CaCl2 1% Vinegar- 1,8% 1,29 6** B 25,0% 31,0% 0,27% N / A 0 Vinegar- 1,8% 1,29 7* B 25,0% 31,0% 0,27% N / A 0 Vinegar- 1,8% 1,29 8** B 25,0% 31,0% 0,27% N / A 0 Vinegar- 1,8% 1,29 9** B 25,0% 31,0% 0,27% N / A 0 Ants 1,5% 2,20 10* B 25,0% 31,0% 0,27% N / A 0 Ants 1,5% 2,20 11* B 25,0% 31,0% 0,27% N / A 0 Ants 1,5% 2,20 12** B 25,0% 31,0% 0,27% CaCl2 1% N / A 0 0,00 13** B 25,0% 31,0% 0,27% CaCl2 1% N / A 0 0,00 14** B 25,0% 31,0% 0,27% CaCl2 1% N / A 0 0,00 15* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Vinegar- 1,8% 1,29 16* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Vinegar- 1,8% 1,29 17* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Vinegar- 1,8% 1,29 18** B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% N / A 0 0,00 19* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% N / A 0 0,00 20* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% N / A 0 0,00 21* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,40 22* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,40 23* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,40 24* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,78 25* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,78 26* B 25,0% 31,0% 0,27% Ca(NO3)2 0,35% Ants 1,5% 1,78 27** B 25,0% 30,5% 0,27% Ca(NO3)2 0,75% N / A 0 0.00 28** B 25,0% 30,5% 0,27% Ca(NO3)2 0,75% N / A 0 0,00 29* B 25,0% 30,5% 0,27% Ca(NO3)2 0,75% N / A 0 0,00 30* B 25,0% 30,5% 0,27% Ca(NO3)2 0,75% N / A 0 0,00 31** B 20,0% 30,5% 0,27% Ca(NO3)2 0,50% N / A 0,00 32* B 20,0% 30,5% 0,27% Ca(NO3)2 1% N / A 0,00 33* B 25,0% 33,0% 0,60% Ca(NO3)2 0,75% N / A 0,00 34* A 20,0% 31,9% 0,53% Ca(NO3)2 1% N / A 0 0,00 35* A 20,0% 31,9% 0,53% Ca(NO3)2 1% N / A 0 0,00 36* A 10,0% 31,9% 0,53% Ca(NO3)2 0,5% N / A 0 0,00 37* A 10,0% 31,9% 0,53% Ca(NO3)2 0,5% N / A 0 0,00 38* A 20,0% 32,7% 0,35% Ca(NO3)2 1% N / A 0,00 39* A 16,0% 31,9% 0,53% Ca(NO3)2 1% N / A 0,00 40** A 18,5% 30,6% 0,70% Ca(NO3)2 0,75% N / A 0 0,00 41** A 18,5% 30,6% 0,70% Ca(NO3)2 0,75% N / A 0 0,00 42* A 18,5% 30,6% 0,70% Ca(NO3)2 0,75% N / A 0 0,00 43* A 16,5% 32,8% 0,66% N / A Vinegar- 3,61% 2,46 44* A 16,5% 30,6% 0,68% N / A Vinegar- 3,61% 2,23 45* A 28,0% 30,6% 0,68% Ca(NO3)2 1% N / A 0,00 46* A 28,0% 30,6% 0,68% Ca(NO3)2 1% N / A 0,00 47* A 28,0% 30,6% 0,68% Ca(NO3)2 1% N / A 0,00 48* B 25,0% 30,5% 0,27% CaCl2 0,60% N / A 0,00 49* B 25,0% 31,0% 0,27% N / A Ants 2,50% 2,31 50* B 25,0% 31,0% 0,27% N / A Ants 2,50% 2,93 51* B 25,0% 31,5% 0,67% N / A Vinegar- 5,18% 1,78 52* B 25,0% 30,9% 0,30% CaCl2 1,00% N / A 0,00 53* B 25,0% 30,9% 0,30% CaCl2 1,00% N / A 0,00 54* B 25,0% 30,9% 0,30% N / A Vinegar- 2,34% 2,17 55* B 25,0% 30,9% 0,30% CaCl2 1,45% N / A 0,00 56* B 25,0% 30,9% 0,30% N / A Vinegar- 2,4% 1,53 57** B 25,0% 30,9% 0,30% N / A Vinegar- 2,4% 1,95 N / A = not applicable * Reference ** Invention. a. In Reference Examples 32 and 33 and in Example 40, Agilon 454 Silica (silica hydrogel treated with silane coupling agent, obtained from PPG Industries Inc.) was used. In Reference Examples 50 and 51, Zeosil® 175gr Silica (conventional silica hydrogel, obtained from Solvay SA) was used. In all other examples, Zeosil® Z1165 MP precipitated silica was used. b. In reference examples 34, 39, 44 and 52, field latex was used, and in all other examples, latex concentrate was used. Table 5 (continued) Example No. . Surcharge to MBRate(L / hr) c Latex to MBrate(L / hr) c Inlet nozzle speed (m / s) d Zeta potential (estimated) (mV) e Relationship to Latex(v / v) Tats.SiO 2 loading Drying method f Addition of AO or silane during drying? Tensile strength (MPa) T300 / T100 average tan delta60°C Elongation at break (%)*Tensile strength (MPa) 1* 60 189 29 -4,7 0,317 36 B No 34,4 6,46 0,031 18145 2* 60 189 29 -4,7 0,317 36 B No 33,9 5,81 0,037 19266 3** 60 103 29 -7,4 0,581 51 B No 30,5 5,93 0,050 16522 4* 60 103 29 -7,4 0,581 50 B AO and Silane 33,3 5,65 0,057 19304 5** 60 103 29 -7,4 0,581 50 B Silane 32,3 6,09 0,049 17313 6** 60 103 29 -19,6 0,581 74 B No 29,5 6,40 0,092 16349 7* 60 103 29 -19,6 0,581 74 B AO and Silane 29,2 5,37 0,109 15752 8** 60 103 29 -19,6 0,581 75 B Silane 28,6 5,11 0,081 13776 9** 60 67 29 -11,9 0,894 71 B No 30,7 6,35 0,084 16306 10* 60 67 29 -11,9 0,894 75 B AO and Silane 29,2 4,73 0,120 15096 11* 60 67 29 -11,9 0,894 86 B Silane 27,6 4,54 0,173 13321 12** 60 103 29 -9,5 0,581 76 B No 24,2 5,44 0,071 9575 13** 60 103 29 -9,5 0,581 77 B AO and Silane 25,6 4,87 0,078 10286 14** 60 103 29 -9,5 0,581 76 B Silane 28,0 5,39 0,069 12731 15* 60 103 29 -7,8 0,581 42 B No 31,9 6,16 0,033 17130 16* 60 103 29 -7,8 0,581 43 B AO and Silane 34,0 5,36 0,041 19448 17* 60 103 29 -7,8 0,581 43 B Silane 34,0 5,77 0,039 19176 18** 60 103 29 -18,8 0,581 57 B No 30,6 6,24 0,061 16497 19* 60 103 29 -18,8 0,581 55 B AO and Silane 31,7 5,75 0,065 17387 20* 60 103 29 -18,8 0,581 56 B Silane 30,9 6,08 0,065 16862 21* 60 103 29 -10,8 0,581 41 B No 31,4 6,34 0,053 16140 22* 60 103 29 -10,8 0,581 42 B No 33,0 5,65 0,053 18744 23* 60 103 29 -10,8 0,581 42 B No 33,9 5,78 0,051 19120 24* 60 81 29 -10,8 0,740 42 B No 33,8 5,95 0,056 20449 25* 60 81 29 -10,8 0,740 44 B No 34,8 5,79 0,065 20497 26* 60 81 29 -10,8 0,740 48 B No 33,8 6,16 0,075 19976 27** 60 82 75 -13,9 0,728 72 B No 27,2 5,68 0,093 13086 28** 60 59 75 -13,9 1,009 86 B No 25,4 6,04 0,124 11083 29* 60 82 19 -13,9 0,728 62 B No 29,7 6,01 0,091 15549 30* 60 64 19 -13,9 0,936 74 B No 25,8 5,34 0,113 12006 31** 60 64 76 -3,1 0,936 73 B No 27,4 6,02 0,097 14198 32* 60 64 76 -1,8 0,936 49 B No 33,1 5,91 0,072 19234 33* 60 76 75 -13,9 0,786 68 B No 27,6 5,27 0,148 14175 34* 828 697 75 -12,2 1,187 55 C No 27,4 5,26 0,068 14735 35* 828 1078 75 -12,2 0,768 40 C No 33,5 5,43 0,059 20208 36* 950 379 78 -17,1 2,506 64 C No 27,8 5,01 0,072 14186 37* 1425 690 75 -17,1 2,064 50 C No 30,1 5,32 0,060 16182 38* 738 688 76 -12,2 1,073 52 C No 27,7 5,13 0,059 13789 39* 644 425 78 -1,8 1,517 68 C No 28,9 4,82 0,105 16244 40** 788 1541 50 -14,1 0,512 74 C No 34,4 5,54 0,025 19367 41** 1079 1342 68 -14,1 0,804 44 C No 31,6 6,08 0,037 16527 42* 1079 1342 68 -14,1 0,804 44 A, by means of FCM (no open mill) No 30,5 6,20 0,060 15403 43* 800 564 41 -16,5 1,419 49 C No 31,1 5,26 0,095 16084 44* 800 603 41 -16,5 1,326 37 C No 33,3 5,71 0,061 18387 45* 950 1384 58 -12,0 0,687 47 C No 30,4 6,02 0,054 14789 46* 950 1384 58 -12,0 0,687 47 C, Drain once (repeated) No 32,7 6,00 0,055 17418 47* 950 1384 58 -12,0 0,687 47 C, Drain twice No 27,9 5,82 0,050 13178 48* 60 68 75 -12,8 0,884 50 B No 32,0 5,32 0,074 18583 49* 60 103 75 -10,6 0,581 41 B No 29,5 6,02 0,048 14114 50* 60 81 75 -10,6 0,740 60 B No 27,4 5,81 0,081 13283 51* 60 87 19 -14,5 0,692 63 B No 27,4 4,93 0,084 13399 52* 60 78 29 -9,5 0,772 70 B No 26,2 5,73 0,100 13833 53* 60 78 29 -9,5 0,772 70 B No 27,5 5,44 0,100 14733 54* 60 72 29 -18,4 0,837 68 B No 27,8 5,57 0,094 15080 55* 60 104 75 -7,2 0,579 55 B No 24,0 5,96 0,070 14538 56* 60 104 75 -18,3 0,579 52 B No 28,8 5,65 0,057 15114 57** 60 81 75 -18,3 0,737 79 B No 24,9 5,08 0,109 11965 * reference ** invention c. Slurry and latex flow rates are the volume flows of the silica-soot slurry or the latex fluid upon arrival in the reaction zone in L / h. d. The inlet nozzle velocity is the velocity of the silica slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before contact with latex. e. Zeta potential values ​​were estimated by interpolation of experimentally determined curves of the zeta potential dependence on the concentration of the salt or acid of the suspensions at the same silica degree. f. A and B denote drying and dewatering processes A and B, as described above. “C” means dewatering according to process A, followed by further dewatering and drying according to process B. A repetition of the dewatering process denotes a repetition of dewatering according to process A.

