Master batch production method

Abstract

The invention discloses a master batch production method. A method for producing a masterbatch includes continuously feeding a first composition comprising an elastomeric latex to a coagulation chamber; and continuously feeding a second composition containing a particulate filler and a salt to the coagulation chamber. The first composition and the second composition are mixed in a coagulation chamber to form a masterbatch. The salt may be provided such that the salt concentration in the coagulation chamber matches the salt concentration required to cause the magnitude of the zeta potential of the latex to be in the range of 30 to 15 mV, 15 to 1 mV, or 1 to 0 mV. The second composition may be fed to the coagulation chamber at a pressure of at least about 300 psig and / or at a speed of at least about 100 feet / second. The masterbatch may be dry-blended with an additional elastomer to form an elastomeric composite blend.

Description

Technical Field

[0001] The present invention relates to a method for producing a masterbatch, a method for producing an elastomeric composite blend and a masterbatch produced thereby. Background Art

[0002] The rate at which the elastomer particles coagulate in the elastomer latex is important.

[0003] It would be desirable to develop new masterbatch production methods that have more control over the coagulation rate of such particles. Summary of the invention

[0004] In some embodiments, a method for producing a masterbatch is disclosed. The method includes continuously feeding a first composition containing an elastomer latex to a coagulation chamber; and continuously feeding a second composition containing a particulate filler and a salt to a coagulation chamber. The first composition and the second composition are mixed in a coagulation chamber to form a masterbatch. In some embodiments, the particulate filler includes carbon black. The elastomer latex may include natural rubber. In some embodiments, the second composition is fed to the coagulation chamber at a pressure of at least 300 psig (e.g., about 500 to about 5,000 psig). The second composition can be fed to the coagulation chamber at a speed of at least about 100 feet per second (e.g., about 100 feet per second to about 800 feet per second). A certain amount of salt in the second composition can be fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the zeta potential of the latex in the range of 30 to 15, in the range of 15 to 1, or in the range of 1 to 0.

[0005] In other embodiments, a method for producing an elastomer composite blend is disclosed. The method includes continuously feeding a first composition containing an elastomer latex into a coagulation chamber; and continuously feeding a second composition containing a particulate filler and a salt into a coagulation chamber, wherein the first composition and the second composition are mixed in the coagulation chamber to form a masterbatch; and the masterbatch is dry-mixed with an additional elastomer to form an elastomer composite blend. In some embodiments, the additional elastomer includes at least one material selected from the following: natural rubber, chlorinated natural rubber, the following homopolymers, copolymers or terpolymers: 1,3-butadiene, styrene, isoprene, isobutylene, 2,3-dimethyl-1,3-butadiene, acrylonitrile, ethylene and propylene. The particulate filler may include carbon black. In some embodiments, the elastomer latex includes natural rubber. The second composition may be under a pressure of at least 300 psig; and / or fed to the coagulation chamber at a speed of at least about 100 feet per second. In some embodiments, an amount of salt in the second composition is fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 30 to 15, in the range of 15 to 1, or in the range of 1 to 0.

[0006] In a further embodiment, a masterbatch produced by the following method is disclosed, the method comprising continuously feeding a first composition containing an elastomer latex into a coagulation chamber; and continuously feeding a second composition containing a particulate filler and a salt into the coagulation chamber at a speed of at least about 100 feet per second. The first composition and the second composition are mixed in the coagulation chamber to form a masterbatch. In some embodiments, a certain amount of the salt in the second composition is fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the zeta potential of the latex in the range of 30 to 0 (e.g., 30 to 15, 15 to 1, or 1 to 0).

[0007] In other embodiments, a method for producing a masterbatch is disclosed, the method comprising mixing an elastomer latex, a particulate filler, and a salt in a coagulation chamber. The elastomer latex can be provided in a first composition, and the filler and the salt can be provided in a second composition. In some embodiments, the latex, the filler, and the salt are provided in different streams. The latex and the salt can be provided in the same stream.

[0008] The present invention discloses the following embodiments:

[0009] 1. A method for producing a masterbatch, comprising:

[0010] The elastomer latex, particulate filler and salt are mixed in a coagulation chamber.

[0011] 2. The method of embodiment 1, wherein the particulate filler comprises carbon black.

[0012] 3. The method of embodiment 1, wherein the elastomer latex comprises natural rubber.

[0013] 4. The method of embodiment 1 further comprises:

[0014] continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and

[0015] A second composition comprising particulate filler and salt is continuously fed to the coagulation chamber.

[0016] 5. The method of embodiment 4, wherein the second composition is fed to the coagulation chamber at a pressure of at least 300 psig; and / or wherein the second composition is fed to the coagulation chamber at a velocity of at least about 100 feet per second.

[0017] 6. The method of embodiment 1, wherein the elastomer latex, the filler and the salt are provided to the coagulation reactor in separate streams.

[0018] 7. The process of embodiment 1, wherein the elastomer latex and the salt are provided to the coagulation reactor in the same stream.

[0019] 8. The method of embodiment 1, wherein an amount of salt is provided so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 30 to 15.

[0020] 9. The method of embodiment 1, wherein an amount of salt is provided so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 15 to 1.

[0021] 10. The method of embodiment 1, wherein an amount of salt is provided such that the salt concentration in the coagulation chamber matches the salt concentration required to bring the magnitude of the zeta potential of the latex to a range of 1 to 0.

[0022] 11. A method for producing an elastomeric composite blend, comprising:

[0023] continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and

[0024] continuously feeding a second composition comprising a particulate filler and a salt into a coagulation chamber, wherein the first composition and the second composition are mixed in the coagulation chamber to form a masterbatch; and

[0025] The masterbatch is dry blended with additional elastomer to form an elastomeric composite blend.

[0026] 12. The method of embodiment 11, wherein the additional elastomer comprises at least one material selected from the group consisting of natural rubber, chlorinated natural rubber, homopolymers, copolymers or terpolymers of 1,3-butadiene, styrene, isoprene, isobutylene, 2,3-dimethyl-1,3-butadiene, acrylonitrile, ethylene and propylene.

[0027] 13. The method of embodiment 11, wherein the particulate filler comprises carbon black.

[0028] 14. The method of embodiment 11, wherein the elastomer latex comprises natural rubber.

[0029] 15. The method of embodiment 11, wherein the second composition is fed to the coagulation chamber at a pressure of at least 300 psig; and / or wherein the second composition is fed to the coagulation chamber at a velocity of at least about 100 feet per second.

[0030] 16. The method of embodiment 11, wherein an amount of salt in the second composition is fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 30 to 15.

[0031] 17. The method of embodiment 11, wherein an amount of salt in the second composition is fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 15 to 1.

[0032] 18. The method of embodiment 11, wherein an amount of salt in the second composition is fed so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 1 to 0.

[0033] 19. A masterbatch produced by a process comprising:

[0034] continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and

[0035] continuously feeding a second composition comprising a particulate filler and a salt into a coagulation chamber at a velocity of at least about 100 feet per second;

[0036] The first composition and the second composition are mixed in a coagulation chamber to form a masterbatch.

[0037] 20. The masterbatch of embodiment 19, wherein an amount of salt in the second composition is fed such that the salt concentration in the coagulation chamber matches the salt concentration required to give a zeta potential of the latex in the range of 30 to 0.

[0038] These and other non-limiting aspects and / or objects of the present disclosure are more particularly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The following is a brief description of the drawings, which are presented to illustrate exemplary embodiments disclosed herein and not to limit the same.

[0040] Figure 1 is a schematic flow diagram of a system and method for preparing an elastomer masterbatch according to some embodiments of the present disclosure.

[0041] Figure 2 is with Figure 1 Schematic flow of Figure 1 A partial schematic front view of a consistent implementation scheme.

[0042] Figure 3 is with Figure 1 Schematic flow of Figure 1 A partial schematic elevation view of an alternative embodiment of the present invention.

[0043] Figure 4 yes Figure 3 A partial cross-sectional elevation view of a mixing head / coagulation reactor assembly of an embodiment of .

[0044] Figure 5 is corresponding to Figure 4 A partial cross-sectional elevation view of a view showing an alternative embodiment.

[0045] Figure 6 is along Figure 5 A cross-sectional view taken along line 6-6.

[0046] Figure 7 is a cross-sectional view of a mixing head suitable for use in an alternative embodiment. Specific implementation plan

[0047] The present disclosure may be understood more readily by reference to the following detailed description and accompanying drawings of desirable embodiments included in the disclosure.In the following specification and in the claims that follow, reference will be made to a number of terms which shall be defined to have the following meanings.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art. In the event of a conflict, this document (including definitions) shall prevail. Methods and materials are described below, although similar or equivalent methods and materials may be used in the practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated herein in their entirety by reference. The materials, methods and products disclosed herein are exemplary only and are not intended to be limiting.

