METHODS FOR PREPARING A COMPOSITE COMPRISING A NEVER-DRIED RUBBER AND A FILLER

Abstract

Described herein are methods of preparing composites from never-dried natural rubber. Also disclosed are composites made from never-dried natural rubber and a filler. Further disclosed herein is a method of preparing a composite in an integrated manufacturing operation, comprising producing a never-dried natural rubber from latex recovered from natural latex sources in a latex or rubber manufacturing facility. Also disclosed are products made from the composites described herein.

Description

Title of the invention: Methods for preparing a composite comprising a never-dried rubber and a filler FIELD OF THE INVENTION

[0001] Methods of making composites from never-dried rubber and a filler are described herein. The invention also relates to composites prepared from the methods described herein and corresponding vulcanizates. TECHNOLOGICAL BACKGROUND

[0002] There continues to be a desire in the rubber industry to develop methods for dispersing a filler in an elastomer, and it is particularly desirable to develop methods that can do so efficiently with respect to the quality, time, effort, and / or cost of dispersing a filler.

[0003] Natural rubber, used as an elastomer, is generally collected or harvested as a latex emulsion or coagulum (e.g., goblet lumps). The latex is formed into a coagulum by biological or other processes occurring in nature or by using acid or salt treatment, and is then generally washed. The washed coagulum, in the form of "crumbs" or sheets, is dried and supplied to the rubber industry in the form of baled crumbs or sheets. Drying natural rubber can require a large amount of energy and effort. In addition, during the drying process, thermal damage to the natural rubber can occur, particularly if the drying process is not controlled and monitored.

[0004] Many commercially important products are formed from elastomeric compositions in which a reinforcing filler material is dispersed in any of various synthetic elastomers, natural rubber, or blends of elastomers. Carbon black and silica, for example, are commonly used to reinforce natural rubber and other elastomers. It is common to produce a masterbatch, namely a premix of a reinforcing filler, an elastomer, and various optional additives, such as an extender oil. Such masterbatches can then be compounded with processing and curing additives and upon curing, generate many commercially important products.Such products include, for example, pneumatic and non-pneumatic or solid tires for vehicles, including the tread portion comprising a cap and base, an undertread, an inner rubber, a sidewall, a cord skin, a carcass, and others. Other products include, for example, engine mounts, bushings, . conveyor belts, windshield wiper blades, rubber components for aerospace and marine equipment, vehicle track elements, seals, liners, trims, wheels, bumpers, anti-vibration systems, and the like.

[0005] Good dispersion of reinforcing filler in rubber compounds has been identified as a factor in achieving mechanical strength and a uniform elastomeric composite, as well as rubber compounding performance. Considerable effort has been put into developing methods to improve dispersion quality, and various solutions have been proposed to address this challenge. For example, more intensive mixing may improve a reinforcing filler dispersion, but may degrade the elastomer in which the filler is dispersed. This is particularly problematic in the case of natural rubber, which is highly susceptible to mechanical / thermal degradation, especially under dry mixing conditions.

[0006] As an alternative to dry blending techniques, it is known to feed an elastomeric latex or polymer solution and a carbon black or silica slurry to a liquid blending system, e.g., a stirred tank. Such "liquid masterbatch" techniques can be used with natural rubber latex and emulsified synthetic elastomers, such as styrene-butadiene rubber (SDR), or other elastomeric polymers in liquid form. However, although such wet blending techniques have shown promise, batch wet blending can present challenges in manufacturing operations. Continuous or semi-continuous techniques for producing a liquid masterbatch, such as those described in U.S. Patents 6,048,923 and 8,586,651, have been effective in producing elastomer-filler composites characterized by high quality.However, these processes are limited to liquid forms of rubber, such as elastomeric latex or solution forms of rubber.

[0007] In view of the above, methods of using natural rubber without subjecting the natural rubber to complete drying processes could be economically advantageous and environmentally beneficial since less energy and processing would occur. Thus, there is a need to develop methods for incorporating filler into natural rubber in a less environmentally impactful manner while still achieving acceptable or improved elastomeric composite dispersion quality and functionality from elastomeric composite masterbatches, which may translate into acceptable or improved properties in corresponding vulcanized rubber compounds and rubber articles.

[0008] SUMMARY

[0009] The present invention relates to methods of preparing a composite, and more specifically to methods of preparing a composite using never-dried natural rubber and a filler and using one or more mixers.

[0010] One aspect of the invention relates to methods for preparing a composite of elastomer and filler(s), and more particularly, a composite comprising natural rubber and one or more fillers.

[0011] Another aspect of the invention relates to methods for preparing a composite in which the starting elastomer is a never-dried (wet) natural rubber. The never-dried natural rubber may comprise rubber and water in the form of a coagulum.

[0012] Another aspect is a method for preparing a composite, comprising the steps of:

[0013] charging a mixer separately with at least one never-dried natural rubber and a filler, wherein the never-dried natural rubber has water present in an amount in the range of 5% to 55% (e.g., the moisture level) by weight of the never-dried natural rubber;

[0014] in one or more mixing steps, mixing the at least one never-dried natural rubber and the filler to form a mixture, wherein in at least one of said mixing steps, carrying out said mixing at mixer temperatures controlled by at least one temperature control means. The mixing further involves removing at least some of the water from the mixture by evaporation; and

[0015] discharging, from the mixer, the composite comprising the filler dispersed in the natural rubber at a filler level of at least 20 phr (or other amounts described herein), and wherein the composite has a water content of not more than 5% by weight based on the total weight of said composite.

[0016] Another feature relates to a method of preparing a composite in an integrated manufacturing operation, comprising the steps of:

[0017] producing never-dried natural rubber from latex recovered from natural latex sources in a latex or rubber manufacturing facility;

[0018] transporting said never-dried natural rubber to at least one mixer;

[0019] charging said at least one mixer with at least one never-dried natural rubber and at least one filler; wherein the never-dried natural rubber has water present in an amount in the range of 5% to 55% by weight of the never-dried natural rubber;

[0020] in one or more mixing steps, mixing the at least one never-dried natural rubber and the filler to form a mixture, and in at least one of said mixing steps, performing said mixing at mixer temperatures controlled by at least one temperature control means, and removing at least a portion of the water from the mixture by evaporation; and

[0021] discharging, from the at least one mixer, the composite comprising the filler dispersed in the never-dried natural rubber at a filler level in the range of 1 to 100 phr, wherein the composite has a water content of not more than 5% by weight based on the total weight of said composite.

[0022] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: the never-dried natural rubber is a coagulum; the never-dried natural rubber is a coagulum formed by exposing natural rubber latex to air under ambient conditions; the never-dried natural rubber is a coagulum formed by exposing natural rubber latex to a salt or an acid or both; the never-dried natural rubber has said water present in an amount in the range of 10% to 40% by weight based on the total weight of the never-dried natural rubber; optionally, the never-dried natural rubber has said water present in an amount in the range of 20% to 30%.

[0023] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: the filler has a liquid content of less than 10% by weight, based on the weight of the filler, and is in the form of a powder or pellet; the filler is a wet filler comprising a filler moistened with a liquid, wherein the liquid is present in an amount determined based on OAN of the filler according to the equation k* OAN / ( 100+OAN) * 100, wherein k is in the range of 0.6 to 1.1; the filler is a wet filler comprising a filler moistened with a liquid, the wet filler having a liquid content of at least 10% by weight, based on the weight of the wet filler, and is in the form of a powder, paste, pellet, or cake; the liquid is an aqueous liquid.

[0024] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise any one or more of the following embodiments: the filler comprises at least one material selected from carbonaceous materials, carbon black, silica, nanocellulose, lignin, clays, nanoclays, metal oxides, metal carbonates, pyrolysis carbon, graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-walled carbon nanotubes, multi-walled carbon nanotubes, filler coated and treated therewith, and combinations thereof; the filler is selected from carbon black, silica, filler coated and treated therewith, and combinations thereof; treated filler is selected from carbon black, chemically treated carbon black, and chemically treated silica; the filler comprises a mixture of at least two fillers selected from carbon black, silica, and silicon-treated carbon black; the filler comprises carbon black; the filler comprises silica; the filler comprises silicon-treated carbon black.

[0025] With respect to any aspect, method or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: charging comprises charging at least the never-dried natural rubber into the mixer separately but within 20 minutes of charging the feedstock into the mixer; charging comprises charging the mixer with at least a portion of the never-dried natural rubber followed by charging the mixer with at least a portion of the feedstock; wherein when charging the mixer with at least a portion of the never-dried natural rubber, the never-dried natural rubber is heated to a temperature of 90°C or higher prior to charging the mixer with at least a portion of the feedstock; charging comprises charging the mixer with at least the feedstock followed by charging the mixer with the never-dried natural rubber;the charging comprises charging the mixer with at least the filler followed by charging the mixer with the never-dried natural rubber; the charging comprises multiple additions of the filler; wherein during the charging or mixing, the method further comprises adding at least one antidegradant, for example, the at least one antidegradant is N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine; the charging further comprises charging the mixer with an additional elastomer that is in addition to said never-dried natural rubber; the additional elastomer is the same as the never-dried natural rubber; the additional elastomer is different from the never-dried natural rubber to form an elastomeric composite blend.;

[0026] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: the mixture consists essentially of the never-dried natural rubber and the filler; the mixture consists essentially of the never-dried natural rubber and the filler; the mixture consists essentially of the never-dried natural rubber, the filler, and at least one antidegradant.

[0027] With respect to any aspect, method or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: a time period between the start of mixing and discharge is in the range of 5 min to 30 min, for example, in the range of 5 min to 15 min; during said mixing, the mixer comprises one or more rotors operating at a speed of peak of at least 0.5 m / s for at least 50% of the mixing time, for example, a peak speed of at least 0.6 m / s for at least 50% of the mixing time; the temperature of the at least one temperature control means may be set and maintained by one or more temperature control units (TCUs); the TCU can be set to a temperature in the range of 5°C to 150°C, 30°C to 150°C, 40°C to 150°C, or 50°C to 150°C, for example, 40°C to 125°C, 50°C to 125°C, 40°C to 110°C, 50°C to 110°C, 65°C to 150°C, 65°C to 100°C, 70°C to 100°C, 75°C to 100°C, 50°C to 100°C, or 40°C to 100°C.