[0137] In all examples, the selected operating conditions resulted in a solid, silica-containing, continuous rubber phase in an approximately cylindrical shape. The product contained a large amount of water, was elastic and compressible, and expelled water upon manual compression while maintaining its solids content. Silica particles were observed to be uniformly distributed throughout the continuous rubber phase, and this product was essentially free of free silica particles and larger silica grains on both the outer and inner surfaces.To form the solid, silica-containing, continuous rubber phase, not only did the silica have to be destabilized (for example, by prior treatment with acids and / or salts), but the flow rates of the destabilized silica slurry relative to the latex also had to be adjusted. This was necessary to achieve both a desired silica:rubber ratio (phr) in the elastomer composite and to match the degree of destabilization of the slurry with the mixing rate of the slurry and latex and with the coagulation rate of the latex rubber particles. Through such adjustments, after the latex was entrained with the silica slurry and the silica particles were intimately distributed within the rubber, a solid or semi-solid continuous phase was formed within the latex within a fraction of a second after the fluids were combined in the limited volume of the reaction zone.Thus, the process yielded unique silica elastomer composites by means of a continuous fluid impact step with sufficient speed, selected fluid solid concentrations and volumes, and adjusted fluid flow rates to effect a uniform and intimate distribution of the fine silica in the latex and, parallel to this distribution, the phase inversion of the rubber from liquid to solid. Comparative example 6.