[0049] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0050] The term "comprising" as used in the specification and claims may include the embodiments of "consisting of" and "consisting essentially of." As used herein, the terms "comprising," "including," "having," "having," "may," "containing," and variations thereof are intended to be open transition phrases that require the presence of specified ingredients / steps and allow for the presence of other ingredients / steps. However, such descriptions should be interpreted as also describing compositions, mixtures, or methods as "consisting of" and "consisting essentially of" the listed ingredients / steps, which only allow for the presence of the specified ingredients / steps, and any impurities that may result therefrom, and exclude other ingredients / steps.

[0051] Unless otherwise indicated, the numerical values ​​in the specification should be understood to include the same value when reduced to the same number of significant figures and values ​​that differ from the specified value by less than the experimental error of ordinary measurement techniques used to determine the particular value.

[0052] All ranges disclosed herein are inclusive of the recited endpoints and are independently combinable (e.g., the range "2 to 10" includes the endpoints 2 and 10 and all intermediate values). The endpoints of the ranges and any values ​​disclosed herein are not limited to the exact ranges or values; they are imprecise enough to include values ​​approximating these ranges and / or values.

[0053] As used herein, approximations can be used to modify any quantitative representation that may vary without causing a change in the basic function to which it relates. Therefore, the value modified by one or more terms such as "approximately" and "substantially" may not be limited to the specified exact value in some cases. The modifier "approximately" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the phrase "about 2 to about 4" also discloses a range of "2 to 4". The term "approximately" may refer to plus or minus 10% of the value shown. For example, "about 10%" may refer to a range of 9% to 11%, and "about 1" may refer to 0.9-1.1.

[0054] For the enumeration of numerical ranges herein, each intermediate number with the same precision is expressly contemplated. For example, for the range of 6-9, in addition to 6 and 9, the numbers 7 and 8 are also contemplated, and for the range of 6.0-7.0, the numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9 and 7.0 are expressly contemplated.

[0055] The present disclosure relates to a masterbatch prepared by mixing an elastomer latex (e.g., a latex containing natural rubber) with a slurry containing filler particles (e.g., carbon black particles) and a salt. The slurry and latex are provided to a coagulation chamber, and the slurry can be provided at a much higher speed than the latex to promote high-speed collisions between the filler particles and the rubber particles. The inclusion of salt increases the effective ion concentration during turbulent mixing, which destabilizes the electrostatic repulsion of the charged latex particles and promotes coagulation. This may be particularly advantageous when working with well-stable latexes such as centrifuged and ammoniated natural rubber latexes (which may be more difficult to coagulate only via mechanical instability).

[0056] The latex may be a water-based latex.

[0057] Non-limiting examples of suitable latexes include latex-styrene butadiene rubber (ESBR), isoprene rubber, butyl rubber, nitrile rubber (NBR), chloroprene rubber, and natural rubber. Non-limiting examples of natural rubbers include Hevea, Guayule, TKS (Taraxacum), milkweed, sunflower, and other naturally derived latexes.

[0058] The salt may be a water-soluble salt.

[0059] In some embodiments, the term "soluble salt" refers to a salt that can be dissolved in an amount of at least 20 grams of salt per liter of solvent.

[0060] In some embodiments, the salt is selected to preferably raise the pH of the aqueous phase minimally (neutral salts), since typical latexes are stable at alkaline pH.

[0061] Carbonates, bicarbonates, and phosphates may be used. However, in some embodiments, these materials are not preferred because they raise the pH.

[0062] In a preferred embodiment, the salt lowers the pH. Examples include ammonium cations, calcium cations, and magnesium cations.

[0063] In some embodiments, the salt introduces divalency into the system. For example, the salt can introduce calcium, magnesium, or aluminum cations and sulfate, phosphate, or anions.

[0064] In some embodiments, the salt is selected from fluoride, chloride, bromide, sulfate, and nitrate.

[0065] The molar concentration of the salt can be increased until the zeta potential of the latex is 30-15 mV, 15-1 mV, or 1-0 mV.

[0066] The zeta potential can be determined at a pH similar to that of the original latex. For example, for ammoniated natural rubber latex, the zeta potential measurement can be performed at pH 10, a temperature of 298 K, and a water dielectric constant of 80. The electrophoretic mobility of the particles can be measured, for example, by a Malvern Zetasizer Nano ZS and related to the zeta potential via the Henry equation: Among them U E is the electrophoretic mobility, z is the zeta potential, ε is the dielectric constant (assumed to be 80 for water), η is the viscosity, f(ka) is the Henry function (assumed to be 1.5 via the Smoluchowski approximation due to the polar nature of the water solvent), k is the Debye length, and a is the particle radius.

[0067] The amount of salt added can be determined by:

[0068] 1. Identify the type of latex to be coagulated, including its pH;

[0069] 2. Zeta potential measurement of the latex at this pH with zero added salt;

[0070] 3. Repeating the zeta potential measurement of the latex at this pH, but adding some salt each time, until the desired salt concentration is determined, e.g., a zeta potential in the range of 30-15 mV, 15-1 mV, or 0-1 mV; and

[0071] 4. Use the preferred salt concentration to determine how much salt to add to the CB stream, fresh stream, or latex stream so that when all materials are collected in the coagulation chamber, the salt concentration will be equal to the concentration determined in step 3.

[0072] For an ammoniated NR latex having an initial molar concentration of monovalent ions of 0.05 M (~-65 mV ζ potential) at pH 10, salt can be added to the CB stream so that the concentration of the mixture in the mixing chamber is 0.20 M (~-30 mV ζ potential), increased to 3 M (~0 mV ζ potential) to maximize coagulation.

[0073] For example, zeta potential can be measured using a ZetaPlus instrument or a Malvern Autosizer 4700 from Brookhaven Instruments Corporation.

[0074] By increasing the ion concentration in the mixing chamber, the coagulation efficiency defined by the % coagulated of the initial latex charge in the mixing chamber can be improved from unacceptable levels (e.g., <99% coagulation efficiency) to acceptable levels (e.g., greater than or equal to 99% coagulation efficiency).

[0075] As measured by nephelometric turbidity units (NTU), the turbidity of the product wastewater can be significantly reduced, for example, by an order of magnitude. In some embodiments, the turbidity is reduced from a range of about 100 to about 500 NTU to a range of about 5 to about 50 NTU.

[0076] Additional salt may be added via one or more of the filler-containing stream, the latex-containing stream, and / or in an additional stream.

[0077] Based on the guidance provided herein, one of ordinary skill in the art is able to maximize latex destabilization without introducing pre-coagulation prior to the mixing nozzle.

[0078] The preferred range may not be how much it drives the system to coagulate. Rather, the form of the material produced may be critical. Higher salt concentrations (lower zeta potential magnitude) will produce smaller masterbatch coagulations. One of ordinary skill in the art will understand how to balance coagulation rate / efficiency with the dehydration efficiency of their system.

[0079] Salts can be selected based on the operating system to minimize long term corrosion. For example, in a stainless steel system, sulfates or phosphates may be preferred over chlorides.

[0080] With the methods and apparatus disclosed herein, an elastomeric composite blend can be produced comprising (i) an elastomeric masterbatch produced in a continuous flow process involving a mixture of an elastomeric latex and a particulate filler fluid under turbulence levels and flow control conditions sufficient to achieve coagulation even without the use of conventional coagulants, and (ii) an additional elastomer added to such elastomeric masterbatch in a dry blending step. Some optional aspects are disclosed in U.S. Pat. No. 6,075,084 to Mabry et al., which is incorporated herein by reference in its entirety.

[0081] In the example of an elastomer composite blend comprising natural rubber, butadiene rubber (in this discussion, in some cases, referred to as "BR") and a carbon black filler, it can be seen that the method of producing an elastomer composite blend advantageously provides flexibility, allowing better control of the distribution of fillers between two different elastomer phases within the elastomer composite blend. For some applications, it is beneficial that the carbon black filler is mainly in the natural rubber phase of the elastomer composite blend. According to existing known dry methods / dry mixing techniques, carbon black can be mixed with natural rubber using dry mixing techniques, and then BR is added and further dry mixed. Disadvantageously, a large portion of the carbon black will migrate into the BR phase, due to its affinity for the BR phase and the less desirable macroscopic dispersion of carbon black in the natural rubber phase. In contrast, the improved performance properties of comparable elastomer composite blends prepared by the wet mixing / dry mixing method disclosed herein show that when carbon black is mixed with natural rubber in the initial wet mixing step and then BR is added in the subsequent dry mixing step, more carbon black is retained in the natural rubber phase.