[0028] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: one or more rubber chemicals are absent from the composite discharged in step (c); removing comprises removing at least 50% by weight of the water from the mixture by evaporation; removing at least a portion of the water from the mixture further comprises expressing, compacting, dewatering, or combinations thereof; mixing is carried out in one mixing step; mixing is carried out in two mixing steps; mixing is carried out in two mixing steps and the two mixing steps are carried out in the same mixer or in different mixers; the method is a batch process; the method is a continuous process.

[0029] With respect to any aspect, method, or embodiment described herein, where applicable, the method may further comprise one or more of the following embodiments: the composite comprises the filler dispersed in the natural rubber at a filler level in the range of 20 phr to 100 phr, or 30 phr to 70 phr, or other filler level ranges described herein; the discharged composite has a water content of not more than 2% by weight, for example not more than 1% by weight; upon discharge, said mixer has a temperature in the range of 120°C to 180°C; after discharge, the method further comprises mixing the composite with an additional elastomer; the additional elastomer is the same as the never-dried natural rubber; the additional elastomer is different from the never-dried natural rubber to form an elastomeric composite blend;after discharge, the method further comprises at least one additional processing step selected from extrusion, calendering, grinding, granulating, baling, compounding and sheeting. ;

[0030] Another aspect is a method of making a vulcanizate, comprising mixing any of the composites described herein with at least one curing agent and / or curing any of the composites described herein in the presence of at least one curing agent.

[0031] Another aspect is a tire component or article comprising the vulcanizates described herein. The item may be selected from tire treads, undertreads, inner rubbers, sidewall, sidewall inserts, cord skin, and cushion rubber for retreaded tires;the item can be selected from hoses, packings, liners, seals, gaskets, anti-vibration items, tracks, track pads for tracked vehicle equipment, engine mounts, seismic stabilizers, mining equipment screens, mining equipment packings, conveyor belts, chute liners, suspension pump liners, suspension pump wheels, valve seats, valve bodies, piston hubs, piston rods, plungers, wheels for mixing suspensions and suspension pump wheels, crusher liners, cyclones and hydrocyclones, expansion joints, packings for dredge pumps and outboard motor pumps for marine equipment, shaft seals for marine and propeller shafts. ;

[0032] It is to be understood that both the above general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention as claimed. DETAILED DESCRIPTION

[0033] One aspect relates, in part, to methods of preparing or forming a composite by blending a never-dried natural rubber with one or more fillers. This natural rubber may take the form of a coagulum and may be considered a wet natural rubber, as provided herein.

[0034] The most common process for the production of natural rubber involves forming a rubber coagulum from latex, washing the rubber coagulum, and then converting the coagulum into a crumb which is then dried by hot air in a continuous process. Most of the water is removed in less than half the total drying time. Removing the last 10% of the water can take a substantial portion of the total time. Without wishing to be bound by any theory, in the early stages of drying, water is removed by transport through aqueous channels in the rubber crumb followed by evaporation of moisture from the surface. In the later stages of drying, the aqueous channels become closed and water can escape only by diffusion through the rubber crumb, which can be a slow process. The crumbs in the coagulum are made as small as possible to minimize drying time.The dryer temperature is chosen to balance the need for rapid drying with the need to avoid polymer degradation, which can occur at temperatures . above 100°C.

[0035] A process of blending a never-dried natural rubber with a filler with simultaneous removal of at least some of the water may save time, cost, and / or provide a natural rubber with less degradation.

[0036] The composite formed by the methods described herein may be considered an uncured mixture of filler(s) and natural rubber(s), optionally with one or more additives, where the additives are described in more detail herein. The composite formed may be considered a blend or masterbatch. The composite formed may be, as an option, an intermediate product that may be used in a subsequent rubber compounding and one or more subsequent vulcanization processes.The composite, prior to compounding and vulcanization, may also be subjected to additional processes, such as one or more holding steps or one or more additional mixing steps, one or more additional drying steps, one or more extrusion steps, one or more calendering steps, one or more grinding steps, one or more granulating steps, one or more pressing steps, one or more twin-screw discharge extrusion steps, or one or more rubber machining steps, to obtain a rubber compound or rubber article.

[0037] Methods for preparing a composite include the step of separately charging or introducing into a mixer at least one never-dried natural rubber and a filler. The term "Never-dried natural rubber," as used herein, refers to natural rubber that is collected and / or harvested (rubber tapping) from rubber trees (e.g., Hevea latex or Hevea brasiliensis species) and / or from other natural latex sources and that has not been dried below the levels disclosed herein. The collected or harvested rubber may be in the form of a latex, which is a water-based emulsion or colloidal suspension of rubber particles, or a coagulum, e.g., a coagulum in the form of lumps, such as cup lumps. The harvested natural rubber may be a mixture of latex and coagulum.A coagulum can be formed by exposing latex to ambient conditions, for example, by allowing coagulation to occur through processes occurring in nature, for example, by exposing latex to the environment and / or by the action of microorganisms naturally present in latex. Ambient conditions generally involve the absence of external heat or external chemicals applied to the latex. For example, a coagulum can be formed when latex is exposed to air at ambient temperatures ranging from 15°C to 40°C. Coagulation can occur in a container that collects latex directly from a rubber tree where the container remains outdoors or is taken indoors, in either case, the coagulum can be formed under conditions. ambient.

[0038] Alternatively or additionally, the latex may be coagulated by human-performed steps, e.g., by the use of acid treatment, salt treatment, and / or heating (e.g., exposure to steam). Prior to coagulation, the latex may be preserved by the addition of preservatives known in the art, e.g., ammonia.

[0039] Natural rubber may optionally be chemically modified in some way, either before its coagulation or at the wet coagulation stage. For example, it may be treated to chemically or enzymatically modify or reduce various non-rubber components, or the rubber molecules themselves may be modified with various monomers or other chemical groups such as chlorine. Epoxidized natural rubber may be used.

[0040] During one or more of the processes described herein, whether the processes occur in nature or are carried out with artificial steps, some evaporation of water may occur, but the material is still considered wet, or never-dried, natural rubber. As an option, the never-dried natural rubber that is charged to the mixer (e.g., a coagulum) has water (moisture) present in an amount in the range of about 5 wt.% to about 55 wt.%, such as 15 wt.% to about 55 wt.% or more, based on the weight of the never-dried natural rubber. Alternatively, the term "never-dried natural rubber" may refer to natural rubber that is not dried, such that water is present in an amount of 5 wt.% or more, e.g., 10 wt.% or more, or 15 wt.% or more. In other words, the natural rubber is never dried prior to use in the processes disclosed herein.Thus, never-dried natural rubber is not dried natural rubber that has been baled. Some or all of the water (or moisture content) in never-dried natural rubber may be water naturally present in the coagulum and originating from the rubber tree or other natural latex source. Alternatively, some or all of the water present in never-dried rubber may result from a washing step. Some of the liquid, comprising primarily water, may flow from the coagulum either naturally, due to the elastic force provided by the rubber polymer, or by applying pressure to the wet coagulum.

[0041] With respect to the never-dried natural rubber that is used and blended with the filler, the natural rubber may be considered wet natural rubber or substantially wet natural rubber. For example, the natural rubber has a water content (or moisture content) of 5 wt% or more, 10 wt% or more, 15 wt% or more, based on the total weight of the wet natural rubber, such as 20 wt% or more, 25 wt% or more, 30 wt% or more, or 40 wt% or more. by weight or more, 35% by weight or more, or in the range of 5% by weight to 55% by weight, 10% by weight to 55% by weight, 15% by weight to 55% by weight, 15% by weight to 50% by weight, 15% by weight to 45% by weight, 15% by weight to 40% by weight, 20% by weight to 55% by weight, 20% by weight to 50% by weight, 20% by weight to 45% by weight, 20% by weight to 40% by weight, 25% by weight to 55% by weight, 25% by weight to 50% by weight, 25% by weight to 45% by weight, 25% by weight to 40% by weight, 25% by weight to 35% by weight, from 25% by weight to 30% by weight, from 30% by weight to 45% by weight, and the like.

[0042] Never-dried natural rubber or coagulum may comprise, consist essentially of, consist of, include a) coagulated rubber particles and b) non-rubber natural components or constituents and c) water (moisture). Never-dried natural rubber may contain, for example, a) from about 50 wt.% to 80 wt.% (e.g., from about 50 wt.% to 75 wt.%) coagulated rubber particles, b) from about 5 wt.% to 15 wt.% non-rubber components, and c) from about 15 wt.% to 55 wt.% water. Non-rubber natural components comprise, consist essentially of, consist of, or include: proteins, fatty acids, carbohydrates, lipids, free amino acids, sugar, organic acids, organic solutes, resins, and inorganic materials.The natural non-rubbery components may be primarily proteins, carbohydrates, resins and / or lipids.

[0043] Never dried natural rubber can be subjected to washing or a washing step can be completely avoided. Thus, never dried natural rubber as an option, can be never dried and never washed natural rubber, thus eliminating the washing step to simplify the process.

[0044] As an option, the never-dried natural rubber may be subjected to one or more steps to reduce the amount of water present in the never-dried natural rubber. For example, prior to loading in step (a), the never-dried natural rubber may be subjected to expression, extrusion, compaction and / or dewatering, or any combinations thereof to reduce the amount of water while maintaining a water content of 5% (or more) by weight.

[0045] The methods described herein include the step of separately charging or introducing into a mixer at least one never-dried natural rubber and a filler. The filler (dry or wet) and the never-dried natural rubber are introduced into the mixer as separate charges and are then mixed. Charging may occur in any manner, including, but not limited to, conveying, metering, pouring, and / or feeding into a batch, semi-continuous, or continuous flow of the never-dried natural rubber and the filler. in the mixer. The never-dried natural rubber and the filler are not introduced as a mixture into the mixer. The never-dried natural rubber and the filler may be added together or simultaneously, but not as a mixture (e.g., not when the filler is pre-dispersed in the natural rubber in which the natural rubber forms all or part (in the case of blends) of a polymeric continuous phase. The charging of the never-dried natural rubber and the charging of the filler may both occur at once, or sequentially, and may occur in any sequence.For example, (a) all of the never-dried natural rubber is added first, (b) all of the filler is added first, (c) all of the never-dried natural rubber is added first with a portion of the filler, followed by the addition of one or more remaining portions of the filler, (d) a portion of the never-dried natural rubber is added, then a portion of the filler is added, (3) a portion of the filler is added, then a portion of the undried natural rubber is added, or (f) at the same time, or at substantially the same time, all or a portion of the never-dried natural rubber and all or a portion of the filler are added as separate charges to the mixer. The never-dried natural rubber may be charged as one piece or multiple pieces (e.g., lumps) or as a loose particulate material.Multiple pieces of the never-dried natural rubber may be obtained by cutting or grinding (e.g., forming crumbs) the never-dried elastomer using methods well known in the art. The size of these pieces may have dimensions of at least 100 μm or at least 1 mm up to 10 cm or more, up to 5 cm, or up to 1 cm.