[0138] In these comparative examples, the same basic steps and apparatus as described for Example 5 were used. However, the combination of the selected process conditions for each of the comparative examples in Table 6 did not result in the formation of a solid or semi-solid continuous rubber phase, and a silica-elastomer composite could not be produced. Table 6 below lists the concentration of silica in the suspension, and the concentration of acetic acid or calcium nitrate, if present, as well as other details of these examples. Table 6 Comparative examples Procedure A / B Silica concentration in exfoliation (wt%) Latex type Rubber content of the latex (DRC) (wt%) Latex wt% NH 3 (wt.%) Salt type Salt concentration in liquid (wt%) Acetic acid concentration in solution (wt%) Acid / NH 3 Molecular behavior . 6-1 A 18,5 Concession 30,6 0,70 Ca(NO3)2 0,22 N / A 0 6-2 A 18,5 Concession 30,6 0,70 Ca(NO3)2 0,48 N / A 0 6-3 A 20,0 Field- 32,7 0,35 Ca(NO3)2 1 N / A 0 6-4 A 20,0 Field- 32,7 0,35 Ca(NO3)2 1,3 N / A 0 6-5 A 10,0 Field- 32,7 0,35 Ca(NO3)2 0,65 N / A 0 6-6 A 20,0 Concession 31,9 0,53 N / A 0 4,70 0,66 6-7 A 20,0 Field- 32,7 0,33 N / A 0 2,80 0,98 6-8 B 25 Concession 31 0,27 N / A 0 0 0,00 6-9 A 18,5 Concession 30,6 0,70 N / A 0 0 0,00 6-10 A 18,5 Concession 30,6 0,70 N / A 0 0 0,00 6-11 B 20 Concession 30,5 0,27 N / A 0 0 0,00 6-12 A 16,0 Concession 31,9 0,53 N / A 0 0 0,00 Table 6 (continued) Comparative example Zeta potential (estimate) a (mV) Inlet nozzle speed . b (m / s) Silica / rubber ratio (phr) Flow rate increase . c (L / hr) Latex flow rate c (L / hr) Ratio of flow rate to latex (v / v) 6-1 -22,0 65 50 818 1118 0,73 6-2 -17,0 50 30 792 1807 0,44 6-3 -12,2 76 40 738 1289 0,57 6-4 -10,6 76 40 738 1289 0,57 6-5 -15,4 78 60 950 524 1,81 6-6 -15,1 76 20 630 2255 0,28 6-7 -17,6 76 25 630 1761 0,36 6-8 -32,0 75 50 60 114 0,53 6-9 -37 82 30 792 1807 0,44 6-10 -37 85 50 818 1118 0,73 6-11 -4,8 76 70 60 64 0,94 6-12 -7,9 67 50 552 619 0,89 N / A = not applicable. a. Zeta potential values ​​were estimated by interpolation of experimentally determined curves of the zeta potential dependence on the concentration of the salt or acid of the suspensions at the same silica degree. b. The inlet nozzle velocity is the velocity of the silica slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before contact with latex. c. Slurry and latex flow rates are the volume flows of the silica-soot slurry or the latex fluid upon arrival in the reaction zone in L / h. d. In Examples 6-11 and 6-12, Agilon® 454 Silica was used.

[0139] Comparative Examples 6-8, 6-9, and 6-10 show that, without prior destabilization of the silica in the slurry, no silica-containing continuous rubber phase was produced, even when the remaining process steps were carried out using preferred manufacturing processes for elastomer composites according to embodiments of the present invention. Comparative Examples 6-1, 6-2, 6-3, 6-4, 6-5, 6-6, and 6-7 show that, even with prior destabilization of the silica in the slurry (zeta potential of the silica below 25 mV), a silica-containing continuous rubber phase could not be produced by combining the relative volume flows and the degree of dilution of the destabilizing agent (e.g., Ca(NO3)2 or acetic acid) in the reaction zone when the fluids were mixed.Without being bound to any theory, it is theoretically assumed that such a low concentration of the destabilizing agent in the slurry-latex mixture in the reaction zone can reduce the coagulation rate of latex-rubber particles, preventing the formation of a continuous rubber phase within the short residence time in the reaction zone. In comparative example 6-1, with 18.5 wt% destabilized silica slurry and 30.6 wt% DRC latex concentrate, a relative flow ratio of slurry to destabilized latex was set to 0.73 (V / V) to deliver a silica-to-rubber ratio of 50 phr to the reaction zone.It is theoretically assumed that, under such relatively low volumetric flow conditions, the latex-rubber particles could not coagulate from the destabilized slurry to the latex within the residence time of the mixture in the reaction zone of 0.48 seconds, whereby the initial concentration of Ca(NO3)2 was diluted by 58% from 14.8 mM in the destabilized silica slurry to 6.2 mM in the reaction zone. Thus, it was not possible to produce a solid or semi-solid, silica-containing, continuous rubber phase comprising 50 phr of silica under these conditions. However, when a higher salt concentration (e.g., 0.5 wt% for Example 5-37 according to the invention compared to 0.22 wt% for Comparative Example 6-1) was used (zeta potential of -17.1 mV vs.When the slurry-to-latex volumetric flow rate was set to -22 mV and the slurry-to-latex volumetric flow rate ratio was adjusted to 2.1 to produce 50 phr silica-containing rubber, a suitable product was obtained. Comparative Example 6-3 shows that with a setting of 40 phr silica and a slurry-to-destabilized field latex volumetric flow rate ratio of 0.57 (V / V), a solid, silica-containing, continuous rubber phase cannot be produced. Higher slurry-to-latex volumetric flow rate ratios would result in less dilution of the salt in the reaction zone than in Comparative Example 6-3, thus enabling the production of a solid, silica-containing, continuous rubber phase.

[0140] The salt concentration in the 18.5% destabilized silica slurry of Comparative Example 6-2 was 0.48%, with a zeta potential of -17 mV, indicating a similar degree of destabilization to that of Invention Examples 5-41 (-14.1 mV). However, at the relatively low volumetric flow rate selected for Comparative Example 6-2, with a production setting of 30 phr silica content using latex concentrate, no solid, continuous rubber phase containing silica was formed. Without wishing to be bound by any theory, it is assumed that in comparative example 6-2, excessive dilution of the salt and / or destabilized silica slurry by latex concentrate in the reaction zone reduced the coagulation rate of the rubber-latex particles in the reaction zone to such an extent that a coherent, continuous rubber phase could not be formed within the residence time of 0.36 seconds in the reaction zone.

[0141] When field latex was mixed with a 10 wt% silica slurry destabilized with 0.65% Ca(NO3)2 (zeta potential at -15.4 mV), no solid, continuous rubber phase containing silica was produced in Comparative Example 6-5 at a silica-to-rubber ratio of 60 phr and a slurry-to-latex flow rate ratio of 0.57. These conditions do not supply sufficient salt and / or destabilized slurry to the reaction zone for rapid coagulation of the rubber latex particles in the reaction zone. In general, either the degree of destabilization of the silica slurry and / or the slurry-to-latex flow rate ratio, which were appropriate for coagulation of the latex concentrate, were insufficient to coagulate field latex.

[0142] Similar results were obtained when acid was used to destabilize the silica slurry of comparison examples 6-6 and 6-7. When acids were used as the sole means of destabilizing the silica slurry, there was a preferred acid-to-ammonia molar ratio threshold in the mixture of the slurry and latex in the reaction zone, below which a solid or semi-solid, silica-containing, continuous rubber phase did not form in the reaction zone. In these experiments, the desired acid-to-ammonia molar ratio threshold was always higher than 1.0, resulting in an acidic pH of the product exiting the reaction zone. In the case of comparison examples 6-6 and 6-7, relatively low slurry-to-latex volume flow ratios of 0.28 and 0.36 respectively were used for production settings such as a silica-to-rubber ratio of 20 phr and 25 phr.At these low flow rates, the acidic slurry was not sufficiently acidic to neutralize the ammonia in the latex. The acid-to-ammonia molar ratios for comparison examples 6-6 and 6-7 were 0.66 and 0.98, respectively. In both cases, only cloudy liquid was sprayed from the reaction zone. Using a higher slurry-to-latex flow rate would deliver sufficient acid from the slurry into the reaction zone to neutralize ammonia from the latex. Example 7 - Reference.