[0082] According to the wet mixing step of the method disclosed herein, the feed rate of the latex fluid and the particle filler fluid to the mixing zone of the coagulum reactor can be accurately metered to achieve high yields, with almost no free latex and almost no undispersed filler in the product crumb at the discharge end of the coagulum reactor. Without wishing to be bound by theory, it is currently understood that a quasi-single-phase system is established in the mixing zone, except where coagulated solids are formed and or downstream in the coagulum zone. It is believed that the extremely high feed rate of the particle filler fluid into the mixing zone of the coagulum reactor and the speed difference relative to the latex fluid feed are significant in achieving sufficient turbulence, that is, the energy of the latex is sufficiently large to achieve shearing by the impact of the particle filler fluid jet so that the particles are completely mixed and dispersed into the latex fluid and coagulated. The high mixing energy produces a product masterbatch crumb with excellent dispersion and controlled product delivery. A coagulum is generated, and then a desirable extrudate is formed. The particulate filler fluid and the elastomer latex can be fed continuously, meaning that a continuous flow of the coagulation masterbatch is established from the mixing zone to the discharge end of the coagulation reactor while maintaining an uninterrupted flow of the feed fluid. Typically, the uninterrupted flow of the feed fluid and the simultaneous discharge of the coagulation masterbatch are maintained for one or more hours, such as more than 24 hours, and perhaps even a week or longer.

[0083] Although various embodiments may use a variety of different fillers and elastomers, in some cases, for convenience, certain portions of the following detailed description of the methods and apparatus aspects of the present disclosure will describe a masterbatch comprising natural rubber and carbon black. Thanks to the present disclosure, it will be within the capabilities of those skilled in the art to employ the methods and apparatus disclosed herein to produce masterbatches and elastomer composite blends comprising a number of alternative or additional elastomers, fillers, and other materials in accordance with the principles of operation discussed herein. In short, the method for preparing an elastomer masterbatch involves simultaneously feeding (a) a slurry of carbon black or other filler with a salt; and (b) a natural rubber latex fluid or other suitable elastomer fluid into a mixing zone of a coagulation reactor. The coagulation zone extends from the mixing zone and may have a cross-sectional area that gradually increases in a downstream direction from the inlet end to the discharge end. The slurry may be fed to the mixing zone as a continuous high-speed jet of an injection fluid, while the natural rubber latex fluid is fed at a relatively low rate. The high velocity, flow rate and particle concentration of the filler slurry are sufficient to cause mixing and high shear of the latex fluid, flow turbulence of the mixture in at least the upstream portion of the coagulation zone, and substantially complete coagulation of the elastomer latex before the discharge end. Substantially complete coagulation can thereby be achieved. The continuous flow method for producing an elastomer composite material comprises continuously and simultaneously feeding the latex fluid and the filler slurry into the mixing zone of a coagulation reactor, establishing a continuous, semi-confined flow of the mixture of the latex and the filler slurry in the coagulation zone. The elastomer composite material debris in the form of "wonns" or pellets is discharged from the discharge end of the coagulation reactor in a substantially constant flow, while the latex and carbon black slurry streams are continuously fed into the mixing zone of the coagulation reactor. It is noteworthy that the piston-type flow and atmospheric or near-atmospheric conditions at the discharge end of the coagulation reactor are highly advantageous in facilitating the control and collection of the elastomer composite product, such as for immediate or subsequent further processing steps. The feed rate of natural rubber latex fluid and carbon black slurry to the mixing zone of coagulation reactor can be accurately metered to achieve high yield, and there is almost no free latex and almost no undispersed carbon black in the product crumbs at the discharge end of the coagulation reactor. Without wishing to be bound by theory, it is currently understood that a quasi-single-phase system is established in the mixing zone, except where a coagulated solid is formed and / or its downstream in the coagulation zone. It is believed that the extremely high feed rate of the carbon black slurry into the mixing zone of the coagulation reactor and the speed difference relative to the natural rubber latex fluid feed are significant in achieving sufficient turbulence, that is, the latex is subjected to a sufficiently large shearing of energy by the impact of the particle filler fluid jet, so that the particles are fully mixed and dispersed in the latex fluid and coagulated. High mixing energy produces a novel product with excellent macroscopic dispersion and controlled product delivery. A coagulum is generated, and a desirable extrudate is subsequently formed.

[0084] The masterbatch prepared by the above-mentioned wet mixing techniques and equipment can be formed into an elastomeric composite blend by subsequent dry mixing with an additional elastomer. Thus, in some embodiments, the present disclosure relates to a wet / dry method. The dry mixing step of the wet / dry mixing method can be carried out with commercially available equipment and techniques, including, for example, a Banbury mixer, etc. The additional elastomer added during the dry mixing step of the wet / dry mixing method disclosed herein can be one or more elastomers that are the same or different from the one or more elastomers used to form the masterbatch. During the dry mixing step, other ingredients may also be added together with the additional elastomer, including, for example, filler oils, additional particulate fillers, curing agents, etc., in which additional particulate fillers are added during the dry mixing step. In those embodiments, such additional fillers may be the same or different from the one or more fillers used in the masterbatch formed by the wet mixing step.

[0085] The above-mentioned apparatus and technique for producing the elastomeric composite blend disclosed herein are discussed in conjunction with the accompanying drawings, wherein the continuous flow wet mixing step for producing the elastomeric masterbatch adopts a continuous semi-confined flow of an elastomeric latex, such as natural rubber latex (fresh latex or concentrate), mixed with a filler slurry with salt (e.g., an aqueous slurry of carbon black with calcium chloride) in a coagulation latex reactor (which extends from the inlet end to the discharge end with a gradually increasing cross-sectional area) forming an elongated coagulation zone. The term "semi-confined" flow refers to a highly advantageous feature. As used herein, the term is intended to mean that the flow path followed by the latex fluid and filler slurry mixed in the coagulation reactor is closed or substantially closed upstream of the mixing zone and is open at the opposite downstream end of the coagulation reactor (i.e., at the discharge end of the coagulation reactor). Turbulent flow conditions in the upstream portion of the coagulation zone are maintained in a continuous at least quasi-steady state manner, while maintaining basic piston flow conditions at the open discharge end of the coagulation reactor. The discharge end is "open" at least in the sense of allowing the coagulant to discharge, usually at or near atmospheric pressure and usually by simple gravity descent (optionally in a shielded or screened flow path) into a suitable collection device (such as the feed hopper of a dewatering extruder). Thus, the semi-confined flow leads to a turbulence gradient that extends axially or longitudinally within at least a portion of the coagulation reactor. Without wishing to be bound by theory, it is currently understood that the coagulation zone is of great significance in allowing high turbulence mixing and coagulation in the upstream part of the coagulation reactor in combination with the essentially piston-type discharge flow of the solid product at the discharge end. The carbon black or other filler slurry is injected into the mixing zone in the form of a continuous jet while being carried out in a continuous manner, and the elastomer masterbatch debris discharged under essentially piston-type flow conditions and usually ambient pressure is easily collected at the discharge end of the coagulation reactor. Similarly, the axial velocity of the slurry entering the mixing zone through the slurry nozzle and usually at the upstream end of the coagulation zone is much higher than the axial velocity at the discharge end. According to the embodiments discussed below, when the slurry enters the mixing zone from a small bore, axially oriented feed pipe, the axial velocity of the slurry will typically be several hundred feet per second. In a typical application, at the feed end of the coagulation reactor with an expanded cross-sectional area, the axial velocity of the resulting stream may be, for example, 5 to 20 feet per second, and more typically 7 to 15 feet per second. At the discharge end, again in contrast, the axial velocity of the masterbatch crumb product discharged there will be about 1 to 10 feet per second, and more typically 2 to 5 feet per second in a typical application. Thus, the aforementioned semi-confined turbulence achieves the following very significant advantages: by mixing with carbon black or other fillers, natural rubber or other elastomer latex is coagulated, and a controlled, possibly quasi-molded product is delivered by the coagulation reactor for subsequent processing, even without subsequent treatment in a stream or tank of an acid, salt or other coagulant solution.