[0046] As an option, the never-dried natural rubber (in whole or in part) and the filler (in whole or in part) may be added to the mixer, but within 20 minutes of each other or within 15 minutes or within 10 minutes or within 5 minutes, or within 1 minute, within 30 seconds of each other, within 15 seconds of each other, or within 5 seconds of each other.

[0047] In typical dry blending processes in which the filler is dispersed throughout the solid natural rubber, the challenge is to ensure that the blending time is long enough to ensure sufficient filler incorporation and dispersion before the natural rubber in the blend encounters high temperatures and undergoes degradation. In typical dry blending processes, the blending time and temperature are controlled to avoid such degradation, and the ability to optimize filler incorporation and dispersion is often not possible.

[0048] In addition to reducing drying time and costs using the present methods, a Another advantage of the present mixing processes is the provision of water into the mix at the start of mixing, which may allow the batch time and temperature to be controlled beyond what is achievable with known dry mixing processes. Other benefits may be achieved, such as improved filler dispersion and / or facilitated rubber-filler interactions and / or improved rubber compound performance. In general, and as described herein, the mixing process may also be managed by controlling one or more mixer or process parameters.

[0049] With respect to the filler, the filler may be wet or dry. If more than one filler is used, all of the fillers may be wet or all may be dry or may be a combination of a wet and dry filler.

[0050] In their dry state, fillers may contain no or small amounts of liquid (e.g., water or water vapor) adsorbed on their surfaces. For example, carbon black may have 0 wt%, or from 0.1 wt% to 1 wt%, or up to 3 wt% or up to 4 wt% water (moisture) and precipitated silica may have a moisture content of from 4 wt% to 7 wt% water, e.g., from 4 wt% to 6 wt% water. Such fillers are referred to herein as dry or unmoistened fillers. For wet fillers, water or additional water may be added to the filler and is present on a substantial portion or substantially all surfaces of the filler, which may include interior surfaces or pores accessible to the liquid.In use, during mixing, at least a portion of this liquid may also be removed by evaporation when the wet filler is dispersed in the never-dried natural rubber. The wet filler may have a liquid content of at least 10% by weight relative to the total weight of the wet filler, i.e. at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50% by weight, or from 15% to 99%, from 15% to 95%, from 15% to 90%, from 15% to 80%, from 15% to 70%, from 15% to . 60%, from 15% to 65%, from 20% to 99%, from 20% to 95%, from 20% to 90%, from 20% to 80%, from 20% to 70%, from 20% to 60%, from 30% to 99%, from 30% to 95%, from 30% to 90%, from 30% to 80%, from 30% to 70%, from 30% to 60%, from 40% to 99%, from 40% to 95%, from 40% to 90%, from 40% to 80%, from 40% to 70%, from 40% to 60%, from 45% to 99%, from 45% to 95%, from 45% to 90%, from 45% to 80%, from 45% to 70%, from 45% to 60%, from 50% to 99%, from 50% to 95%, from 50% to 90%, from 50% to 80%, from 50% to 70%, or from 50% to 60% by weight, based on the total weight of the wet filler. The liquid content of the filler can be expressed as a percentage by weight: 100 * [liquid mass] / [liquid mass + dry filler mass].

[0051] Regarding the wet filler, in one embodiment, the wet filler has the consistency of a solid. As an option, a wet filler is moistened only to an extent that the resulting wet filler retains the shape of a powder, particulate, pellet, tablet, or paste, or a similar consistency, and / or has the appearance of a powder, particulate, pellet, tablet, or paste. The wet filler does not flow like a liquid (at zero applied stress). As an option, the wet filler may retain a shape at 25°C when molded into such a shape, whether individual particles, agglomerates, pellets, tablets, or pastes. In another embodiment, the wet filler may be a suspension. In yet another embodiment, the wet filler is not a filler suspension, and does not have the consistency of a liquid or suspension.

[0052] The liquid used to moisten the load may be, or include, an aqueous liquid, such as, but not limited to, water. The liquid may include at least one other component such as, but not limited to, base(s), acid(s), salt(s), solvent(s), surfactant(s), coupling agent(s), and / or processing aid(s), and any combinations thereof. More specific examples of the component are NaOH, KOH, acetic acid, formic acid, citric acid, phosphoric acid, sulfuric acid, or any combinations thereof. For example, the base may be selected from NaOH, KOH, and mixtures thereof, or the acids may be selected from acetic acid, formic acid, citric acid, phosphoric acid, or sulfuric acid, and combinations thereof. The liquid may be or include one or more solvents that are immiscible with the elastomer used (e.g., alcohols such as ethanol).Typically, the liquid is about 80% by weight to 100% by weight water, or 90% by weight to 99% by weight water based on the total weight of the liquid.

[0053] As an option for preparing a wet feedstock, the loading may be such that a dry feedstock is introduced into the mixer and moistened by adding the liquid (e.g., water, sequentially or simultaneously or nearly simultaneously) to form the wet feedstock in the mixer, and then the never-dried natural rubber may be added to the mixer. The introduction of a dry feedstock to be optionally moistened may be carried out with all or a portion of the feedstock intended for use.

[0054] Combining the never-dried natural rubber with a filler forms a mixture during the mixing step(s). The method further comprises, in one or more mixing steps, carrying out said mixture, wherein at least a portion of the water is removed by evaporation or an evaporation process that occurs during mixing. The water present in the never-dried natural rubber is capable of being removed by evaporation (and at least a portion is capable of being removed under the indicated mixing conditions). While other volatile substances may be present in never-dried natural rubber and may or may not evaporate during mixing, the volatile portion of a never-dried natural rubber is usually water or a major component of the volatile component is water. Thus, the overall volatile content has the boiling point of water or within a few degrees. Water in never-dried natural rubber can be distinguished from oils (e.g., extender oils, process oils, and resins) that may be present for at least part of the mixing, because such oils are intended to be present in the composite that is discharged and, therefore, do not evaporate for a significant portion of the mixing time.

[0055] With respect to mixing, mixing may be performed in one or more mixing steps. Mixing begins when at least the never-dried natural rubber and the filler are charged into the mixer, and power is applied to a mixing system that drives one or more rotors of the mixer. The one or more mixing steps may occur after the charging step is complete, or may overlap the charging step for any length of time. For example, a portion of the never-dried natural rubber and / or the filler may be charged into the mixer before or after mixing begins. The mixer may then be charged with one or more additional portions of the never-dried natural rubber and / or the filler. For batch mixing, the charging step is completed before the mixing step is completed.By "one or more mixing steps" it is intended that a first mixing step may comprise mixing at mixing temperatures controlled by at least one temperature control means, followed by additional mixing steps prior to discharge.

[0056] As indicated, during the one or more mixing steps disclosed herein, at least some water present in the mixture and / or the introduced never-dried natural rubber is removed at least in part by evaporation. As an option, the majority (by weight percent) of any water removed from the mixture occurs by evaporation. For example, at least 50% by weight of water is removed by evaporation, based on the total weight of water removed during mixing. The total weight of water removed can be determined from the difference between the water present in the never-dried natural rubber and any wet filler used, and any water remaining in the composite when it is discharged from the mixer plus any water present in, or drained from, the mixer when the composite is discharged from the mixer.For example, when the composite is discharged, any additional water (e.g., unevaporated water) may also be discharged, with or into the composite or through outlets provided in the mixer. Water removal by evaporation may be at least 30% by weight, at least 40% by weight, at least . less than 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or from 51% by weight to 100% by weight, from 51% by weight to 95% by weight, from 51% by weight to 90% by weight, from 51% by weight to 80% by weight, from 51% by weight to 70% by weight, from 60% by weight to 100% by weight, from 60% by weight to 95% by weight, from 60% by weight to 90% by weight, or from 60% by weight to 80% by weight of the total water contained in the never-dried natural rubber (and any optional wet filler) that is charged to the mixer.

[0057] As an option, the one or more mixing steps may further remove a portion of the liquid from the mixture by expressing, compacting and / or crushing, or any combination thereof. Alternatively, a portion of the liquid may be drained from the mixer after or while the composite is being discharged.

[0058] With respect to the mixer that may be used in any of the processes disclosed herein, any suitable mixer may be used that is capable of combining (e.g., blending or compositing) a filler with the wet natural rubber. The mixer(s) may be a batch mixer or a continuous mixer. A combination of mixers and processes may be used in any of the processes described herein, and the mixers may be used sequentially, in tandem, and / or integrated with other processing equipment. The mixer may be an internal or closed mixer or an open mixer, or an extruder or a continuous compounding device or a kneading mixer, or a combination thereof. The mixer may be capable of incorporating a filler into the natural rubber and / or capable of dispersing the filler throughout the natural rubber and / or distributing the filler throughout the natural rubber.Any or a combination of commercial mixers for producing rubber compounds may be used in the present processes.

[0059] The mixer may be capable of batch processing, continuous processing, or semi-continuous processing. The mixer may have any chamber capacity. An internal mixer typically includes a closed mixing chamber. For batch mixers, the chamber capacity may be at least 1 L, at least 2 L, at least 5 L, at least 10 L, at least 20 L, at least 50 L, at least 100 L, at least 250 L, at least 300 L, at least 600 L, or at least 1000 L, for example 1 L to 1500 L, 10 L to 1200 L, 10 L to 1000 L, 10 L to 750 L, 10 L to 500 L, 10 L to 300 L, 10 L to 100 L, 20 L to 1500 L, 20 L to 1200 L, 20 L to 1000 L, 20 L to 750 L, 20 L to 500 L, 20 L to 300 L, 20 L to 100 L, 50 L to 1500 L, 50 L to 1200 L, 50 L to 1000 L, 50 L to 750 L, 50 L to 500 L, 50 L to 300 L, or 50 L to 100 L.

[0060] The top of a typical batch mixing chamber may be raised and lowered by a pneumatic or hydraulic piston, commonly referred to as a "weight floating" or "plunger". The plunger operates in a housing known as a "feed hopper", which has a loading gate, through which the materials to be mixed are introduced. The plunger is raised to feed the materials (e.g., at least wet natural rubber and filler) and lowered to apply pressure to the mix and confine the mix in the mixing chamber. Typically, the batch fill rate and plunger pressure are selected so that the plunger can reach its lowest position to minimize clearance between the plunger and the rotors, which can allow for good filler dispersion. The vertical distance of the plunger above its minimum position is known as the "plunger deflection". The bottom of a typical batch mixer can be lowered on a pivot, and is known as the "drop gate".It is used to drain or "dump" the contents of the mixer.