[0143] To investigate the process variables that enable the formation of a solid or semi-solid, silica-containing, continuous rubber phase, a series of experiments was conducted under various combinations of process parameters, including, but not limited to, the concentration of silica in the destabilized slurry, the concentration of acid or salts in the destabilized slurry, the latex types (e.g., field latex and latex concentrate), the concentration of ammonia in latex, the amount of latex, the flow rates of destabilized slurry and latex, the velocities of destabilized slurry and latex in the reaction zone, and the acid or salt concentrations in the reaction zone. This series of experiments was conducted according to Procedure A, and calcium nitrate was used as the salt.The solids contents of the fluids and the inlet nozzle velocities for the experiments are listed in Tables 7A and 7B, respectively, for a latex concentrate and field latex. At a low slurry-to-latex volumetric flow rate ratio (i.e., a low silica-to-rubber ratio in the reaction zone), the destabilized slurry and salt were diluted with the latex, and no solid or semi-solid, silica-containing, continuous rubber phase had formed. Subsequently, the silica-to-rubber ratio was gradually increased by increasing the slurry-to-latex volumetric flow rate ratio until the emergence of a solid or semi-solid, silica-containing, continuous rubber phase from the reaction zone was observed.In Tables 7A and 7B, “Silica loading introduced into the reaction zone” denotes the lowest silica-to-rubber ratio at which a solid or semi-solid, silica-containing, continuous rubber phase was formed. The minimum salt concentration in the reaction zone (including the destabilized slurry and latex) required to form a solid or semi-solid, silica-containing, continuous rubber phase was calculated for each set of experimental conditions (e.g., silica concentration in slurry, salt concentration in slurry, slurry rate). For the first six examples listed in Table 7A, the silica concentration in the destabilized slurry was identical, namely 18.5 wt.-%, but the salt concentration in the destabilized slurry was varied, and the lower threshold of silica loading for the formation of a solid or semi-solid, silica-containing, continuous rubber phase was determined by increasing the latex volumetric flow rate in each sample until coagulation was formed. The results in Table 7A show that when the salt concentration in the destabilized silica slurry was increased from 0.22 wt% to 0.75 wt%, it was possible to reduce the slurry-to-latex volumetric flow rate ratio to obtain a solid or semi-solid, silica-containing, continuous rubber phase with a lower silica-to-rubber ratio. For example, increasing the salt concentration from 0.22 wt% to 0.65 wt% of an 18.5 wt.With a silica slurry of -%, the minimum silica phr setting for providing a solid or semi-solid, silica-containing, continuous rubber phase decreased from 80 phr silica to 35 phr silica when the relative volumetric flow rate of the latex was increased and the ratio of slurry to latex volumetric flow rates was decreased from 1.17 to 0.51. Similar results were observed for other concentrations of silica slurry and when acid was used to destabilize the silica slurry.

[0144] Table 7a. Threshold values ​​for the formation of a solid or semi-solid, silica-containing, continuous rubber phase: phr silica loading and calcium nitrate concentration under various conditions when destabilized silica slurry was mixed with 50% diluted latex concentrate (31 wt% dry rubber content; 0.70 wt% ammonia content, except for the last sample where the ammonia content was 0.53 wt%) using method A. Table 7A Silica concentration in exfoliation (wt%) Ca(NO 3 ) 2 in addition (wt%) [Ca 2+ ]inAufschl.(mM) Zeta potential (estimated)(mV) Inlet nozzle speed (m / s) a Silica loading, introduced into reaction zone (phr) Ratio of flow rates to latex (v / v) [Ca 2+ [Conc. in reaction zone (mM)] 18,5 0,22 14,8 -22,0 87 80 1,17 7,9 18,5 0,39 26,2 -18,4 46 46,3 0,68 10,5 18,5 0,48 32,3 -17,0 67 40 0,59 11,9 18,5 0,52 34,9 -16,5 58 45 0,66 13,8 18,5 0,65 43,6 -15,1 58 35 0,51 14,7 18,5 0,75 50,4 -14,1 59 35 0,51 17,0 26 0,68 47,6 -14,5 54 55 0,55 16,8 26 0,99 69,3 -12,1 77 50 0,50 23,0 11 0,36 23,2 -19,1 80 35 0,90 10,9 20 1,00 67,8 -12,2 49 35 0,49 22,2 a. The inlet nozzle velocity is the velocity of the silica slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before contact with latex.

[0145] Table 7B. Threshold values ​​for the formation of a solid or semi-solid, silica-containing, continuous rubber phase: phr silica loading and calcium nitrate concentration under various conditions when the silica slurry was mixed with field latex using method A. Table 7B Silica concentration in exfoliation (wt%) Ca(NO 3 ) 2 in addition (wt%) [Ca 2+ ]inAufschl.(mM) Zeta potential opening (mV) Inlet nozzle speed (m / s) a Silica loading, lower limit (phr) Verh.Aufschl. zu Latex(v / v) [Ca 2+ [Conc. in reaction zone (mM)] 10 0,65 41,7 -15,4 78 65 1,96 27,6 19,6 0,90 60,8 -12,9 71 65 0,95 29,6 20 1,0 67,7 -12,2 76 65 0,93 32,6 20 1,3 88,0 -10,6 76 50 0,72 36,7 a. The inlet nozzle velocity is the velocity of the silica soot slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before contacting the latex.

[0146] In a batch-mode coagulation experiment carried out by mixing the silica slurry with latex in a bucket under relatively low shear, the minimum amount of salt or acid required to coagulate the latex in the mixture is a constant, regardless of the initial concentration of the salt or acid in the silica slurry prior to mixing. However, in processes according to various embodiments of the invention, the threshold concentration of the salt in the reaction zone for the formation of a solid or semi-solid, silica-containing, continuous rubber phase increases with increasing salt concentration in the destabilized silica slurry prior to mixing (i.e., the degree of destabilization of the silica slurry).For example, Table 7A shows that the threshold concentration of Ca(NO3)2 for coagulation of the latex concentrate is independent of the silica concentration in the destabilized slurry, but strongly dependent on the initial salt concentration in the destabilized silica slurry. When the salt concentration increased from 14.8 mM to 69.3 mM, the threshold salt concentration increased from 7.9 mM to 23.0 mM. For comparison, a series of batch coagulation experiments were carried out in a bucket under low-shear stirring, and it was determined that the threshold concentration of Ca(NO3)2 for coagulation of the same latex concentrate was constant at 10.7 mM, independent of both the initial salt concentration in the destabilized silica slurry and the silica concentration in the destabilized slurry.These results underscore the importance of matching the degree of silica slurry destabilization, the mixing rate, the rate of silica particle agglomeration, and the rate of latex coagulation under high shear to efficiently produce a solid or semi-solid, silica-containing, continuous rubber phase.

[0147] Similarly, the acid-ammonia threshold ratio for the formation of a solid or semi-solid, silica-containing, continuous rubber phase according to embodiments of the invention is not a constant, but increases with the degree of acid destabilization of the silica slurry.

[0148] Based on the production variables described herein, such as the velocity of the destabilized silica slurry, the velocity of the latex, the relative flow rates of the destabilized silica slurry and the latex fluids, the degree of destabilization of the silica slurry, the silica concentration in the destabilized slurry, the dry rubber content of the latex, and the ammonia concentration of the latex (e.g., the ammonia concentration can be reduced by bubbling nitrogen through the latex or on the surface of the liquid), it was possible to obtain or predict the formation of a solid or semi-solid, silica-containing continuous rubber phase over a range of desired silica loadings. Thus, the method of the invention can be operated over an optimized range of variables. Comparative example 8.