[0086] In this regard, it should be understood that referring to the coagulation reactor as "open" at the discharge end is not intended to mean that the discharge end must be exposed to sight or easily accessible by hand. Instead, it may be permanently or releasably attached to a collection device or subsequent processing device, such as a splitter (discussed further below), a dryer, etc. The discharge end of the coagulation reactor is open, and it is important to allow turbulence within the coagulation zone of the coagulation reactor (under high pressure and sealed to prevent any significant backward (i.e. upstream) travel at the mixing zone) to establish the aforementioned pressure and / or velocity gradient as it travels toward and away from the discharge end.

[0087] It should also be recognized in this regard that the turbulence of the flow is reduced along the coagulation reactor toward the discharge end. The basic piston flow of the solid product is achieved before the discharge end, depending on factors such as the percentage of capacity utilization, the choice of materials, etc. The flow mentioned here as a piston flow at or before the discharge end of the coagulation reactor should be understood based on the fact that the flow at the discharge end is mainly or completely composed of masterbatch debris, that is, small balls or "worms" of the coagulated elastomer masterbatch. At the point along the coagulation zone where the flow becomes a basic piston flow, the debris is usually quasi-molded into the internal shape of the coagulation zone. The continuously advancing mass of "worms" or small balls advantageously has a piston-type flow, which means that they usually or mainly travel axially toward the discharge end, and have a fairly uniform speed at any time point in a given cross-section of the coagulation zone near the discharge end, so that they are easy to be collected and controlled for further processing. Thus, the fluid phase mixing aspect disclosed herein can be advantageously carried out under steady-state or quasi-steady-state conditions, thereby producing a high level of product uniformity.

[0088] exist Figure 1 A non-limiting embodiment of the wet mixing step of the method and apparatus disclosed herein is schematically illustrated in FIG. Those skilled in the art will recognize that various aspects of system configuration, component selection, etc. depend to some extent on the specific characteristics of the intended application. Thus, for example, factors such as maximum system throughput and flexibility in material selection will affect the size and layout of system components. In general, such considerations will be well within the capabilities of those skilled in the art in light of this disclosure. Figure 1The system shown in the figure includes a device for feeding natural rubber latex or other elastomer latex fluid continuously to the mixing zone of the coagulation reactor at low pressure and low speed, in particular, a latex pressure tank 10 is shown to keep the feed supply of latex under pressure. Alternatively, a latex storage tank can be used, which is equipped with a peristaltic pump or a series of pumps or other suitable feeding devices, and the feeding device is suitable for keeping the elastomer latex fluid fed to the mixing zone of the coagulation reactor 14 via a feed line 12. The latex fluid in the tank 10 can be kept under air or nitrogen pressure, etc., so that the latex fluid is fed to the mixing zone under a pipeline pressure (e.g., less than 10psig, about 2 to about 8psig, or about 5psig). The flow lines, connections, etc. of the latex feed pressure and the latex feed device should be arranged to make the shear in the flowing latex fluid as low as possible. In some embodiments, all flow lines are smooth, with only large radius turns (if any), and smooth or streamlined interconnections between pipelines. Select pressure to produce the required flow rate entering the mixing zone. A non-limiting example of a useful flow rate is no more than about 12 feet per second.

[0089] Suitable elastomer latex fluids include both natural and synthetic elastomer latexes and latex blends. The latex must be suitable for coagulation by the selected particulate filler and must be suitable for the intended purpose or application of the final rubber product. With the benefit of this disclosure, it will be within the capabilities of those skilled in the art to select an elastomer latex or a suitable elastomer latex blend suitable for the methods and apparatus disclosed herein. Exemplary elastomers include, but are not limited to, rubber, the following polymers (e.g., homopolymers, copolymers and / or terpolymers): 1,3-butadiene, styrene, isoprene, isobutylene, 2,3-dimethyl-1,3-butadiene, acrylonitrile, ethylene and propylene, etc. The elastomer may have a glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) of about -120°C to about 0°C. Examples include, but are not limited to, styrene-butadiene rubber (SBR), natural rubber and its derivatives such as chlorinated rubber, polybutadiene, polyisoprene, poly(styrene-co-butadiene) and oil-extended derivatives of any of them. Blends of any of the foregoing may also be used. The latex may be in an aqueous carrier liquid. Alternatively, the liquid carrier may be a hydrocarbon solvent. In any case, the elastomeric latex fluid must be suitable for controlled continuous feeding into the mixing zone at an appropriate rate, pressure, and concentration. Non-limiting examples of suitable synthetic rubbers include copolymers of about 10 to about 70 weight percent styrene and about 90 to about 30 weight percent butadiene, such as copolymers of 19 parts styrene and 81 parts butadiene, copolymers of 30 parts styrene and 70 parts butadiene, copolymers of 43 parts styrene and 57 parts butadiene, and copolymers 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 monomers containing olefinic groups copolymerizable therewith, such as styrene, methylstyrene, chlorostyrene, acrylonitrile, 2-vinyl-pyridine, 5-methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine, 2-methyl-5-vinylpyridine, alkyl-substituted acrylates, vinyl ketones, methylisopropenyl ketone, methyl vinyl ether, α-methylene carboxylic acids and their esters and amides such as acrylic acid and dialkylacrylic acid amides. Also suitable for use herein are copolymers of ethylene and other high alpha olefins such as propylene, butene-1 and pentene-1.

[0090] The additional elastomer added during the dry mixing step of the wet / dry mixing method can use any elastomer or elastomer mixture suitable for the intended use or application, including those listed for the wet mixing step above. According to some embodiments, the elastomer latex used in the wet mixing step is natural rubber latex, and the additional elastomer used in the dry mixing step is butadiene rubber (BR). In such embodiments, butadiene rubber can form a secondary phase or composition of an elastomer composite blend, such as 10 weight % to 50 weight % of total elastomer in the elastomer composite blend. According to some other embodiments, the elastomer latex used in the wet mixing step is natural rubber latex, and the additional elastomer used in the dry mixing step is styrene-butadiene rubber (SBR). In some embodiments, SBR can form a primary phase or composition of an elastomer composite blend, such as 50 weight % to 90 weight % of total elastomer in the elastomer composite blend. According to some other embodiments, the additional elastomer is natural rubber. According to some other embodiments, the elastomer latex used in the wet mixing step is butadiene rubber latex, and the additional elastomer used in the dry mixing step is SBR. In such embodiments, SBR can be 10 weight % to 90 weight % of total elastomer in the elastomer composite blend. According to some other embodiments, the elastomer latex used in the wet mixing step is butadiene rubber latex, and the additional elastomer used in the dry mixing step is natural rubber. In such embodiments, natural rubber can be the minor component or phase of the elastomer composite blend, such as 10 weight % to 50 weight % of total elastomer in the elastomer composite blend. According to some other embodiments using butadiene rubber latex in the wet mixing step, additional elastomer is additional butadiene rubber. According to some other embodiments, the elastomer latex used in the wet mixing step is SBR, and additional elastomer is butadiene rubber. In such embodiments, butadiene rubber can be 10 weight % to 90 weight % of total elastomer in the elastomer composite blend. According to some other embodiments, the elastomer latex used in the wet mixing step is SBR, and the additional elastomer is natural rubber. In such embodiments, natural rubber can be the main component or phase, such as 50% to 90% by weight of the total elastomer in the elastomer composite blend. In some embodiments, SBR is used in both the wet mixing and dry mixing steps, thus being substantially 100% of the elastomer in the elastomer composite blend.

[0091] As further noted below, in addition to elastomer and filler, rubber composition can contain curing agent (curing agent), coupling agent and optional various processing aids, oil filler and antidegradant. In this regard, it should be understood that the elastomer composite blend disclosed herein includes vulcanized composition (VR), thermoplastic vulcanizate (TPV), thermoplastic elastomer (TPE) and thermoplastic polyolefin (TPO). TPV, TPE and TPO materials are further classified according to their ability to extrude and mold several times without substantially losing performance characteristics. Thus, when manufacturing elastomer composite blends, one or more curing agents can be used, such as sulfur, sulfur donor, activator, accelerator, peroxide and other systems for realizing the vulcanization of elastomeric composition.