[0061] The mixer may have one or more rotors (at least one rotor). For example, each rotor may rotate within its own cylindrical chamber, which may be connected to the chamber(s) of the other rotor(s). Typically, for a batch mixer, two rotors are used. The bodies of the one or more rotors are attached to shafts and may form a single component. The shafts are driven by a mixing system to which energy (electrical energy) is applied. A rotor may be considered a device that imparts energy to the mixture and / or to the components that form the mixture. The at least one rotor or the one or more rotors may be screw-type rotors, nested rotors, tangential rotors, mixing rotor(s), rotors used for extruders, a roller mill that imparts a large total specific energy, or a crepe roller mill.Typically, one or more rotors are used in the mixer, for example, the mixer may incorporate one rotor (e.g., a screw-type rotor), two, four, six, eight, or more rotors. Rotor assemblies may be positioned in parallel and / or in a sequential orientation in a given mixer configuration.

[0062] Water evaporating from the mixture may leave the mixer in one instance from a space between the plunger and the body and / or an orifice or outlet or vent designed to release evaporated water (e.g., water vapor). For example, in continuous mixers (such as devolatilizing extruders), evaporated water may be released through vent pushers or through a piston that periodically releases materials (e.g., evaporated water) through vents or outlets or orifices.

[0063] The process may use one or more mixing steps and / or one or more mixers. For example, a mixture of at least one never-dried natural rubber and the particulate filler to form a mixture, removal of at least a portion of the water from the mixture by evaporation, and removal from the mixture of the composite having a water content of not more than 5% by weight may occur as a mixing step in a mixer. In another example, a first mixing step comprises mixing the at least one never-dried natural rubber and the particulate filler to form a mixture, and the second mixing step comprises removal from the mixture of the composite having a water content of not more than 5% by weight. In this option, the first and second mixing steps may be carried out in the same mixers, or different mixers.In yet another example, mixing the at least one never-dried natural rubber and the particulate filler to form a blend, removing at least some of the water from the blend by evaporation, and removing from the blend the composite having a water content of no more than 5% by weight may occur as a first mixing step, and a second mixing step (in the same mixer or in a second mixer) may be performed to further dry the composite blend. In other words, the process may include using more than one mixer, such that the blend is mixed in a first mixer in a first mixing step, and then is subsequently removed and charged into a second mixer in a second mixing step, and so on as desired.Each mixer, if more than one is used, may be the same or different from the other mixers that are used in the process. For example, the composite may be discharged from a first mixer and otherwise transported to a second mixer. In another example, the composite may be discharged from one mixer and then charged back to the same mixer (e.g., after being allowed to cool). These processes, which may be known as multi-stage mixing, may be repeated as many times as necessary. Each stage may be mixed with the same or one or more different operating parameters.

[0064] In some embodiments, in at least one of said mixing steps, the method comprises performing said mixing at mixer temperatures controlled by at least one temperature control means. Control of mixer temperatures refers to control of temperatures of at least one surface of the mixer. As an option, mixer temperatures may be controlled both during loading and at least one of the mixing steps. The temperature control means may be a temperature control device on or in the mixer, or otherwise associated with the mixer (e.g., connected to the mixer) that heats or cools at least one surface, or one or more parts of the mixer.

[0065] The temperature control means may be, but is not limited to, the flow or circulation of a heat transfer stream through channels in one or more portions of the mixer. For example, the heat transfer stream may be water or a heat transfer oil. For example, the heat transfer fluid may flow through the rotors, the mixing chamber walls, the plunger, and the drop gate. In other embodiments, the heat transfer fluid may flow in a jacket (e.g., a jacket having fluid flow means) or coils around one or more portions of the mixer. As another option, the temperature control means (e.g., providing heat), may be electrical elements integrated into the mixer.The system for providing a temperature control means may further comprise means for measuring the temperature of the heat transfer fluid or the temperature of one or more portions of the mixer. The temperature measurements may be fed to systems used to control the heating and cooling of the heat transfer fluid. For example, the desired temperature of at least one surface of the mixer may be controlled by adjusting the temperature of the heat transfer fluid located in channels adjacent to one or more portions of the mixer, e.g., walls, doors, rotors, etc.

[0066] The temperature of the at least one temperature control means may be set and maintained, for example, by one or more control units ("TCUs"). In the case of a temperature control means incorporating heat transfer fluids, the temperature may be an indication of the temperature of the fluid itself.

[0067] The mixer may include thermocouples located at different parts of the mixer to provide a more accurate measurement of the temperature of the part(s) of the mixer or the mixture. The temperature of the at least one surface may differ from the temperature set in the TCU but should always be reasonably close to that temperature.

[0068] The mixer may have more than one temperature control means or device, such as two, three, or more, each of which provides a temperature control region within the mixer or a section of the mixer. The one or more temperature control means or devices may be located at any portion or part of the mixer(s). For example, one wall, walls, or all of the walls of the mixer or mixer chamber, and / or the plunger, and / or the chute gate(s), and / or the one or more rotors, and / or an extrusion head may have their temperature controlled to form one or multiple temperature control regions. As an option, the at least one means temperature control heats at least one wall of the mixer.

[0069] As an option, the TCU may be set to a temperature in the range of 5°C to 150°C, 30°C to 150°C, 40°C to 150°C, or 50°C to 150°C, for example, 40°C to 125°C, 50°C to 125°C, 40°C to 110°C, 50°C to 110°C, 50°C to 110°C, 65°C to 150°C, 65°C to 100°C, 70°C to 100°C, 75°C to 100°C, 50°C to 100°C, or 40°C to 100°C. Other beaches are possible with equipment available in the technique.

[0070] Compared to dry mixing, under similar situations of filler type, elastomer type, and mixer type, the present processes can allow for higher energy input. Controlled removal of water from the never-dried natural rubber allows for longer mixing times and therefore improves filler dispersion. As described herein, the present process provides operating conditions that balance longer mixing times with evaporation or removal of water within a reasonable amount of time.

[0071] Other operating parameters that need to be considered include the maximum pressure that can be used. The pressure affects the temperature of the filler and rubber mixture. If the mixer is a batch mixer with a plunger, the pressure inside the mixing chamber can be influenced by controlling the pressure applied to the plunger cylinder.

[0072] As an option, the process comprises, in at least one of the mixing steps, performing the mixing such that one or more rotors operate at a tip speed of at least 0.4 m / s for at least 50% of the mixing time. The energy input to the mixing system is a function, at least in part, of the speed of the at least one rotor and the rotor type. A tip speed, which takes into account a rotor diameter and a rotor speed, can be calculated according to the formula:

[0073] Top speed, m / s = ir x (rotor diameter, m) x (rotational speed, rpm) / 60.

[0074] As peak speeds may vary during mixing, as an option, the peak speed of at least 0.4 m / s, at least 0.5 m / s or at least 0.6 m / s is achieved for at least 50% of the mixing time, for example, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or substantially all of the mixing time. The tip speed may be at least 0.5 m / s, at least 0.6 m / s, at least 0.7 m / s, at least 0.8 m / s, at least 0.9 m / s, at least 1.0 m / s, at least 1.1 m / s, at least 1.2 m / s, at least 1.5 m / s, or at least 2 m / s for at least 50% of the mixing time, or other portions of the mixing listed above. The tip speeds may be selected to minimize mixing time, or may be 0.6 m / s to 10 m / s, 0.6 m / s to 8 m / s, 0.6 to 6 m / s, 0.6 m / s to 4 m / s, 0.6 m / s to 3 m / s, 0.6 m / s to 2 m / s, 0.7 m / s to 4 m / s, 0.7 m / s to 3 m / s, 0.7 m / s to 2 m / s, 0.7 m / s to 10 m / s, 0.7 m / s to 8 m / s, 0.7 to 6 m / s, 1 m / s to 10 m / s, 1 m / s to 8 m / s, 1 m / s to 6 m / s, 1 m / s to 4 m / s, 1 m / s to 3 m / s, or 1 m / s to 2 m / s, (for example, for at least 50% of the mixing time or other mixing times described herein). Alternatively or in addition, tip speeds may be selected to maximize throughput. Time / throughput considerations may take into account that as the mixing time decreases, the liquid level in the discharged composite may increase.In some situations, it may be beneficial to perform mixing at a high tip speed for higher efficiency balanced with the desired liquid content of the discharged composite (e.g., excessively high tip speeds may result in shorter residence or mixing times that do not allow for sufficient filler dispersion or liquid removal from the composite).

[0075] In all of the methods disclosed herein, the step of discharging from the mixer occurs and results in a composite comprising the filler dispersed in the natural rubber at a filler level of at least 20 phr, for example, 20 to 250 phr, or another filler level described herein. As an option, discharging occurs based on a defined mixing time. The mixing time between the start of mixing and discharging may be about 1 minute or more, such as about 1 minute to 40 minutes, about 1 minute to 30 minutes, about 1 minute to 20 minutes, or 1 minute to 15 minutes, or 3 minutes to 30 minutes, 5 minutes to 30 minutes, or 5 minutes to 20 minutes, or 5 minutes to 12 minutes, or 1 minute to 10 minutes, or 3 minutes to 10 minutes, or other times.Alternatively, for internal batch mixers, the plunger dwell time may be used as a parameter to monitor batch mixing times, e.g., the time during which the mixer is operated with the plunger in its lowest position, e.g., fully seated position or with plunger deformation as described herein. The plunger dwell time may be less than 30 min, less than 15 min, less than 10 min, in the range of 3 min to 30 min, 5 min to 15 min, or 5 min to 10 min. As an option, the discharge occurs based on a discharge or discharge temperature. For example, the mixer may have a discharge temperature in the range of 120°C to 190°C, 130°C to 180°C, such as 140°C to 180°C, 150°C to 180°C, 130°C to 170°C, 140°C to 170°C, 150°C to 170°C, or other temperatures within or outside these ranges.