[0149] The following comparative experiments using a multi-stage batch process were carried out as a comparison to a continuous process according to embodiments of the invention.

[0150] In these comparative examples, a silica slurry was combined with elastomer latex under batch mixing conditions, using either a milled silica slurry (as in Procedure B above) or a silica slurry prepared without milling, each at two slurry concentrations: 25 wt% and 6 wt% (based on the total weight of the slurry). The silica used in these examples was ZEOSIL® 1165 MP. The elastomer latex used in all experiments was a highly concentrated ammonia latex concentrate (60CX12021 from Chemionics Corporation, Tallmadge, Ohio) diluted by 50% (by weight) with deionized water. Experiment 8-A: Mix batch with ground silicon dioxide slurry.

[0151] The silica slurry prepared above was mixed with a desired amount of deionized water in an 18.9 l (5 gallon) bucket to achieve the target silica concentration of the slurry.

[0152] For each run described below, the specified quantity of silica slurry was taken from the slurry run tank and mixed for fifteen minutes with the specified quantity of elastomer latex in an 18.9 L (5-gallon) bucket using an overhead low-shear stirrer (Model #1750, Arrow Engineering Co., Inc., Hillside, NJ). Except in Run 5, calcium chloride salt was added to the mixture, and mixing continued until coagulation appeared complete. Unless otherwise noted, the salt was added as a 20 wt% saline solution in deionized water. The amount of salt used (dry weight) is given below. The “target phr silica” reflects the amount of silica in phr expected to be present in the rubber composite based on the initial amount of silica used, assuming that all of the silica was incorporated into all of the rubber.Runs 1-4 were dewatered and dried according to procedure B described above.

[0153] Run 1 - Target 55 phr silica rubber composite using 25 wt% silica slurry.

[0154] Conditions (for approx. 1.9 kg of dried material): 2.7 kg 25 wt% silica slurry, ground 4.0 kg latex concentrate 0.060 kg (equivalent dry weight) salt in solution.

[0155] Observations: After coagulation was complete, large pieces of wet rubber composite formed around the mixing sheet. However, not all of the rubber and silica were incorporated into the coagulate during coagulation, as a milky liquid remained in the mixing container and a layer of wet silica settled at the bottom of the bucket. The dried coagulate weighed approximately 0.5 kg, which was much less than the target yield of 1.9 kg. A significant amount of silica appeared on the surface of the rubber product, indicating poor silica dispersion within the rubber composite. The silica appeared to be very poorly mixed with the rubber in the coagulate, and undispersed silica granules were felt and seen throughout the coagulate. Silica particles were observed to fall off the dried coagulate.When dry rubber was cut using scissors, silica particles fell off the cut surface. After drying, TGA analysis of the rubber showed that the average silica loading was approximately 44 phr.

[0156] Run 2 - Target 70 phr silica rubber composite using 25 wt% silica slurry.

[0157] Conditions (for approx. 1.9 kg of dried material): 3.1 kg 25 wt% silica slurry, ground 3.6 kg latex concentrate 0.060 kg of salt, added dry.

[0158] Observations: Large pieces of wet rubber formed around the mixing sheet, and the post-coagulation fluid was cloudy or milky. A silica layer remained at the bottom of the bucket. Approximately 1 kg of dried coagulate was produced. Similar to Run 1, very poor dispersion of silica particles within the rubber coagulate was observed. After drying, TGA analysis of the rubber product showed silica loadings averaging approximately 53 phr.

[0159] Run 3 - Target 55 phr silica rubber composite using 6 wt% silica slurry.

[0160] Conditions (for approx. 2 kg of dried material): 2.6 kg 25 wt% silica slurry, ground 8.4 kg deionized water 4.0 kg latex concentrate 0.090 kg of salt in solution.

[0161] Observations: After adding the salt, the entire mixture of latex and slurry cured into a soft gel. Approximately 0.9 kg of dry composite was produced. Similar to Run 1, very poor dispersion of silica particles within the rubber coagulate was observed. After drying, the silica loading in the coagulate, measured by TGA, was approximately 45 phr.

[0162] Run 4 - Target 70 phr silica rubber composite using 6 wt% silica slurry.

[0163] Conditions (for approx. 2 kg of dried material): 3.1 kg 25 wt% silica slurry, ground 9.9 kg of water 3.7 kg latex concentrate 0.10 kg of salt in solution.

[0164] Observations: After adding the salt, small granules formed in a milky liquid. A sieve was used to collect and compact the granules. Similar to Run 1, very poor dispersion of silica particles within the rubber coagulate was observed. Approximately 0.7 kg of dry composite was collected, with a silica loading in the crumb, measured by TGA, of about 50 phr.

[0165] Run 5 Target 55 phr silica-rubber composite using 25 wt% silica slurry, destabilized with 1% CaCl2

[0166] Conditions (for approx. 1.9 kg of dried material): 4.0 kg 25 wt% suspension containing 1% CaCl2, ground to 2.7 kg latex concentrate.

[0167] Observations: The latex was placed in a 5-gallon bucket using an overhead, low-shear stirrer. The milled 25% destabilized silica slurry, containing 1% CaCl₂, was poured into the bucket while stirring, and stirring continued until coagulation was complete. Visual and tactile observations of the rubber specimen revealed numerous large pockets (mm to cm in size) of silica slurry within the rubber specimen and a large amount of silica particles that were trapped but not dispersed within the solid rubber phase. The average silica loading in the dried coagulate, as measured by TGA, was approximately 58 phr. Sample-to-sample variations in silica loadings were greater than 10 phr.

[0168] Experiment 8-B: Batch mixing using a silica slurry without milling.

[0169] To prepare the silica slurry without milling, the silica was slowly added to water using only an overhead stirrer (Model #1750, Arrow Engineering Co., Inc., Hillside, NJ). When the silica appeared to be completely dispersed, the latex was added and the liquid mixture was stirred for 20 minutes. The CaCl₂ salt solution was then added to the liquid mixture and allowed to blend until coagulation appeared complete. The samples were dried in an oven prior to TGA analysis.

[0170] Run 5B - Target 65 phr silica rubber composite using 25 wt% silica slurry.

[0171] Conditions (for approx. 1.9 kg of dried material): 3.0 kg 25 wt% silica slurry 3.8 kg latex concentrate 0.06 kg of salt in solution.

[0172] Observations: After the addition of the salt, very large pieces of rubber coagulate formed around the stirrer blade. Following coagulation, a thick layer of silica settled at the bottom of the bucket. The rubber piece felt sandy and slimy. Silica grains could be felt and seen on the surface of the rubber coagulate, and visual observation revealed very poor silica distribution within the rubber coagulate. The silica loading in the coagulate was determined using TGA to be 25 phr.

[0173] Run 6 - Target 80 phr silica rubber composite using 25 wt% silica slurry.

[0174] Conditions (for approx. 1.9 kg of dried material): 3.3 kg 25 wt% silica slurry 3.4 kg latex concentrate 0.06 kg of salt in solution.