[0092] When the elastomer latex used in the wet mixing step comprises natural rubber latex, the natural rubber latex may comprise fresh latex or latex concentrate (e.g., prepared by evaporation, centrifugation, or creaming). Natural rubber latex must of course be suitable for coagulation by carbon black. Latex is usually provided in an aqueous carrier liquid. Alternatively, the liquid carrier may be a hydrocarbon solvent. In any case, the natural rubber latex fluid must be suitable for continuous feeding into the mixing zone at an appropriate speed, pressure, and controlled concentration. The known instability of natural rubber latex is advantageously adapted because it is subjected to relatively low pressure and low shear in the entire system until it is entrained into the aforementioned semi-confined turbulence when encountering the extremely high speed and kinetic energy of the carbon black slurry in the mixing zone. In some embodiments, for example, natural rubber is fed into the mixing zone at a feed rate of about 3-12 feet / second, for example, about 4-6 feet / second, at a pressure of about 5psig. Benefiting from the knowledge of the selection criteria generally recognized in the disclosure and industry, selecting suitable latex or latex blends will be within the capabilities of those skilled in the art.

[0093] A particulate filler fluid containing salt, such as a carbon black slurry containing calcium chloride, is fed to the mixing zone at the inlet end of the coagulation reactor 14 through a feed line 16. The slurry may contain any suitable filler in a suitable carrier fluid. The choice of carrier fluid will depend primarily on the choice of particulate filler and system parameters. Aqueous and non-aqueous liquids may be used, with water being available in many embodiments for its cost, availability, and suitability for use in the production of carbon black and certain other filler slurries.

[0094] When a carbon black filler is used, the choice of carbon black will depend primarily on the intended use of the elastomer composite blend. Optionally, the slurry further includes any material that can be slurried and fed to the mixing zone according to the principles disclosed herein. Suitable additional particulate fillers include, for example, conductive fillers, reinforcing fillers, fillers containing short fibers (usually having an L / D aspect ratio of less than 40), flakes, and the like. Thus, exemplary particulate fillers that can be used to produce elastomer masterbatches according to the methods and apparatus disclosed herein are carbon black, fumed silica, precipitated silica, coated carbon black, chemically functionalized carbon blacks such as those with attached organic groups, and silicon-treated carbon blacks, alone or in combination with one another. Silicon-treated carbon blacks, silicon-containing species such as silicon oxides or carbides, are distributed as an inherent part of carbon black on at least a portion of the carbon black aggregates. Conventional carbon black exists in the form of aggregates, wherein each aggregate consists of a single phase, and the single phase is carbon. The phase can exist in the form of graphite crystallites and / or amorphous carbon, and is generally a mixture of these two forms. As discussed elsewhere herein, carbon black aggregates can be modified by depositing silicon-containing species such as silicon dioxide on at least a portion of the surface of the carbon black aggregates. The result can be described as silicon-coated carbon black. The materials described herein as silicon-treated carbon blacks are not carbon black aggregates that have been coated or otherwise modified, but actually represent different types of aggregates. In silicon-treated carbon blacks, the aggregates contain two phases. One phase is carbon, which will still exist as graphite crystallites and / or amorphous carbon, and the second phase is silicon dioxide (and possible other silicon-containing species). Thus, the silicon-containing species phase of the silicon-treated carbon black is an inherent part of the aggregate; it is distributed throughout at least a portion of the aggregate. It should be understood that multiphase aggregates are completely different from the silicon dioxide-coated carbon blacks mentioned above, which consist of pre-formed single-phase carbon black aggregates with silicon-containing species deposited on their surfaces. Such carbon blacks can be surface-treated so as to place silica functional groups on the surface of the carbon black aggregates. In this method, an existing aggregate is treated so that silicon dioxide (and possibly other silicon-containing species) is deposited or coated on at least a portion of the surface of the aggregate. For example, an aqueous sodium silicate solution can be used to deposit amorphous silicon dioxide on the surface of carbon black aggregates in an aqueous slurry at a high pH (such as 6 or higher). More specifically, carbon black can be dispersed in water to obtain an aqueous slurry consisting of, for example, about 5% by weight of carbon black and 95% by weight of water. The slurry can be heated to above about 70°C, such as to 85-95°C, and the pH can be adjusted to above 6, such as to a range of 10-11, with an alkaline solution. A separate formulation is made of a sodium silicate solution and an acidic solution that brings the sodium silicate solution to a neutral pH, the sodium silicate solution containing the amount of silicon dioxide desired to be deposited on the carbon black. The sodium silicate and acid solution are added dropwise to the slurry, which is maintained at its starting pH with an acid or alkaline solution as appropriate. The temperature of the solution is also maintained.The recommended addition rate of the sodium silicate solution is to calibrate the dropwise addition so as to add about 3% by weight of silicic acid relative to the total amount of carbon black per hour. During the addition process, and after its completion, the slurry can be stirred for several minutes (e.g., 30) to several hours (i.e., 2-3). In contrast, silicon-treated carbon black can be obtained by manufacturing carbon black in the presence of a volatilizable silicon-containing compound. Such carbon black can be made in a modular or "staged" furnace carbon black reactor having a combustion zone, a subsequent diameter convergence zone, a raw material injection zone with a restricted diameter, and a reaction zone. The quenching zone is located downstream of the reaction zone. Typically, a quenching fluid (usually water) is sprayed into the stream of newly formed carbon black particles flowing out of the reaction zone. When producing silicon-treated carbon black, the previously mentioned volatilizable silicon-containing compound is introduced into the carbon black reactor at a position upstream of the quenching zone. The compounds that can be used are compounds that are volatile at the carbon black reactor temperature. Examples include, but are not limited to, silicates such as tetraethoxy orthosilicate (TEDS) and tetramethoxy orthosilicate, silanes such as tetrachlorosilane and trichloromethylsilane; and organosilicon polymers such as octamethylcyclotetrasiloxane (OMTS). The flow rate of the volatile compound will determine the weight percent of silicon in the treated carbon black. The weight percent of silicon in the treated carbon black is typically about 0.1% to 25%, such as about 0.5% to about 10%, and about 2% to about 6%. The volatile compound can be premixed with the carbon black forming feedstock and introduced into the reaction zone with the feedstock. Alternatively, the volatile compound can be introduced separately into the reaction zone upstream or downstream of the feedstock injection point.

[0095] As noted above, additives may be used, and in this regard, coupling agents used to couple silica or carbon black should be expected to be useful with silicon-treated carbon black.Carbon black and many additional suitable particulate fillers are commercially available and are known to those skilled in the art.

[0096] The selection of a mixture of particulate fillers or particulate fillers will depend primarily on the intended use of the elastomer composite blend. The particulate fillers used herein may include any material that can be slurried and fed to a mixing zone according to the principles disclosed herein. Suitable particulate fillers include, for example, conductive fillers, reinforcing fillers, fillers containing short fibers (typically having an L / D aspect ratio of less than 40), flakes, and the like. In addition to the above-mentioned carbon black and silica fillers, fillers may be formed of clay, glass, polymers such as aramid fibers, and the like. Thanks to the present disclosure, it will be within the capabilities of those skilled in the art to select particulate fillers suitable for the methods and apparatus disclosed herein, and it is expected that any filler suitable for an elastomer composition can be mixed into an elastomer composite using the teachings of the present disclosure. Of course, blends of the various particulate fillers discussed herein may also be used.

[0097] It is to be understood that carbon black with a lower surface area per unit weight must be used at a higher concentration in the particle slurry to obtain the same coagulation effect as a carbon black with a higher surface area per unit weight at a lower concentration. The agitated mixing tank 18 receives water, salt and carbon black, such as optional pelletized carbon black, to prepare an initial mixture fluid. Such a mixture fluid enters a fluid pipeline 22 equipped with a pumping device 24 (such as a diaphragm pump, etc.) through a discharge port 20. Pipeline 28 sends the mixture fluid to a colloid mill 32, or a pipeline grinder, etc. through an inlet 30. The carbon black is dispersed in an aqueous carrier liquid to form a dispersion fluid, which is sent to a homogenizer 34 through an outlet 31 and a fluid pipeline 33. A pumping device 36 (such as a screw pump, etc.) is provided in pipeline 33. Homogenizer 34 disperses the carbon black more finely in the carrier liquid to form a carbon black slurry that is fed to the mixing zone of the coagulation reactor 14. It has an inlet 37 that is connected to the pipeline 33 fluid from the colloid mill 32. Typically, the slurry prepared according to the above system will have at least about 90% of the agglomerates less than about 30 microns in size, for example, at least about 90% of the agglomerates less than about 20 microns in size. The carbon black can be crushed to an average size of 5-15 microns, for example, about 9 microns. The outlet 38 sends the carbon black slurry from the homogenizer to the mixing zone through the feed line 16. The slurry can reach 10,000 to 15,000 psi in the homogenizer step and leave the homogenizer at about 600 psi or higher. A high carbon black content can be used to reduce the task of removing excess water or other carriers. In some embodiments, about 10 to 30% by weight of carbon black is used. With the benefit of this disclosure, those skilled in the art will recognize that the carbon black content (in % by weight) of the slurry to the mixing zone and the slurry flow rate should be coordinated with the natural rubber latex flow rate to the mixing zone to achieve the desired carbon black content (in phr) in the masterbatch. The carbon black content will be selected according to known principles to obtain material properties and performance properties suitable for the intended application of the product. Typically, for example, carbon black having a CTAB value of 10 or greater is used in an amount sufficient to achieve a carbon black content of at least about 30 phr in the masterbatch.