[0076] The methods further include discharging from the mixer the composite that is formed. The discharged composite may have a water content of no more than 5% by weight based on the total weight of the composite, as outlined in Eq. next:

[0077] Water content of composite % = 100*[mass of water] / [mass of water + mass of dry composite]

[0078] In any of the methods disclosed herein, the discharged composite may have a water content of not more than 5% by weight based on the total weight of the composite (e.g., when the filler also includes water), not more than 3%, not more than 2%, or not more than 1% by weight based on the total weight of the composite. This amount may be in the range of 0.1% to 5%, 0.5% to 5%, 1% to 5%, 0.1% to 3%, 0.5% to 3%, or 1% to 3% by weight based on the total weight of the composite discharged from the mixer at the end of the process.

[0079] In any of the methods disclosed herein, the water content (moisture content) in the composite may be measured as a weight percent of water present in the composite based on the total weight of the composite. Any number of instruments known in the art for measuring water content in rubber materials, such as a colorimetric Karl Fisher® titration system, or a moisture balance, for example, from Mettler® (Toledo International, Inc., Columbus, OH). As explained herein, while the never-dried natural rubber may have water present, the filler used may also be a wet filler, and these other sources early in the process may provide or contribute to the amount of water in the mixture above the amount provided by the never-dried natural rubber alone.

[0080] In any of the methods described herein, while the discharged composite may have a water content of 5% by weight or less, there may optionally be water present in the mixer that is not contained in the composite being discharged. This excess water is not a part of the composite and is not a part of any water content calculated from the composite.

[0081] In any of the methods disclosed herein, the total water content of the material charged to the mixer is greater than the water content of the composite discharged at the end of the process. For example, the water content of the composite discharged may be less than the liquid content of the material charged to the mixer by an amount of 10% to 99.9% (weight percent vs. weight percent), 10% to 95%, or 10% to 50%).

[0082] In typical dry-mixing processes, one or more rubber chemicals (e.g., processing aids) are charged at the beginning of the mixing cycle to facilitate filler incorporation. Thus, rubber chemicals may be essential, but they may interfere with the bonding or interaction between the filler and elastomer surfaces and negatively impact the vulcanization properties. It has been found that the use of a rubber natural never dried allows mixing in the absence, or substantially in the absence, of such rubber chemicals.

[0083] Accordingly, as an option, any process disclosed herein may comprise charging a mixer with never-dried natural rubber and a filler and, in one or more mixing steps, mixing the never-dried natural rubber and the filler to form a blend in the substantial absence of rubber chemicals at mixer temperatures controlled by at least one temperature control means. Optionally, the process further comprises adding at least one additive selected from antidegradants and coupling agents during the charging or mixing, i.e., during the one or more mixing steps. Examples of such antidegradants (e.g., antioxidants) and coupling agents are described herein.As defined herein, the term "substantial absence" refers to a process in which the charging step and the one or more mixing steps may be carried out in the presence of the one or more rubber chemicals in an amount less than 10% by weight of the total amount of rubber chemicals ultimately provided in a vulcanizate prepared from the composite, e.g., the cured composite, or the charging step and the one or more mixing steps may be carried out in the presence of the one or more rubber chemicals in an amount less than 5% or less than 1% by weight of the total amount of rubber chemicals ultimately in the composite.Since it is optional to include the rubber chemicals in the composite, a suitable measure for determining the "substantial absence" of the one or more rubber chemicals is to determine the target amount in the vulcanizate prepared from the composite, e.g., after the composite has cured. Since it is optional to include the rubber chemicals in the composite, a suitable measure for determining the "substantial absence" of the one or more rubber chemicals is to determine the target amount in the vulcanizate prepared from the composite, e.g., after the composite has cured. Thus, a nominal amount of the one or more rubber chemicals may be added during said loading or mixing, but not an amount sufficient to interfere with the filler-elastomer interaction.As a further example of "substantial absence," the charging and mixing may be carried out in the presence of the one or more rubber chemicals in an amount or at a charging level of 5 phr or less, 4 phr or less, 3 phr or less, 2 phr or less, 1 phr or less, or 0.5 phr or less, 0.2 phr or less, 0.1 phr or less, relative to the resulting vulcanizate.

[0084] In any embodiment described herein, as an option, after the mixture of at minus the never-dried natural rubber and filler has begun and before the discharging step, the method may further comprise adding at least one antidegradant agent to the mixer such that the at least one antidegradant agent is mixed with the never-dried natural rubber and filler. The optional addition of the at least one antidegradant agent may occur at any time before the discharging step. For example, the addition of the at least one antidegradant agent may occur before the composite is formed and have a water content of 10% by weight or less, or 5% by weight or less. Examples of an antidegradant that may be introduced are N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and others are described in other sections herein. The antidegradant may be introduced in an amount in the range of 1% to 5%, 0.5% to 2%, or 0% to 3% based on the weight of the composite being formed.Antidegradants added during the loading step or the mixing step can help prevent elastomer degradation during mixing; however, due to the presence of water in the mix, the rate of elastomer degradation is slower compared to dry mixing processes, and the addition of antidegradant may be delayed.

[0085] After the composite has been formed and evacuated, the method may include the additional optional step of mixing the composite with an additional elastomer to form a composite comprising a blend of elastomers.The “supplemental elastomer” may be additional natural rubber or may be an elastomer that is not natural rubber such as functionalized natural rubber, synthetic elastomers (e.g., styrene-butadiene rubbers (SBR, such as solution SBR (SSBR), emulsion SBR (ESBR), or oil-diluted styrene-butadiene rubber (OESSBR)), polybutadiene (BR) and polyisoprene (IR) rubbers, functionalized polybutadiene rubber, ethylene-propylene rubber (e.g., EPDM), isobutylene-based elastomers (e.g., butyl rubber), polychloroprene rubber (CR), nitrile rubbers (NBR), hydrogenated nitrile rubbers (HNBR), polysulfide rubbers, polyacrylate elastomers, fluoroelastomers, perfluoroelastomers, and silicone elastomers).Other synthetic polymers include hydrogenated SBRs, and thermoplastic block copolymers (e.g., such as those that are recyclable). Synthetic polymers include copolymers of ethylene, propylene, styrene, butadiene, and isoprene. Other synthetic elastomers include those synthesized with metallocene chemistry in which the metal is selected from Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Tm, Yb, Lu, Co, Ni, and Ti. Polymers made from bio-based monomers may also be used, such as modern carbon-containing monomers as defined in the standard. ASTM D6866, for example, polymers made from bio-based styrene monomers described in U.S. Patent No. 9,868,853, or polymers based on bio-based monomers such as butadiene, isoprene, ethylene, propylene, farnesene, and comonomers thereof. Blends of two or more types of elastomers (mixtures of first and second elastomers), including blends of synthetic and natural rubbers or with two or more types of synthetic or natural rubber, may also be used.

[0086] The mixer may be charged with two or more charges of different elastomers to form a composite mixture. For example, the mixer may be charged with the never-dried natural rubber and at least one additional elastomer, where the at least one additional elastomer is also a coagulum or a solid elastomer (e.g., having less than 5% water). Alternatively, the mixer may be charged with a mixture of elastomers. As another option, the process may include mixing the discharged composite with an additional elastomer to form the mixture.The discharged composite (e.g., after one-stage, two-stage, or multi-stage mixing) may have a moisture content of not more than 5%, 3%, or 2% by weight based on the weight of the composite when mixed with one or more additional elastomers (e.g., a composite comprising carbon black and natural rubber may be mixed with synthetic elastomers such as BR or SBR). In addition, both elastomers and fillers (wet or dry, such as wet or dry carbon black and / or silica and / or silicon-treated carbon black) may be combined with the composite.

[0087] As another option, a composite comprising a filler (e.g., carbon black and / or silica) and natural rubber prepared according to the methods disclosed herein may be combined with a masterbatch containing natural rubber and / or synthetic polymers made by any method known in the art, such as by known dry-blending or solvent-masterbatching methods. For example, silica / elastomer masterbatches may be prepared as described in U.S. Patent Nos. 9,758,627 and 10,125,229, or neodymium-catalyzed polybutadienes masterbatches as described in U.S. Patent No. 9,758,646. The masterbatch may have a fibrous filler, such as poly(p-phenylene terephthalamide) pulp, as described in U.S. Patent No. 6,068,922. Other masterbatches include CNS masterbatches as described in U.S. Patent No. 9,447,259, and PCT Application No. PCT / US2021 / 027,814, and PCT Publication No.WO 2020 / 247663 (Composites / masterbatches prepared from the mixture of a wet filler and a solid elastomer). For example, the masterbatch may have a filler such as carbon black and / or silica and an elastomer such as SBR and / or butadiene rubber. Masterbatches . commercially available masterbatches may also be used, for example, commercially available masterbatches such as Emulsil™ / SBR silica masterbatch or Emulblack™ / SBR carbon black masterbatch (both available from the Dynasol Group).

[0088] Any of the methods described herein relate, in part, to methods of preparing a composite that involves at least two mixing steps or stages. These two (or more) mixing steps may be considered a multi-step or multi-stage mixing process with a first mixing step or stage, and at least one second mixing step or stage. One or more of the multi-stage mixing processes may be batch, continuous, semi-continuous, and combinations thereof.

[0089] For the multi-stage process, the methods for preparing the composite comprise the step of charging or introducing into a first mixer at least a) never-dried natural rubber and b) one or more fillers. The combination of the never-dried natural rubber with a filler forms a mixture or a composite during this or these mixing steps, which can be considered as a first step or a first mixing stage. The method further comprises mixing the mixture, during this first mixing step, to an extent such that at least some of the water is removed by evaporation or an evaporation process that occurs during mixing.This first step or stage of mixing is carried out using one or more of the processes described above, forming a composite with the understanding that, after completion of the first step or stage of mixing, it is not necessary for the mixture that is discharged from the mixer after the first mixing step (e.g., a discharged mixture) to have a water content of no more than 5% by weight. In other words, with the multi-stage process(es), the resulting mixture from the completion of the first mixture from the first mixer (or first mixing step) may have a water content greater than 5% by weight but has a water content that is reduced (in weight percent) compared to the water content of the combined never-dried natural rubber and filler at the start of the first mixing step.The method then comprises mixing or further mixing the mixture in at least one second or second mixing stage using the same mixer (i.e., the first mixer) or using one or more second mixers that are different from the first mixer. The method then comprises discharging from the final mixer used the composite that is formed, such that the composite has a water content of not more than 5% by weight based on the total weight of the composite.