[0175] Observations: The silica loading in the rubber was determined to be 35 phr, and visual observation showed a very poor distribution of silica in the rubber coagulate.

[0176] Run 7 - Target 110 phr silica rubber composite using 6 wt% silica slurry.

[0177] Conditions (for approx. 1.9 kg of dried material, in two batches): 1.0 kg 25 wt% silica slurry 15.6 kg of water 3.0 kg latex concentrate 0.120 kg of salt in solution.

[0178] Observations: Small rubber granules formed in the bucket, and the liquid remaining after coagulation was mostly clear, with a silica layer at the bottom of the bucket. The silica loading in the rubber product, measured by TGA, averaged approximately 30 phr. The coagulate was elastic, with silica granules on the surface. When dried, silica could be easily brushed off the surface, and visual observation revealed very poor silica distribution within the rubber coagulate.

[0179] Run 8 - Target 140 phr silica rubber composite using 6 wt% silica slurry.

[0180] Conditions (for approx. 1.9 kg of dried material, in two batches): 1.0 kg 25 wt% silica slurry 15.7 kg of water 2.4 kg latex concentrate 0.110 kg of salt in solution.

[0181] Observations: Small rubber granules formed in the bucket, and the liquid residue after coagulation was mostly clear, with a silica layer at the bottom of the bucket. The silica loading in the rubber product, measured by TGA, averaged approximately 35 phr. Silica particles were deposited on the surface of the rubber product, which could be brushed clean upon drying, and visual observation revealed very poor silica distribution within the rubber coagulate.

[0182] Summary of observations. Compared with the continuous process for producing an elastomer composite, such as in Examples 5 and 7, the batch latex mixing process of Example 8 was unable to achieve the desired quality or quantity of silica dispersion in rubber. With milled silica slurries, the actual silica loading in rubber products produced by batch mixing was observed to be <55 phr. After coagulation, a significant amount of silica settled at the bottom of the mixing bucket and appeared on the surface of the rubber product, indicating poor trapping of silica particles within the rubber coagulate. With non-milled silica slurries, the actual silica loading in rubber produced by batch mixing was limited to 30 phr to 35 phr.After coagulation, a thick layer of silica settled at the bottom of the mixing bucket. The silica appeared to be very poorly mixed with the rubber in the coagulate, and undispersed silica granules were palpable and visible throughout the coagulate. Compared to processes according to embodiments of the present invention, batch mixing processes resulted in poor incorporation and distribution of silica particles within the rubber matrix of the coagulate. In the product of each of these batch mixing runs, silica particles were observed falling off dried coagulate. When a dry rubber composite was cut with scissors, silica particles fell off the cut surface. Such a loss of silica particles was not observed in the examination of the solid or semi-solid, silica-containing continuous rubber phase produced by processes according to embodiments of the invention.

[0183] Fig.Figure 3 graphically represents the mechanical properties of the samples of comparison example 1 (stars) and of the vulcanized silica elastomer composites of runs 1-4 of comparison example 8 (triangles) with respect to the silica loading (phr) ( Fig. 3A - Module ratio T300 / T100, Fig. 3B - Tensile strength (MPa), Fig. 3C - tan delta 60, and Fig. 3D - Elongation at break (%) * Tensile strength (MPa)). In each diagram are the samples of example 5, which satisfy the equations T300 / T100 ≥ -0.024s + 6.3 ( Fig. 3A), the tensile strength (MPa) ≥ -0.21s + 41 ( Fig. 3B), tan delta 60 ≤ 0.0022s - 0.05 ( Fig. 3C), or elongation at break (%) * tensile strength (MPa) ≥ -211s + 27543 ( Fig.3D), where s is the silica loading in phr, represented as diamonds. The diagrams show that the improved mechanical properties generally correlated with the use of a latex concentrate and / or a salt in a continuous wet masterbatch process, whether or not acid was used as an additional destabilizing agent. In contrast, the processes according to Comparative Example 8 were unable to produce a rubber of consistently high quality that met more than one of the criteria mentioned in the equations above.

[0184] Fig.Figure 4 graphically represents the modulus ratio (T300 / T100) of the samples from Comparative Example 1 (stars), the vulcanized elastomer composites from runs 1-4 of Comparative Example 8 (triangles), and the vulcanized elastomer composites of Example 5 (rhombuses) with respect to the tan Δδ 60 values. The diagram shows that only elastomer composites according to embodiments of the invention are capable of exhibiting both a high modulus of elasticity (greater than 5.5) and a low tan Δδ (less than 0.05) (Box 301). Since the modulus ratio generally decreases with increasing loading, more highly loaded silica elastomer composites may exhibit desirable properties without meeting these criteria.

[0185] Fig.Figure 5 graphically represents the modulus ratio (T300 / T100; diamonds) and tan Δ60 (squares) of the vulcanized elastomer composites from Example 5 with respect to the swelling index. The swelling index was measured by incubating a 0.5 g sample in toluene (sufficient to cover the sample) for 120 hours, changing the toluene after 48 hours. The sample is weighed to obtain a swelling weight, dried overnight at ambient temperature and pressure, and then dried again overnight in a vacuum oven at 50°C, after which the sample is weighed to obtain a dry weight. The swelling index is the difference between the swelling weight and the dry weight, divided by the dry weight. The graph shows that a source index in the range of about 1.80 to about 2.20, and especially from about 1.90 to about 2.10, is optimal to provide a high elastic modulus ratio of the vulcanized elastomer composite.Thus, the combination of mechanical properties of the vulcanized elastomer composite can be optimized by adjusting the swelling index, for example by adjusting the accelerator type. Example 9 - Reference