[0098] The slurry can be used for masterbatch production immediately after preparation. The fluid conduits and any optional storage tanks, etc. that transport the slurry should establish or maintain conditions that substantially maintain the dispersion of carbon black in the slurry. That is, a large amount of reaggregation or sedimentation of particulate fillers in the slurry should be prevented or reduced to the extent reasonably practicable. In some embodiments, all flow lines are smooth with smooth inter-line interconnections. Optionally, a reservoir is used between the homogenizer and the mixing zone to reduce fluctuations in the slurry pressure or velocity at the tip of the slurry nozzle in the mixing zone.

[0099] Under appropriate process parameters as described above, the natural rubber latex fluid or other elastomer latex fluid fed into the mixing zone via feed line 12 and the carbon black slurry fed into the mixing zone via feed line 16 can produce a new type of elastomer composite material, especially elastomer masterbatch crumbs. A method for mixing various additives into an elastomer masterbatch can also be provided. An additive fluid containing one or more additives can be fed to the mixing zone as a separate feed stream. If appropriate, one or more additives can also be premixed with the carbon black slurry, or more usually with the elastomer latex fluid. Subsequently, that is, during the dry mixing step, the additives can be mixed into the masterbatch. Many additives are well known to those skilled in the art, and include, for example, antioxidants, antiozonants, plasticizers, processing aids (such as liquid polymers, oils, etc.), resins, flame retardants, filler oils, lubricants and any mixtures thereof. The general use and selection of such additives are well known to those skilled in the art. With the help of this disclosure, their use in the system disclosed herein will be easily understood. According to certain alternative embodiments, a curing agent may be mixed in a similar manner to produce a curable elastomeric composite which may be referred to as a curable base stock.

[0100] The elastomer masterbatch crumbs are conveyed from the discharge end of the coagulation reactor 14 to a suitable drying device. Figure 1 In the embodiment of the present invention, the masterbatch crumbs undergo multi-stage drying. They are first conveyed to a dewatering extruder 40 and then conveyed to a drying extruder 42 via a conveyor or simple gravity descent or other suitable means 41. Figure 1 In some embodiments consistent with the production of natural rubber masterbatch with carbon black filler shown in , the dehydration / drying operation generally reduces the water content to about 0 to 1% by weight, such as 0.0 to 0.5% by weight. Suitable dryers are well known and commercially available, including, for example, extrusion dryers, fluidized bed dryers, hot air or other oven dryers, etc.

[0101] The dried masterbatch crumbs from the drying extruder 42 are transported by a cooling conveyor 44 to a baler 46. The baler is Figure 1 An optional, advantageous feature of the apparatus wherein dried masterbatch crumbs are compressed in a chamber into dimensionally stable compressed blocks or the like. Typically, 25 to 75 pound quantities of the elastomer masterbatch are compressed into blocks or bags for transport, further processing, etc. Alternatively, the product is provided in pellet form, for example by chopping the crumbs.

[0102] Suitable for Figure 1 The size and specific design features of the coagulation reactor 14 (including the mixing zone / coagulation zone assembly) of embodiments will depend in part on design factors such as the desired throughput, the choice of material to be processed, and the like. Figure 2An embodiment is shown in FIG. 4 , in which a coagulation reactor 48 has a mixing head 50 connected to a coagulation zone 52 with a fluid-tight seal at a joint 54 . Figure 2 A first subsystem 56 for feeding elastomer latex into the mixing zone, a subsystem 57 for feeding carbon black slurry or other particulate filler fluid into the mixing zone, and a subsystem 58 for feeding optional additive fluids, pressurized air, etc. into the mixing zone are schematically shown. It can be seen that the mixing head 50 has three feed channels 60, 61, 62. Feed channel 60 is provided for natural rubber latex fluid, and feed channel 62 is provided for direct feeding of gas and / or additive fluid. With respect to embodiments employing direct injection of additives, significant advantages are achieved in relation to hydrocarbon additives or more generally to water-insoluble additives. Although it is known to use an emulsion intermediate to produce an additive emulsion suitable for premixing with an elastomer latex, embodiments according to the present disclosure employing direct injection of additives can not only eliminate the need for an emulsion intermediate, but can also eliminate equipment previously used to form emulsions such as tanks, dispersion equipment, etc. Therefore, manufacturing costs and complexity can be reduced. As discussed further below, the feed channel 61 through which the slurry is fed to the mixing zone can be coaxial with the mixing zone and the coagulation zone of the coagulation reactor. Although only a single feed channel is shown to receive the elastomer latex fluid, any suitable number of feed channels can be arranged around a central feed channel through which the slurry is fed to the mixing zone. Thus, for example, Figure 2 In an embodiment of the invention, a fourth feed channel may be provided through which ambient air or high pressure air or other gas is fed to the mixing zone. Pressurized air may also be injected with the slurry through the central axial feed channel 61. The auxiliary feed channels may be temporarily or permanently sealed when not in use.

[0103] It can be seen that the coagulation zone 52 of the coagulation reactor 48 has a first portion 64 having an axial length that can be selected according to the design objectives of the intended specific application. Optionally, the coagulation zone can have a constant cross-sectional area over its entire or substantially entire axial length. Thus, for example, the coagulation reactor can define a simple, straight tubular flow channel from the mixing zone to the discharge end. The cross-sectional area of ​​the coagulation zone 52 gradually increases from the inlet end 66 to the discharge end 68. More specifically, the cross-sectional area can increase in the longitudinal direction from the inlet end to the discharge end. Figure 2 In the embodiment of the present invention, the cross-sectional area of ​​the condensation zone increases gradually, that is, it increases continuously after the constant cross-sectional portion 64. Unless otherwise specified, references to the diameter and cross-sectional area of ​​the condensation reactor (or more appropriately, the condensation zone defined within the condensation reactor) and other components are intended to refer to the cross-sectional area of ​​the open flow channels and the inner diameter of such flow channels.

[0104] It can be seen that the elastomeric composite material, specifically the coagulated elastomeric latex in the form of masterbatch crumbs 72, is discharged from the coagulation reactor 48 through the diverter 70. The diverter 70 is an adjustable conduit connected to the coagulation reactor at the discharge end 68. It is adjustable so as to selectively deliver the elastomer masterbatch crumbs 72 to any of a variety of different receiving locations. This feature advantageously facilitates the removal of masterbatch crumbs from the product stream, such as for testing or at the beginning of a production run (when initial process instabilities may temporarily result in inferior product). In addition, the diverter provides design flexibility to direct the product from the coagulation reactor to different post-processing paths. According to Figure 1 In the embodiment of FIG. 4 , it can be seen that the masterbatch chips 72 discharged from the coagulation reactor 48 through the diverter 70 are received by the dryer 40 .

[0105] It can be seen that the cross-sectional dimensions of the coagulation reactor 48 increase at the overall angle α between the inlet end 66 and the discharge end 68. Angle (α is greater than 0°, and may be less than 45°, less than 15°, or 0.5° to 5°). Angle α is considered a half angle because it is measured from the central longitudinal axis of the coagulation zone to point A at the outer circumference of the coagulation zone at the end of the coagulation reactor. In this regard, it should be understood that the cross-sectional area of ​​the upstream portion of the coagulation reactor (i.e., the portion near the inlet end 66) can be increased slowly enough to achieve the quasi-molding of the coagulation according to the principles discussed above. Excessive expansion angles of the coagulation zone may result in the elastomer masterbatch not being produced in the form of desirable pellets or worms, and cannot be simply sprayed through the coagulation reactor. In certain embodiments, increasing the inner diameter of the coagulation reactor too slowly may result in the blocking or clogging of the feed and reaction products entering the mixing head. In the downstream portion of the coagulation zone where the latex has been substantially coagulated and the flow has been substantially a plug flow, the coagulation zone may extend with or without increasing the cross-sectional area. Thus, references herein to a condensation zone having a gradually increasing cross-sectional area should be understood to refer primarily to that portion of the condensation zone where the flow is not substantially plug flow.