[0090] In multi-stage processes, a second mixing stage (mixing of second stage) may include charging the mixer with other components in addition to the mixture discharged from the first mixing stage. For example, the method may include charging an additional filler, such as a dry filler, a wet filler (e.g., having a liquid present in an amount of at least 15% by weight), or a mixture thereof, before or during the second mixing stage. The additional filler may be the same as or different from the filler already present in the mixture, e.g., any of the additional fillers disclosed herein. For example, the mixture discharged from the first mixer may be considered a masterbatch in which all or a portion is combined with an additional filler.For example, wet or dry carbon black, silica, silicon-treated carbon black (and mixtures thereof) may be added to the mixture discharged from the first mixing stage, such as a mixture comprising carbon black and natural rubber.

[0091] For example, the first mixer may be a tangential mixer or a nested mixer, and the second mixer may be a tangential mixer, a nested mixer, an extruder, a kneader, or a roller mill.

[0092] For example, the first mixer may be an internal mixer, and the second mixer may be a kneader, a single screw extruder, a twin screw extruder, a multi-screw extruder, a continuous combining device, or a roller mill.

[0093] For example, the first mixer may be a first tangential mixer, and the second mixer may be a second (different) tangential mixer.

[0094] For example, the first mixer is operated with a plunger, and the second mixer is operated without a plunger.

[0095] In any of the multi-stage processes described herein, the final discharged composite (e.g., the composite discharged after the second or third or greater mixing stage) may have a water content of 5 wt% or less, such as 5 wt% or less, or 2 wt% or less, or 1 wt% or less, based on the total weight of the composite. This amount may be from about 0.1 wt% to 10 wt% or from about 0.5 wt% to 9 wt% or from about 0.5 wt% to 7 wt%, based on the total weight of composite discharged from the mixer at the end of the process.

[0096] In any of the multi-stage processes described herein, the total water content of the material charged to the mixer at the beginning of the process is greater than the water content of the composite when the first mixing stage is stopped. For example, the water content of the mixture when the first mixing stage is stopped may be 10% to 50% lower (weight percent vs. weight percent) or may be 25% or lower, or 10% lower than at the start of the first mixing stage.

[0097] Additionally, in the multi-stage processes described herein, the total water content of the mixture at the end of the first mixing stage is greater than the water content of the final composite discharged at the end of the process (after the last mixing stage). For example, the water content of the discharged composite may be 10% to 50% lower (weight percent vs. weight percent) or may be 25% or lower, or 10% or lower than after the end of the first mixing stage.

[0098] In any of the multi-stage processes described herein, after discharge from the last mixer, the temperature (e.g., pour temperature) of the composite may be in a range of 130°C to 180°C, such as 140°C to 170°C. Alternatively, the multi-stage process may be monitored by a material temperature, or probe temperature, which is the temperature of the composite mixture taken or measured immediately after discharge (less than 5 min after, less than 3 min after, or less than 60 seconds after), and may be considered an average temperature of the composite material.

[0099] As an option, any of the methods described herein lend themselves to implementation as a unit operation in a multi-unit manufacturing facility, such as a natural rubber manufacturing / processing facility in combination with a rubber composite or a rubber vulcanization facility. For example, the multi-unit manufacturing facility may include a receiving portion for receiving latex from tanks loaded onto trucks or other vehicles, where this latex is transferred or discharged into troughs (e.g., a series or lines of troughs) (or similar channels or holding devices). In these troughs, the latex may be treated so as to coagulate the latex and thereby become a coagulum, for example, by adding an acid or salt to the latex.Once coagulated, the coagulum may optionally be subjected to dehydration steps (e.g., pressing the coagulum with one or more rollers) or the dehydration steps may be skipped, and the coagulum may be transferred to the area of ​​the multi-unit manufacturing facility that processes the starting natural rubber into a rubber composite and, ultimately, a vulcanized rubber composite, including mixers, and all post-processing steps.

[0100] It may be beneficial to use never-dried natural rubber in the integrated manufacturing option to improve filler incorporation and dispersion and to avoid or reduce the usual natural rubber drying processes. Advantages of such a multi-unit manufacturing operation include those listed herein, together with obtaining a superior composite quality, a customized and simplified manufacturing process for producing composites from of never-dried natural rubber, and significant energy and cost savings.

[0101] Since the integrated manufacturing process can use wet natural rubber, the ability to use never-dried natural rubber can potentially create a more efficient operation and can enable a turnkey type of operation. The use of any never-dried natural rubber is possible in such integrated processes as described herein.

[0102] The composite may be used to produce products containing natural rubber. As an option, the elastomeric composite may be used or produced for use, for example, to form a vulcanizate for incorporation into various parts of a tire, for example, tire treads, including a cap and base, an undertread, inner rubbers, tire sidewalls, tire casings, tire sidewall inserts, a cord skin for tires, and a cushion rubber for retreaded tires, in pneumatic tires as well as non-pneumatic tires or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, caulks, wiper blades, automotive components, liners, pads, housings, pad and wheel members,tire sidewall inserts, tire cord skins, cushion rubber for retreaded tires, in pneumatic tires as well as non-pneumatic tires or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, seals, wiper blades, automotive components, liners, pads, housings, pad and wheel elements, tire sidewall inserts, tire cord skins, cushion rubber for retreaded tires, in pneumatic tires as well as non-pneumatic tires or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, anti-vibration articles, tracks, track pads for tracked vehicle equipment,engine mounts, seismic stabilizers, mining equipment such as screens, mining equipment packings, conveyor belts, chute liners, slurry pump liners, slurry pump components such as impellers, valve seats, valve bodies, piston hubs, piston rods, plungers, impellers for various applications such as mixing slurries and slurry pump impellers, mill liners, cyclones and hydrocyclones, expansion joints, marine equipment such as pump packings (e.g., dredge pumps and outboard motor pumps), hoses (e.g., dredge hoses and , outboard motor) and other marine equipment, shaft seals for marine, petroleum, aerospace and other applications, propeller shafts, pipeline packings for transporting, for example, oil sands and / or tar sands, and other applications where improved abrasion resistance and / or dynamic properties are desired. In addition, the elastomeric composite, via the vulcanized elastomeric composite, can be used in cylinders, cams, shafts, hoses, vehicle bearings, or in other applications where improved abrasion resistance and / or dynamic properties are desired.

[0103] The filler (e.g., wet or dry or both) that is used in the methods described herein may be a solid material, e.g., a solid bulk material, in the form of a powder, paste, pellet, or cake. In the methods, the filler may be dispersed in the natural rubber at a filler level in the range of 20 phr to 100 phr on a dry weight basis, or a filler level in the range of 20 phr to 250 phr, 20 phr to 200 phr, e.g., 20 phr to 180 phr, 20 phr to 150 phr, 20 phr to 120 phr, or 20 phr to 100 phr, as well as other ranges described herein.

[0104] The filler in general may be any usual filler used with elastomers such as reinforcing fillers including, but not limited to, carbon black, silica, a filler comprising carbon black, a filler comprising silica, and / or any combinations thereof. The filler may be particulate or fibrous or plate-like. For example, a particulate filler is comprised of discrete bodies. Such fillers may often have an aspect ratio (e.g., length to diameter) of 3:1 or less, or 2:1 or less, or 1.5:1 or less. Fibrous fillers may have an aspect ratio of, for example, 2:1 or greater, 3:1 or greater, 4:1 or greater, or higher. Typically, fillers used to reinforce elastomers have dimensions that are microscopic (e.g., hundreds of microns or less) or nanoscalar (e.g., less than 1 micron).In the case of carbon black, discrete bodies of particulate carbon black refer to the aggregates or agglomerates formed from primary particles, and not the primary particles themselves. In other embodiments, the filler may have a plate-like structure, such as graphenes and reduced graphene oxides.

[0105] The feedstock may comprise at least one material that is selected from carbonaceous materials, carbon black, silica, nano-cellulose, lignin, clays, nano-clays, metal oxides, metal carbonates, pyrolysis carbon, recycled carbon, reclaimed carbon black (e.g., as defined in ASTM-D8178-19, rCB), graphenes, graphene oxides, reduced graphene oxide (e.g., reduced graphene oxide augers as described in PCT Publication No. WO 2019 / 070514A1, or densified reduced graphene oxide granules as described in US Provisional Application No. 62 / 857,296, filed June 5, 2019, and PCT Publication No. 2020 / 247681 filed June 5, 2019), carbon nanotubes, single-walled carbon nanotubes, multi-walled carbon nanotubes, or combinations thereof, or coated materials thereof or chemically treated materials thereof (e.g., chemically treated carbon black). Other suitable fillers include carbon nanostructures (CNSs, singular CNS), a plurality of carbon nanotubes (CNTs) that are crosslinked into a polymer structure by being branched, e.g., dendrimerically, interdigitated, entangled, and / or sharing common walls with each other. CNS fillers are described in U.S. Patent No. 9,447,259, and PCT Application No. PCT / US2021 / 027,814.The filler may be chemically treated (e.g., chemically treated carbon black, chemically treated silica, silicon-treated carbon black) and / or chemically modified. The filler may be or include carbon black having organic group(s) attached. The filler may have one or more coatings present in the filler (e.g., silicon-coated materials, silica-coated material, carbon-coated material). The filler may be oxidized and / or have other surface treatments. There is no limit to the type of filler (e.g., silica, carbon black, or other fillers) that may be used. More details regarding the filler are provided here in other sections.

[0106] As mentioned previously, fibrous fillers may also be incorporated into the methods described herein, including natural fibers, semi-synthetic fibers, and / or synthetic fibers (e.g., nano-sized carbon filaments), such as those described in PCT Publication No. WO 2021 / 153643. Other fibrous fillers include poly(p-phenylene terephthalamide) pulp, commercially available as Kevlar® pulp (Du Pont).

[0107] Other suitable fillers include bio-based or bio-based materials (derived from biological sources), recycled materials, or other fillers considered renewable or sustainable include hydrothermal carbon (HTC), where the filler comprises lignin that has been treated by hydrothermal carbonization as described in U.S. Patent Nos. 10,035,957 and 10,428,218), rice hull silica, carbon from methane pyrolysis, modified polysaccharide particles, starch, siliceous earth, powdered rubber, and functionalized crumb rubber. Examples of modified polysaccharides include those described in patent publications US Nos. 2020 / 0 181 370 and 2020 / 0 190 270. For example, the polysaccharides may be selected from: poly alpha-1,3-glucan; poly alpha-1,3-1,6-glucan; a water-insoluble alpha(1,3-glucan) polymer having 90% or more α-1,3-glycosidic linkages, less than 1% by weight of alpha-1,3,6-glycosidic branch points, and a number average degree of polymerization in the range of 55 to 10,000; dextran; a composition comprising a poly alpha-1,3-glucan ester compound; and water-insoluble cellulose having a weight average degree of polymerization (DPw) of about 10 to about 1,000 and a cellulose II crystal structure.