[0186] In these examples, the process for producing a silica-elastomer composite using the apparatus shown in Figure 1 (either (a) or (b)) was carried out under various operating conditions described in Table 8, employing either Process A or Process B as described above. The operating conditions were selected to obtain a silica-containing continuous rubber phase with the silica-to-rubber ratios specified in Table 8. In each example, the silica-containing continuous rubber phase comprised at least 40 wt% aqueous liquid. The approximate elongation at break of the silica-containing continuous rubber phase emerging from the reaction zone is also given in Table 8. Table 8 Example Procedure A / B Silica a Conc. in addition (wt.%) Latex type Rubber concentrate in latex (DRC) (wt%) Latex wt% NH 3 (wt.%) Salt type Salt wt.% in suspension (wt.%) Zeta potential (estimate) b (mV) 9-1 B 25 Concession 31 0,27 CaCl2 0,75 -11,4 9-2 B 25 Concession 31 0,27 CaCl2 0,75 -11,4 9-3 B 25 Concession 31 0,27 CaCl2 1,0 -9,5 9-4 B 25 Concession 31 0,27 N / A 0 -11,2 9-5 B 25 Concession 31 0,27 N / A 0 -11,2 9-6 B 25 Concession 31 0,27 N / A 0 -17,8 9-7 B 12,5 Concession 31 0,27 CaCl2 0,50 9-8 A 20 Concession 31,9 0,53 Ca(NO3)2 1,0 -12,2 9-9 A 20,0 Field- 32,7 0,33 N / A 0 -17,6 9-10 A 20,0 Field- 32,7 0,33 N / A 0 -17,6 9-11 A 20,0 Field- 32,7 0,33 Ca(NO3)2 1 -6,1 9-12 A 20,0 Field- 32,7 0,33 Ca(NO3)2 1 -6,1 9-13 A 20,0 Field- 32,7 0,33 Ca(NO3)2 1 -6,1 9-14 B 25 Concession 31,0 0,27 CaCl2 1,50 -6,9 9-15 B 25 Concession 31,0 0,27 CaCl2 1,00 -9,5 9-16 A 16,5 Concession 30,6 0,68 N / A 0,00 -16,5 9-17 B 25 Concession 30,5 0,27 Ca(NO3)2 0,59 -3,0 9-18 B 25 Concession 31 0,27 Ca(NO3)2 1,00 -12,1 Table 8 (continued) Example Acid type Acidity wt.% in slurry (wt.%) Acid / NH 3 mol. ratio Inlet nozzle speed . c (m / s) Actual silica loading (phr) Opening flow rate (L / hr) Latex flow rate d (L / hr) Flow rate ratio of extraneous to latex (v / v) Elongation at break of the solid rubber phase (%) 9-1 N / A 0 0,00 19 95 60 67 0,898 300-400 9-2 N / A 0 0,00 19 101 60 53 1,141 300-600 9-3 N / A 0 0,00 19 92 60 67 0,898 200-250 9-4 Ants 2,0 1,36 19 45 60 142 0,423 200-400 9-5 Ants 2,0 1,87 19 47 60 103 0,581 150-250 9-6 Vinegar- 2,6 1,35 19 61 60 142 0,423 200-300 9-7 Vinegar- 1,3 1,86 37 33 60 48 1,245 300-400 9-8 N / A 0 0,00 49 38,4 540 703 0,77 130 9-9 Vinegar- 2,8 3,14 75 54,8 945 826 1,14 130-150 9-10 Vinegar- 2,8 3,93 75 67,2 945 660 1,43 120 9-11 Vinegar- 2,8 1,77 76 54,9 963 841 1,14 120 9-12 Vinegar- 2,8 2,36 76 43,3 630 734 0,86 150 9-13 Vinegar- 2,8 1,77 76 34,0 630 978 0,64 150-200 9-14 N / A 0 0 19 138 60 43 1,38 300-400 9-15 N / A 0 0 19 122 60 37 1,63 300-500 9-16 Vinegar- 3,6 1,81 64 40,4 800 743 1,08 120-150 9-17 N / A 0 0 75 70,9 60 58 1,040 200-300 9-18 N / A 0 0 75 ND 60 142 0,422 130-150 N / A = not applicable ND = not determined a. In Example 9-17, Agilon 400 Silica (obtained from PPG Industries Inc.) was used. All other examples used ZEOSIL® Z1165 MP precipitated silica. b. Zeta potential values ​​were estimated by interpolation of experimentally determined curves of the zeta potential dependence on the concentration of the salt or acid of the suspensions of the same silica variety. c. The inlet nozzle velocity is the velocity of the silica slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before being brought into contact with the latex, d. The flow rates of the slurry and latex are the volume flow rates in L / h of the silica slurry or the latex fluid when they are supplied to the reaction zone.

[0187] The results show that highly elastic, silica-containing continuous rubber-phase materials in the form of solid objects can be obtained under a variety of operating conditions. Higher elongation correlates with the use of latex concentrate, lower production rates (dry-based material flow rate), increased residence time in the reaction zone, and / or lower flow rates of latex and / or destabilized silica slurry. Example 10 - Reference.

[0188] These examples describe manufacturing processes for elastomer composites according to various embodiments in the Fig.The apparatus shown in Figure 1(a) was prepared under various conditions, as described in Table 9, using Method A with field latex. In Example 10-4, a 10 wt% silica slurry was used; all other samples were prepared with a 20 wt% silica slurry. In all examples, Zeosil® Z1165 MP precipitated silica was used. The operating conditions were selected to obtain a solid or semi-solid, silica-containing, continuous rubber phase with the silica-to-rubber ratios specified in Table 9. The samples were dewatered according to Method A, followed by additional dewatering and drying according to Method B without the addition of coupling agents or antioxidants. Table 9 Example Number Rubber latex (DRC, wt%) NH3 in Latex (wt%). Salt wt.% in suspension. a Acidity wt.% in solution. b Acid / NH3 molar ratio Surcharge to MBRate(L / hr) c Latexzu MBRate(L / hr) c 1 32,7% 0,35% 1% 0 0,00 738 794 2 32,7% 0,35% 1% 0 0,00 738 688 3 32,7% 0,35% 1,3% 0 0,00 738 543 4 32,7% 0,35% 0,65% 0 0,00 950 484 5 32,7% 0,33% 0 2,80% 2,36 630 734 6 32,7% 0,33% 0 2,80% 3,14 945 826 7 32,7% 0,33% 0 2,80% 3,93 945 660 8 32,7% 0,33% 1% 2,80% 3,14 963 841 9 32,7% 0,33% 1% 2,80% 2,36 630 734 10 30,4% 0,37% 0 3,30% 2,69 738 791 a. All examples use calcium nitrate as a salt. b. All examples use acetic acid as the acid. c. Slurry and latex flow rates are the volume flows of the silica-soot slurry or the latex fluid upon arrival in the reaction zone in L / h. Table 9 (continued) Example Number Inlet nozzle speed (m / s) d Zeta potential (estimated) (mV) e Slurry to latex ratio (v / v) Actual SiO2 loading T300 / T100 1 76 -12,2 0,930 45,4 5,61 2 76 -12,2 1,073 52,3 5,13 3 76 -10,6 1,359 57,0 4,84 4 78 -15,4 1,963 52 5,68 5 76 -17,6 0,858 41,8 5,39 6 75 -17,6 1,145 54,8 5,53 7 75 -17,6 1,431 67,2 5,40 8 76 -6,1 1,145 54,9 5,13 9 76 -6,1 0,858 43,3 5,27 10 89 -16,8 0,933 44,1 5,12 d. The inlet nozzle velocity is the velocity of the silica slurry as it passes through a nozzle (3a) at the first inlet (3) to the reaction zone (13) before being brought into contact with the latex. e. Zeta potential values ​​were estimated by interpolation of experimentally determined curves of the zeta potential dependence on the concentration of the salt or acid of the suspensions of the same silica variety.

[0189] In all examples, the selected operating conditions resulted in a solid or semi-solid, silica-containing, continuous rubber phase in an approximately cylindrical shape. Upon manual compression, the semi-solid material remained coherent and expelled water while maintaining its solids content. The solid product contained a large amount of water, was elastic and compressible, and expelled water upon manual compression while maintaining its solids content. Silica particles were observed to be uniformly distributed throughout the continuous rubber phase, and this product was essentially free of free silica particles and larger silica grains on both the outer and inner surfaces. As in Fig.As shown in Figure 6, the application of a process in which a stream of destabilized silica slurry is combined with an elastomer latex results in an improvement in reinforcement compared to an elastomer composite produced by mixing dry silica and dry rubber (according to the stars in Figure 6). Fig. 6) was produced. The ones listed in Table 9 and in Fig. The 6 examples shown according to the invention (diamonds) all have module ratios (T300 / T100) that are equal to or greater than -0.025s + 6.2, where s is the silica loading.