[0106] The cross-sectional area of ​​the condensation zone (i.e., at least the upstream portion thereof, as discussed immediately above) may be increased in steps rather than in increments. Figure 2 The continuous manner shown in the embodiment of FIG. Figure 3 In the embodiment shown in FIG. 1 , it can be seen that a continuous flow system for producing an elastomer masterbatch according to the methods and apparatus disclosed herein includes a mixing head / coagulation zone assembly in which the cross-sectional area of ​​the coagulation zone increases in a stepwise manner. In such a stepwise embodiment, a single segment of the coagulation zone has a streamlined connection to an adjacent segment. That is, they combine to form a smooth and generally continuous coagulation zone surface, as opposed to, for example, a sharp or instantaneous increase in diameter from one segment to the next. Figure 3The coagulation zone of the reactor increases in three steps, so that there are four different sections or sub-regions 74-77. Consistent with the design principles discussed immediately above, the cross-sectional area of ​​the coagulation zone 53 increases at an overall angle from the inlet end 66 to the point A at the discharge end 68, which achieves the necessary flow control in the upstream portion of the coagulation reactor. The first section 74 can be considered to include (a) a constant diameter portion of the mixing head 50 immediately downstream of the mixing zone, and (b) a portion of the same or similar diameter connected thereto at the joint 54 at the inlet end 66. The first section has a constant cross-sectional diameter D 1 and axial dimension or length L 1 In the first section 74, the length L 1 Can be larger than diameter D 1 Three times, for example, greater than D 1 Five times of D 1 Typically, this segment will have D 1 Each subsequent segment may have a constant cross-sectional dimension and a cross-sectional area that is approximately twice that of the previous (i.e., upstream) segment. Thus, for example, segment 75 has a constant cross-sectional dimension and a cross-sectional area that is twice that of segment 74. Similarly, the cross-sectional area of ​​segment 76 is twice that of segment 75, and the cross-sectional area of ​​segment 77 is twice that of segment 76. In each of segments 75-77, the length may be greater than three times its diameter, for example, approximately three to seven times its diameter, and typically approximately five times its diameter. Thus, for example, in segment 76, the longitudinal dimension L 3 It can be its diameter D 3 About five times as much.

[0107] exist Figure 4 The middle part shows the corresponding Figure 3 The mixing head and coagulation zone assembly of the embodiment of the present invention. The mixing head 50 is integral with the coagulation zone extender 53 via a joint 54. It defines a mixing zone, in which a plurality of feed channels 60, 61, 62 form a junction, and an elongated, substantially cylindrical channel 80 is substantially coaxial with the coagulation zone portion within the extender 53. It will be appreciated that precisely defining the boundaries of the mixing zone and / or coagulation zone is not critical to the operability of the methods and apparatus disclosed herein. It will be apparent to those skilled in the art having the benefit of this disclosure that many variations are possible in the design of the flow channel junction region. In this regard, in Figure 4In embodiments of the type shown, for example, the slurry tip 67 is generally upstream of the beginning of the cylindrical portion 80, approximately longitudinally centered in the junction of the feed channels. In such embodiments, the minimum cross-sectional area defined by an imaginary cone from the slurry tip 67 to the circumferential perimeter of the beginning of the cylindrical portion 80 can advantageously be greater than or at least equal to the cross-sectional area of ​​the latex feed channel 60. In some embodiments, both the channel 80 and at least the upstream portion of the coagulation zone where flow turbulence exists before the elastomeric latex is substantially completely coagulated have circular cross-sections.

[0108] It can be seen that the means for feeding the carbon black slurry or other particulate filler fluid comprises a feed tube 82 extending substantially coaxially with the mixing chamber to an opening or slurry nozzle tip 67 which opens toward the coagulation zone. As mentioned above, the carbon black slurry is fed into the mixing zone at a very high velocity relative to the feed velocity of the latex, and the axial arrangement of the narrow inner diameter feed tube 82 results in good development of flow turbulence. The diameter D of the passage 80 is m (As discussed above, it may be substantially equal to the diameter D of the immediately following portion of the segment 74 of the condensation zone. 1 ) may be at least twice the inner diameter of the slurry feed tube 82 (e.g., about four to eight times the diameter of the feed tube 82 or about seven to eight times the diameter). It can be seen that the feed tube 82 forms a liquid-tight seal with the inlet 83 at the upstream end of the feed channel 61 of the mixing head 50. The diameter of the axial feed tube 82 is largely determined by the required volume flow rate and the axial velocity of the slurry as it enters the mixing chamber through the slurry nozzle tip 67. With the benefit of this disclosure, one skilled in the art can easily determine the correct or required volume and velocity, and the volume and velocity will vary in part with the concentration and selection of the material. Embodiments in which the feed tube for carbon black slurry is removable (such as the embodiments described and disclosed herein) provide desirable flexibility in manufacturing different masterbatch compositions at different times. A feed tube used in one production run can be removed and replaced by a larger or smaller bore tube suitable for subsequent production. Taking into account the pressure and velocity of the slurry leaving the feed tube, it can be referred to as a spray or jet entering the mixing zone. In at least some embodiments, this should be understood as injecting the slurry at high speed into an area that is already substantially filled with fluid. Thus, it is a spray in the sense that it is distributed immediately when passing through the slurry nozzle tip, and not necessarily in the sense of free-flying droplets of material in a simple propagating trajectory.

[0109] It can be seen that the additional feed channels 60 and 62 form joints 84, 85 with the feed channel 60 and the downstream channel 80, respectively, at an angle β. In many embodiments, the angle β may have a value greater than 0° to less than 180°. Typically, β may be, for example, 30°-90°. It is desirable to avoid negative pressure, i.e., cavitation of the latex fluid when the latex fluid is entrained by the high-speed slurry exiting at the slurry nozzle tip 67, as this may adversely cause inconsistent mixing, resulting in inconsistent masterbatch products. Air or other gases may be injected or otherwise fed into the mixing zone to help break any such vacuum. In addition, the expanded feed line for natural rubber latex leading to the inlet 86 of the feed channel 60 desirably acts as a latex fluid reservoir. At Figure 4 In the embodiment of the present invention, the latex feed channel 60 intersects the mixing zone adjacent to the slurry nozzle tip 67. However, alternatively, the latex feed channel can intersect the mixing channel upstream or downstream of the slurry nozzle tip 67.

[0110] The carbon black slurry or other particulate filler fluid is typically supplied to the feed pipe 82 at a pressure greater than about 300 psig, such as about 500 to 5000 psig, for example about 1000 psig. In some embodiments, the liquid slurry is fed into the mixing zone through the slurry nozzle tip 67 at a velocity greater than 100 ft / sec, such as about 100 to about 800 ft / sec, or about 200 to 500 ft / sec, for example about 350 ft / sec. Figure 4 Arrows 51 in the Figures represent the general flow direction of the elastomeric latex and the auxiliary feed materials through the feed passages 60 and 62 into the passage 80 below the slurry nozzle tip 67. Thus, according to the above figures, the slurry and latex fluids are fed to the mixing zone at very different feed stream velocities. While not wishing to be bound by theory, it is presently understood that the differential feeding achieves latex shear conditions in the mixing zone, resulting in good macroscopic dispersion and coagulation.

[0111] exist Figure 5 and 6 An alternative embodiment is shown in Figure 4 The single axial feed tube 82 in the embodiment of the present invention is replaced by a plurality of axially extending feed tubes 90-92. Even a larger number of feed tubes can be used, for example up to about 6 or 8 axially extending feed tubes. Advantageously, production flexibility is achieved by using different feed tubes of different diameters for producing different formulations. In addition, multiple feed tubes can be used simultaneously in order to achieve good flow turbulence in the mixing zone and the coagulant zone of the coagulant reactor.

[0112] Figure 7An alternative embodiment of a mixing head is shown. It can be seen that the mixing head 150 defines a mixing zone 179. The axial feed channel 161 receives a feed tube 182 suitable for feeding a carbon black slurry or other particulate filler fluid containing salt into the mixing chamber 179 at a high speed. It can be seen that the center hole (bore) in the feed tube 182 terminates at the slurry nozzle tip 167. The constant diameter nozzle block (1and) 168 is immediately upstream of the slurry nozzle tip 167, resulting in a larger hole area 169. The axial dimension of the block 168 can be approximately 2 to 6 times its diameter, for example approximately 5 times. The second feed channel 160 forms a joint 184 with the mixing zone 179 at a 90° angle for feeding the elastomer latex fluid into the mixing zone. The cross-sectional diameter of the latex fluid feed channel 160 is much larger than the cross-sectional diameter of the slurry nozzle tip 167 and the block 168. Without wishing to be bound by theory, the axial extension of the nozzle block 168 coupled with the expanded diameter bore section upstream of the nozzle block is believed to provide favorable stability in the flow of slurry through the feed tube 182 into the mixing zone 179. It has been found that the bore of the feed tube 182 works well with a 20° chamfer, i.e., the tapered region 169 expands at an angle of approximately 20° in the upstream direction. Downstream of the mixing zone 179 is an elongated coagulation zone. Consistent with the principles discussed above, such a coagulation zone need only be slightly elongated. That is, its axial dimension need only be slightly longer than its diameter. Gradually increasing coagulation zones may be used.