[0108] The filler may be or include a mixture of carbon black and silica in any weight ratio, such as a weight ratio in the range of 1:99 to 99:1 or 25:75 to 75:25 or 45:55 to 55:45. As an option, a mixture of carbon black and silica may contain at least 1% carbon black (i.e., not more than 99% silica), at least 5% carbon black, at least 10% carbon black, at least 20% carbon black, at least 30% carbon black, at least 50% carbon black, at least 75% carbon black, at least 90% carbon black, at least 95% carbon black, or at least 99% carbon black (i.e., not more than 1% silica).

[0109] The amount of filler that is charged into the mixture may be in the range of 20 phr to 250 phr, 20 phr to 200 phr, 20 phr to 150 phr, 20 phr to 100 phr, 30 phr to 100 phr, 40 phr to 100 phr, 50 phr to 100 phr, 20 phr to 70 phr, 30 phr to 70 phr, 35 phr to 70 phr, 40 phr to 70 phr, 20 phr to 65 phr, 30 phr to 65 phr, 35 phr to 65 phr, 40 phr to 65 phr, 20 phr to 60 phr, 30 phr to 60 phr, 35 phr to 60 phr, 40 phr to 60 phr, 20 phr to 50 phr, or other amounts within or outside one or more of these ranges. The filler may be any filler described herein, such as carbon black, silica, or silicon-treated carbon black, alone or with one or more other fillers.

[0110] As an example, the carbon black may be dispersed in the natural rubber at a loading level in the range of 30 phr to 70 phr, or 40 phr to 65 phr, or 40 phr to 60 phr. As a more specific example, with the elastomer being natural rubber alone or with one or more other elastomers, and the filler being carbon black alone or with one or more other fillers (e.g., silica or silicon-treated carbon black), the carbon black may be dispersed in the natural rubber at a loading level in the range of 30 phr to 70 phr, or 40 phr to 65 phr, or 40 phr to 60 phr.

[0111] For graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-walled carbon nanotubes, multi-walled carbon nanotubes, these fillers can be dispersed in the elastomer at a filler level in the range of 1 phr to 100 phr, for example, 1 phr to 50 phr, 1 phr to 25 phr, 1 phr to 20 phr, or 1 phr to 10 phr. When combined with other fillers, such as carbon black, the graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-walled carbon nanotubes, and multi-walled carbon nanotubes may be dispersed in the elastomer at a filler level in the range of 0.5 phr to 99 phr, for example, 0.5 phr to 50 phr, 0.5 phr to 25 phr, 0.5 phr to 20 phr, or 0.5 phr to 10 phr.In such combinations, the graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-walled carbon nanotubes, and multi-walled carbon nanotubes may be present in an amount of at least 1%, at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, at least 30%, at least 40%, or at least 50% by weight of the total amount of filler dispersed in the elastomer.

[0112] The carbon black may be untreated carbon black or treated carbon black or a mixture thereof. The feedstock may be or include carbon black in the form of pellets, flake powder, granules, and / or agglomerates. Wet carbon black may be formed into pellets, granules, or agglomerates, for example, in a pelletizing device, a fluidized bed, or other equipment for making the wet feedstock.

[0113] The carbon black used in any of the processes described herein may be any grade of reinforcing carbon blacks or semi-reinforcing carbon blacks. Examples of ASTM standard reinforcing grades are carbon blacks NI 10, N121, N134, N220, N231, N234, N299, N326, N330, N339, N347, N351, N358 and N375. Examples of ASTM standard semi-reinforcing grades are carbon blacks N539, N550, N650, N660, N683, N762, N765, N774, N787, N990 and / or the N990 grade of thermal blacks.

[0114] The carbon black may have any statistical surface area per thickness (STSA) such as in the range of 20 m2 / g to 250 m2 / g or more. The STSA (thickness statistical surface area) is determined based on ASTM D-5816 test procedure (measured by nitrogen adsorption). The carbon black may have a compressed oil absorption (COAN) number of from about 30 mL / 100 g to about 150 mL / 100 g. The compressed oil absorption (COAN) number is determined in accordance with ASTM D3493. As an option, the carbon black can have an STSA in the range of 20 m2 / g to 180 m2 / g, or 60 m2 / g to 150 m2 / g with a COAN in the range of 40 mL / 100 g to 115 mL / 100 g or 70 mL / 100 g to 115 mL / 100 g.

[0115] As stated, the carbon black may be a rubber black, and in particular a reinforcing grade of carbon black or a semi-reinforcing grade of carbon black. Carbon blacks sold under the Regai®, Black Pearls®, Spheron®, Sterling®, Propel®, Endure™ and Vulcan® brands available from Cabot Corporation, the Raven®, Statex®, Furnex® and Neotex® brands and the CD and HV lines available from Birla Carbon (formerly available from Columbian Chemicals), and the registered trademarks Corax®, Durax®, Ecorax® and Purex® and the CK line available from Orion Engineered Carbons (formerly Evonik and Degussa Industries), and other fillers suitable for use in rubber or tire applications, may also be exploited for use with various implementations. Suitable chemically functionalized carbon blacks include those described in WO 96 / 18688 and US 2013 / 0165560. Mixtures of any of these carbon blacks may be employed.Carbon blacks having surface areas and structures beyond the ASTM grades and typical values ​​chosen for blending with rubber may be used, such as those described in US Publication No. 2018 / 0282523.

[0116] The carbon black may be an oxidized carbon black, such as a carbon black that has been surface-treated with an oxidizing agent. Oxidizing agents include, but are not limited to, air, oxygen gas, ozone, NO2 (including mixtures of NO2 and air), peroxides such as hydrogen peroxide, persulfates, including sodium, potassium or ammonium persulfate, hypohalites such as sodium hypochlorite, halites, halates or perhalates (such as sodium chlorite, sodium chlorate or sodium perchlorate), oxidizing acids such as nitric acid and transition metal containing oxidants such as permanganate salts, osmium tetroxide, chromium oxides or ceric ammonium nitrate.Oxidizing agents include, but are not limited to, air, oxygen gas, ozone, NO2 (including mixtures of NO2 and air), peroxides such as hydrogen peroxide, persulfates, including sodium, potassium or ammonium persulfate, hypohalites such as sodium hypochlorite, halites, halates or perhalates (such as sodium chlorite, sodium chlorate or sodium perchlorate), oxidizing acids such as nitric acid and transition metal containing oxidants such as permanganate salts, osmium tetroxide, chromium oxides or ceric ammonium nitrate. Mixtures of oxidants may be used, particularly mixtures of gaseous oxidants such as oxygen and ozone.Additionally, carbon blacks prepared using other surface modification processes to introduce ionic or ionizable groups onto a pigment surface, such as chlorination and sulfonation, may also be used. Processes that can be used to generate oxidized carbon blacks are known in the art and . Several types of oxidized carbon black are commercially available.

[0117] The carbon black may be a furnace black, a gas black, a thermal black, an acetylene black or a lamp black, a plasma black, a reclaimed carbon black (e.g., as defined in ASTM D8178-19), or a carbon product containing silicon-containing species, and / or metal-containing species, and the like. The carbon black may be a multi-phase aggregate comprising at least one carbon phase and at least one metal-containing species phase or silicon-containing species phase, i.e., silicon-treated carbon black. In silicon-treated carbon black, a silicon-containing species, such as a silicon oxide or carbide, is distributed throughout at least a portion of the carbon black aggregate as an intrinsic part of the carbon black.Silicon-treated carbon blacks are not carbon black aggregates that have been coated or otherwise modified, but actually represent two-phase aggregate particles. One phase is carbon, which will always be present as graphitic crystallite and / or amorphous carbon, while the second phase is silica, and optionally other silicon-containing species. Thus, the silicon-containing species phase of the silicon-treated carbon black is an intrinsic part of the aggregate, distributed throughout at least a portion of the aggregate. Ecoblack™ silicon-treated carbon blacks are available from Cabot Corporation. The manufacture and properties of these silicon-treated carbon blacks are described in U.S. Patent No. 6,028,137.

[0118] The silicon-treated carbon black may include silicon-containing regions primarily at the surface of the carbon black aggregate, but still be part of the carbon black and / or the silicon-treated carbon black may include silicon-containing regions distributed throughout the carbon black aggregate. The silicon-treated carbon black may be oxidized. The silicon-treated carbon black may contain from about 0.1% to about 50% silicon by weight, for example, from about 0.1% to about 46.6%, from about 0.1% to about 46%, from about 0.1% to about 45%, from about 0.1% to about 40%, from about 0.1% to about 35%, from about 0.1% to about 30%, from about 0.1% to about 25%, from about 0.1% to about 20%, from about 0.1% to about 15%, from about 0.1% to about 10%, from about 0.1% to about 5%, or from about 0.1% to about 2% by weight, based on the weight of the silicon-treated carbon black.These amounts may be from about 0.5 wt% to about 25 wt%, from about 1 wt% to about 15 wt% of silicon, from about 2 wt% to about 10 wt%, from about 3 wt% to about 8 wt%, from about 4 wt% to about 5 wt% or about 6 wt%, all based on the weight of the silicon-treated carbon black. The amount of silicon-treated carbon black present in the composite. elastomer can be 20 phr to 250 phr, 20 phr to 200 phr, 30 phr to 150 phr, 40 phr to 100 phr, or 50 phr to 65 phr.

[0119] Those skilled in the art will recognize that, separate from the silicon content of the silicon-treated carbon black, the surface area of ​​the particle may also have varying amounts of silica and carbon black. For example, the surface area of ​​the silicon-treated carbon black may comprise from about 5% to about 95% silica, e.g., from about 10% to about 90%, from about 15% to about 80%, from about 20% to about 70%, from about 25% to about 60%, from about 30% to about 50%, or from about 35% to about 40%, e.g., up to about 20% or up to about 30% silica. The amount of silica at the surface can be determined by the difference between the surface areas of the particles as measured by iodine number (ASTM D-1510) and nitrogen adsorption (i.e., BET, ASTM D6556).

[0120] As another option, the filler, e.g., carbon black, may be chemically treated. For example, the carbon black may have at least one organic group attached. The attachment may occur via a diazonium reaction where the at least one organic group has a diazonium salt substituent as detailed, e.g., in U.S. Patent Nos. 5,554,739; 5,630,868; 5,672,198; 5,707,432; 5,851,280; 5,885,335; 5,895,522; 5,900,029; 5,922,118.