[0190] The present invention may comprise any combination of the various features or embodiments above and / or below, as set forth in any sentences and / or paragraphs herein. Any combination of features disclosed herein shall be considered part of the present invention, and no limitation is intended with respect to combinable features.

[0191] In particular, the applicants refer to the entire content of all cited references in this disclosure. Furthermore, where a quantity, concentration, or other value or parameter is specified either as a range, preferred range, or a list of upper preferred values ​​and lower preferred values, this is to be understood as specifically disclosing all ranges formed by any pair of any upper range boundary or preferred value and any lower range boundary or preferred value, regardless of whether ranges are disclosed separately. Where a range of numerical values ​​is specified herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0192] It is intended that the present description and examples are to be regarded as merely exemplary, with the true scope of the invention being specified by the following claims.

Claims

[1] Vulcanizable elastomer composite comprising at least 40 phr silica dispersed in natural rubber, wherein, when the vulcanizable elastomer composite is vulcanized, the resulting vulcanizate has a T300 / T100 ratio of at least -0.024s + b, where s represents the amount of silica in the vulcanizable elastomer composite, expressed as parts per hundred weight rubber (phr) and b = 6.3, and the vulcanizable elastomer composite has the following additional properties: a) a tan ΔΔ60 of at most 0.0022 s - c, where c = 0.06; and b) a tensile strength in MPa of at least -0.21s + d, where d = 41; and if applicable c) Elongation at break (%) * tensile strength (MPa) of at least -211s + e, where e = 27543; and / or d) a silica content of at least 55 phr, for example at least 60 phr. [2] Vulcanizable elastomer composite according to claim 1, wherein the vulcanizate has a T300 / T100 ratio of at least -0.024s + b, where b = 6.

8. [3] Vulcanizable elastomer composite according to claim 1 or 2, wherein the vulcanizate has a tensile strength in MPa of at least -0.21s + d, where d = 41.

4. [4] Vulcanizable elastomer composite according to any one of claims 1 to 3, wherein the vulcanizate has a T300 / T100 ratio of at most 7. [5] Vulcanizable elastomer composite according to any one of claims 1 to 4, wherein the vulcanizable elastomer composite comprises up to 180 phr silica. [6] Vulcanizable elastomer composite according to any one of claims 1 to 5, wherein the vulcanizable elastomer composite comprises up to 10 wt% carbon black in relation to the total weight of the reinforcing particles in the vulcanizable elastomer composite. [7] Vulcanizable elastomer composite according to any one of claims 1 to 6, wherein the vulcanizate has a Tan Delta 60 of at least 0.

02. [8] Vulcanizable elastomer composite according to any one of claims 1 to 7, wherein the vulcanizate has a tensile strength of at most 40 MPa. [9] Vulcanizable elastomer composite according to any one of claims 1 to 8, wherein the vulcanizate has an elongation at break (%) * tensile strength (MPa) of not more than 21500. [10] Vulcanizable elastomer composite according to any one of claims 1 to 9, wherein the silica is precipitated silica with a surface area of ​​20 m² as measured by nitrogen adsorption 2 / g up to 450 m 2 / g include. [11] Vulcanizable elastomer composite according to any one of claims 1 to 10, wherein the vulcanizable elastomer composite comprises a dehydrated wet masterbatch of silica dispersed as a slurry in natural rubber latex. [12] Vulcanized elastomer composite comprising a vulcanizate of the vulcanizable elastomer composite according to any one of claims 1 to 11, optionally with a swelling index of 1.80 to 2.

20. [13] Vulcanizable elastomer composite comprising at least 40 phr silica dispersed in natural rubber, wherein, when the vulcanizable elastomer composite is vulcanized, the vulcanizate has a T300 / T100 ratio of at least -0.025s + 6.2 and a swelling index of 1.80 to 2.20, where s represents the amount of silica in the vulcanizable elastomer composite, expressed as parts per hundred weight of rubber (phr). [14] Vulcanizable elastomer composite according to claim 13, wherein the vulcanizable elastomer composite comprises a dehydrated wet masterbatch of silica dispersed as a slurry in field latex. [15] Vulcanizable elastomer composite according to claim 13 or 14, wherein the vulcanizable elastomer composite comprises at least 60 phr silica. [16] Vulcanizable elastomer composite according to any one of claims 13 to 15, wherein, when the vulcanizable elastomer composite is vulcanized, the vulcanizate has an elongation at break (%) * tensile strength (MPa) of at least -211s + e, where e = 27543 and s is the silica loading in phr. [17] Vulcanizable elastomer composite according to any one of claims 13 to 16, wherein the vulcanizate has a T300 / T100 ratio of at most 7. [18] Vulcanizable elastomer composite according to any one of claims 13 to 17, wherein the vulcanizable elastomer composite comprises up to 180 phr silica. [19] Vulcanizable elastomer composite according to any one of claims 13 to 18, wherein the vulcanizable elastomer composite comprises up to 10 wt% carbon black in relation to the total weight of the reinforcing particles in the vulcanizable elastomer composite. [20] Vulcanizable elastomer composite according to any one of claims 13 to 19, wherein the silica is precipitated silica with a surface area of ​​20 m² as measured by nitrogen adsorption 2 / g up to 450 m 2 / g includes. [21] Vulcanizable elastomer composite comprising silica dispersed in natural rubber, wherein, when the vulcanizable elastomer composite is vulcanized, the resulting vulcanizate has a T300 / T100 ratio of at least 5.5 and a Tan Delta 60 of at most 0.05 and a swelling index of 1.80 to 2.

20. [22] Vulcanizable elastomer composite according to claim 21, wherein the vulcanizable elastomer composite comprises at least 40 phr silica. [23] Vulcanizable elastomer composite according to claim 21 or 22, wherein the vulcanizate has a Tan Delta 60 of at least 0.

02. [24] Vulcanizable elastomer composite according to any one of claims 21 to 23, wherein the vulcanizate has a T 300 / T 100 ratio of at most 7. [25] Vulcanizable elastomer composite according to any one of claims 21 to 24, wherein the vulcanizable elastomer composite comprises at least 55 phr silica. [26] Vulcanizable elastomer composite according to any one of claims 21 to 25, wherein the vulcanizable elastomer composite comprises up to 10 wt.% carbon black in relation to the total weight of the reinforcing particles in the vulcanizable elastomer composite. [27] Vulcanizable elastomer composite according to any one of claims 21 to 26, wherein the silica is precipitated silica with a surface area of ​​20 m² as measured by nitrogen adsorption 2 / g up to 450 m 2 / g includes. [28] Vulcanizable elastomer composite according to any one of claims 21 to 27, wherein the vulcanizable elastomer composite comprises a dehydrated wet masterbatch of silica dispersed as a slurry in natural rubber latex. [29] Vulcanizable elastomer composite according to claim 14, wherein the field latex is de-sludged or chemically or enzymatically modified or contains added ammonia. [30] Vulcanizable elastomer composite according to any one of claims 1 to 9, 11, 13 to 19, 21 to 26 and 28, wherein the silica is precipitated silica.

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