[0113] As mentioned above, the coagulation of the elastomer masterbatch is basically completed at or before the end of the coagulation reactor. That is, coagulation occurs without the need to add a stream of a coagulant solution or the like. Coagulation can occur in a mixing zone. For this reason, the mixing zone can be regarded as all or part of a coagulation zone. Moreover, the mention of substantially complete coagulation before the elastomer masterbatch leaves the coagulation reactor does not mean the exclusion of the possibility of subsequent processing and subsequent treatment steps for any of the various purposes suitable for the intended use of the final product. In this regard, substantially complete coagulation in some embodiments of the new method for using natural rubber latex disclosed herein refers to coagulation of at least about 95% by weight of the rubber hydrocarbons of the latex, such as coagulation of at least about 97% by weight and coagulation of at least about 99% by weight.

[0114] Prior to adding the additional elastomer in the dry mixing step of the wet / dry process disclosed herein, the masterbatch (or other elastomeric composite) produced by the wet mixing step is optionally subjected to any suitable further processing. Apparatus suitable for the dry mixing step is commercially available and will be apparent to those skilled in the art with the benefit of this disclosure. Suitable dry mixing equipment includes, for example, a Banbury mixer, an open mill, a roller mixer, and the like. The coagulum from the wet mixing step, with or without any further intermediate treatment, is introduced into a Banbury mixer or other mixing device with the additional elastomer in any suitable order and relative proportion suitable for the intended use or application. With the benefit of this disclosure, it will be within the capabilities of those skilled in the art to determine the appropriate order of addition and relative proportion of the wet mixed product and the additional elastomer. Similarly, with the benefit of this disclosure, it will be within the capabilities of those skilled in the art to select suitable additional ingredients to be added during the dry mixing step suitable for the intended use or application, such as extender oils, curing agents, and other additives known for the general type of elastomeric composites and elastomeric composite blends disclosed herein.

[0115] The method and apparatus disclosed and described herein produce elastomer composite blends with excellent physical properties and performance characteristics. The novel elastomer composite blend includes a masterbatch composition produced by the above method and apparatus, as well as an intermediate rubber compound and a finished product manufactured by such a masterbatch composition. It is noteworthy that the elastomer masterbatch can be produced using natural rubber latex (latex concentrate or fresh latex) and various grades of carbon black filler, with excellent physical properties and performance characteristics. Carbon blacks currently widely used in applications such as tire treads, as well as carbon blacks that have been considered unsuitable for commercial use in known production equipment and methods, have been successfully used. Those carbon blacks that are not suitable for achieving acceptable levels of macroscopic dispersion and / or maintaining the molecular weight of the elastomer at conventional commercial loading levels of carbon black due to their high surface area and low structure can be used for certain applications of the novel elastomer composite blend disclosed herein. It is found that such elastomer composite blends have excellent dispersion of carbon black in elastomers. In addition, these favorable results are achieved without the need for a coagulation step involving a treatment tank or an acid solution or other coagulant logistics. Thus, not only the cost and complexity of such coagulant treatments may be avoided, but also the need to treat the effluent streams generated by such operations may be avoided.

[0116] The known dry mastication techniques of the prior art cannot achieve equal dispersion of fillers in elastomer composite blends without significant molecular weight degradation, and therefore cannot produce new natural rubber compositions manufactured according to some embodiments. In this regard, novel elastomer composite blends are disclosed herein, which have excellent macroscopic dispersion of carbon black (even carbon black with a structure to surface area ratio DBPA:CTAB less than 1.2 and even less than 1.0) in natural rubber, and high molecular weight of natural rubber. Past known mixing techniques could not achieve such excellent macroscopic dispersion of carbon black without significantly reducing the molecular weight of natural rubber, and therefore could not produce novel masterbatch compositions and other elastomer composites. Elastomer composite blends according to the present disclosure can have a level of macroscopic distribution of carbon black that has not been achieved so far, and can be used to replace elastomeric materials known in the prior art with poor macroscopic dispersion. Thus, the elastomer composite blends disclosed herein can be used as cured rubbers according to known techniques. Such novel cured rubbers can have physical properties and performance properties comparable to other comparable cured rubbers containing masterbatches with poor macroscopic dispersion and significantly better in some cases. Elastomeric composite blends may be produced in accordance with the present disclosure with reduced mixing time, reduced energy input, and / or other cost savings.

[0117] The carbon black structure used herein can be measured as dibutyl phthalate adsorption (DBPA) value (expressed as cubic centimeters of DBPA / 100 grams of carbon black) according to the procedure described in ASTM D2414. The carbon black surface area can be measured as CTAB (expressed as square meters per gram of carbon black) according to the procedure described in ASTM D3765-85. It should be recognized that other factors that affect the dispersion level achievable using the methods and apparatus disclosed herein include the concentration of carbon black in the slurry, the total energy input into the slurry, and the energy input during the mixing of the fluid streams, etc.

[0118] The macroscopic dispersion quality of the carbon black in the natural rubber masterbatch disclosed herein is significantly better than that of carbon black having approximately the same MW sol In some embodiments, the MW of natural rubber in the fresh latex state (e.g., about 1,000,000) is approximately equal to that of natural rubber in the fresh latex state (e.g., about 1,000,000). sol Excellent carbon black distribution is achieved, which has not been achieved before. Using carbon blacks with low structure and high surface area, such as having less than 100 cc / 100 g DBPA, greater than 45 to 65 m 2 The carbon black having a CTAB content of less than 0.1 g / g and a DBPA:CTAB ratio of less than 1.2 (e.g., less than 1.0) has a particularly significant advantage in dispersion quality.

[0119] This written specification uses examples to disclose the present disclosure, including the best mode, and to enable any person skilled in the art to make and use the present disclosure. Other examples that occur to those skilled in the art are intended to be within the scope of the present disclosure if they have structural elements that are not different from the same concept or if they include equivalent structural elements with insubstantial differences. It is to be recognized that variations of the above-disclosed and other features and functions, or alternatives thereto, may be combined into many other different systems or applications. Various currently unforeseen or unexpected substitutions, modifications, changes or improvements may subsequently be made by those skilled in the art, which are also intended to be covered by the following claims.

Claims

1. A method for producing a masterbatch, comprising: The elastomer latex, particulate filler and salt are mixed in a coagulation chamber.

2. The method of claim 1, wherein the particulate filler comprises carbon black.

3. The method of claim 1, wherein the elastomer latex comprises natural rubber.

4. The method of claim 1, further comprising: continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and A second composition comprising particulate filler and salt is continuously fed to the coagulation chamber.

5. The method of claim 4, wherein the second composition is fed to the coagulation chamber at a pressure of at least 300 psig; and / or wherein the second composition is fed to the coagulation chamber at a velocity of at least about 100 feet per second.

6. The process of claim 1, wherein said elastomer latex, said filler and said salt are provided to said coagulation reactor in separate streams.

7. The process of claim 1, wherein said elastomer latex and said salt are provided to said coagulation reactor in the same stream.

8. The method of claim 1, wherein an amount of salt is provided so that the salt concentration in the coagulation chamber matches the salt concentration required to make the magnitude of the zeta potential of the latex in the range of 30 to 15.

9. A method for producing an elastomeric composite blend, comprising: continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and continuously feeding a second composition comprising a particulate filler and a salt into a coagulation chamber, wherein the first composition and the second composition are mixed in the coagulation chamber to form a masterbatch; and The masterbatch is dry blended with additional elastomer to form an elastomeric composite blend.

10. A masterbatch produced by a process comprising: continuously feeding a first composition comprising an elastomeric latex into a coagulation chamber; and continuously feeding a second composition comprising a particulate filler and a salt into a coagulation chamber at a velocity of at least about 100 feet per second; The first composition and the second composition are mixed in a coagulation chamber to form a masterbatch.

Images