[0121] With respect to the filler, as an option, being at least silica, it is possible to use one or more types of silica, or any combination of silica(s), in any embodiment described herein. With respect to the filler, as an option, being at least silica, it is possible to use one or more types of silica, or any combination of silica(s), in any embodiment described herein. The silica may comprise or be precipitated silica, fumed silica, silica gel and / or colloidal silica. The silica may be or comprise untreated silica and / or chemically treated silica.Silica may be suitable for reinforcement of elastomeric composites and may be characterized by a Brunaur Emmett Teller (BET, as determined by multipoint BET nitrogen adsorption, ASTM D1993) surface area of ​​about 20 m2 / g to about 450 m2 / g; about 30 m2 / g to about 450 m2 / g; about 30 m2 / g to about 400 m2 / g; or from about 60 m2 / g to about 250 m2 / g, from about 60 m2 / g to about 250 m2 / g, from about 80 m2 / g to about 200 m2 / g.The silica may be suitable for reinforcement of elastomeric composites and may be characterized by a Brunaur Emmett Teller (BET, as determined by multipoint BET nitrogen adsorption, ASTM D1993) surface area of ​​from about 20 m2 / g to about 450 m2 / g; from about 30 m2 / g to about 450 m2 / g; from about 30 m2 / g to about 400 m2 / g; or from about 60 m2 / g to about 250 m2 / g, from about 60 m2 / g to about 250 m2 / g, from about 80 m2 / g to about . 200 m2 / g. The silica may have an STSA ranging from about 80 m2 / g to 250 m2 / g, such as from about 80 m2 / g to 200 m2 / g or from 90 m2 / g to 200 m2 / g, from 80 m2 / g to 175 m2 / g, or from 80 m2 / g to 150 m2 / g. The silica may have an STSA ranging from about 80 m2 / g to 250 m2 / g, such as from about 80 m2 / g to 200 m2 / g or from 90 m2 / g to 200 m2 / g, from 80 m2 / g to 175 m2 / g, or from 80 m2 / g to 150 m2 / g. Highly dispersible precipitated silica may be used as a filler in the present methods. Highly dispersible precipitated silica (“HDS”) means any silica having a substantial ability to deagglomerate and disperse in an elastomeric matrix. Such dispersion determinations can be observed in a known manner by electron or optical microscopy on thin sections of elastomeric composite.Examples of commercial grades of HDS include Perkasil® GT 3000GRAN silica from WR Grâce & Co, Ultrasil® 7000 silica from Evonik Industries, Zeosil® 1165 MP, 1115 MP, Premium, and 1200 MP silicas from Solvay SA, Hi-Sil® EZ 160G silica from PPG Industries, Inc., and Zeopol® 8741 or 8745 silica from Evonik Industries. Conventional non-HDS precipitated silica may also be used. Examples of commercial grades of conventional precipitated silica include Perkasil® KS 408 silica from WR Grâce & Co, Zeosil® 175GR silica from Solvay SA, Ultrasil® VN3 silica from Evonik Industries, and Hi-Sil® 243 silica from PPG Industries, Inc. Precipitated silica with surface-attached silane coupling agents can also be used. Examples of commercial grades of chemically treated precipitated silica include Agilon® 400, 454, or 458 silica from PPG Industries, Inc., and Coupsil® silicas from Evonik Industries, for example Coupsil® 6109 silica. .

[0122] Any of the silica(s) may be chemically functionalized, such as to have attached or adsorbed chemical groups, such as attached or adsorbed organic groups. Any combination of silica(s) may be used. The silica may be in part or entirely a silica having a hydrophobic surface, which may be a hydrophobic silica or a silica becoming hydrophobic by rendering the surface of the silica hydrophobic by treatment (e.g., chemical treatment). The hydrophobic surface may be obtained by chemically modifying the silica particle with hydrophobizing silanes without an ionic group, e.g., bis-triethoxysilylpropyltetrasulfide. Suitable surface-treated hydrophobic silica particles for use herein may be obtained from commercial sources, such as Agilon® 454 silica and Agilon® 400 silica, from PPG Industries.Silica having a low surface silanol density, for example, silica obtained by dehydroxylation at temperatures above 150°C via, for example, a calcination process, may be used herein. An intermediate form of silica obtained from a precipitation process in tablet or . Paste, without drying (a silica that has never been dried) can be added directly to a mixer as a wet feedstock, thus eliminating complex drying and other downstream processing steps used in the typical manufacture of precipitated silicas.

[0123] In any embodiment and in any step, a coupling agent may be introduced in any of the steps (or in multiple steps or locations) as long as the coupling agent has an opportunity to be dispersed in the composite. The coupling agent may be or comprise 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 may be or include 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-thiocyanatopropyl-triethoxysilane (e.g., Si 264® from Evonik Industries), gamma-mercaptopropyl-trimethoxysilane (e.g., VP Si 163® from Evonik Industries, Struktol® SCA989 from Struktol Company), gamma-mercaptopropyl-triethoxysilane (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)octanethioate (e.g., NXT® coupling agent from Momentive, Friendly, WV), and / or coupling agents that are chemically similar or have the same one or more chemical groups.Additional specific examples of coupling agents, by trade names, include, but are not limited to, VP Si 363® from Evonik Industries, and NXT Z® and NXT Z-50® silanes from Momentive. Other compounds that may function as coupling agents include those compounds having a nitroxide radical, e.g., TEMPO (2,2,6,6-tetramethyl-l-piperidinyloxy radical), as described in U.S. Patent Nos. 6,084,015, 6,194,509, 8,584,725, and US Publication 2009 / 0292044, or 1,3-dipolar compounds of nitrile oxide, nitrile imine, and nitrone, as disclosed in U.S. Patent Nos. 10,239,971, 10,202,471, 10,787,471 and US Publication No. 2020 / 0362139. The coupling agents described herein could be used to provide hydrophobic surface modification of silica (precoupled or pretreated silica) prior to use in any of the processes described herein.It should be noted that any combination of elastomers, additives and additional composite can be added to the elastomeric composite, for example in a compounding device.

[0124] As another option, mixing (e.g., where the filler includes silica and / or silicon-treated carbon black) can be made without coupling agents.

[0125] The amount of silica (in parts per hundred of rubber, or phr) present in the formed elastomeric composite may be 20 phr to 250 phr, 20 phr to 200 phr, 20 phr to 150 phr, 20 phr to 100 phr, 30 phr to 150 phr, 30 phr to 100 phr, 25 phr to 100 phr, 25 phr to 80 phr, 35 phr to 115 phr, 35 phr to 100 phr, 40 phr to 110 phr, 40 phr to 100 phr, 40 phr to 90 phr, 40 phr to 80 phr, and the like. Filler mixtures comprising silica may comprise 10% by weight of carbon black and / or silicon-treated carbon black.

[0126] If a wet feedstock is selected, a wet feedstock that can be used in the processes herein, such as carbon black, wet silica, or wet silicon-treated carbon black (described in more detail herein), can be described with respect to a liquid content determined by its oil absorption number (OAN). A wet filler such as wet carbon black may be used herein according to the equation: k* OAN / ( 100+OAN) * 100, wherein k is in the range of 0.3 to 1.1, or 0.5 to 1.05, or 0.6 to 1.1, or 0.7 to 1.1, or 0.8 to 1.1, or 0.9 to 1.1, or 0.6 to 1.0, or 0.7 to 1.0, or 0.8 to 1.0, or 0.8 to 1.05, or 0.9 to 1.0, or 0.95 to 1, or 0.95 to 1.1, or 1.0 to 1.1.

[0127] As a more specific example, if selected, such a wet filler having this type of "wet" form as a solid may contain, for example, up to 80% by weight of liquid (e.g., water and / or other aqueous liquid) based on the total weight of the wet filler. The wet filler may have a liquid content (e.g., water content) of 80% by weight or less, such as 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, such as from about 15% to about 80%, from about 20% by weight to about 80%, from about 25% to about 80%, from about 30% to about 80%, from about 35% to about 80%, from about 40% to about 80%, from about 15% by weight to about 70%, from about 20% by weight to about 70%, from about 25% by weight to 70%, from about 30% to 70%, from about 35% to about 70%, from about 40% to 70%, from about 15% by weight to about 65%, from about 20% to about 65% by weight, from about 25% to about 65% by weight, from about 30% to about 65% by weight, from about 35% to about 65% by weight, from about 40% to about 65% by weight, from about 15% to about 60%, from about 20% to about 60% by weight, from about 25% by weight to about 60% by weight, from about 30% by weight to about 60% by weight, from about 35% by weight to about 60% by weight, from about 40% by weight to 60% by weight, or any other range from these various values ​​given herein.

[0128] As a more specific example, a wet carbon black may have a liquid content in the range of about 20% to about 70% by weight, based on the total weight wet carbon black, for example from about 25% to about 70%, from about 30% to about 70%, from about 35% to about 70%, from about 40% to about 70%, from about 45% to about 70%, from about 50% to about 70%, from about 20% to about 65% by weight.

[0129] While the amount of liquid in the filler as described above may also apply to silica, as a more particular example, when silica is used as the wet filler (if this option is used) in part or in whole as the wet filler, the silica may have liquid present in an amount of from about 25% by weight to about 75% by weight, for example from about 30% to about 75%, from about 40% to about 75%, from about 45% to about 75%, from about 50% to about 75%, from about 30% to about 70%, from about 40% to about 70%, from about 45% to about 70%, from about 50% to about 70%, from about 30% to about 65%, from about 40% to about 65%, from about 45% to about 65%, 50% to about 65%, from about 30% to about 60% by weight, from about 40% to about 60%, from about 45% to about 60%, or from about 50% to about 60%,based on the weight of the total wet charge or based on the weight of only the wet silica present.

[0130] The wet carbon black, if used, may be one or more of the following:

[0131] never-dried carbon black; and / or

[0132] pellets of never-dried carbon black; and / or

[0133] dried carbon black pellets that have been rewetted, such as with water in a pelletizing device; and / or

[0134] carbon black pellets which have been ground and then re-wetted with water in a pelletizing device; and / or

[0135] dried carbon black pellets combined with water; and / or

[0136] flake powder, granules, or agglomerates combined with water.

[0137] Composites prepared by any of the methods described herein may be composed of natural rubber and filler, i.e., no rubber chemicals are present. Alternatively, in addition to the filler and natural rubber, the composite may include at least one additive selected from antidegradants and coupling agents. Alternatively, the composites may include one or more rubber chemicals. In another alternative, the composite may be compositions carrying curing agents.

[0138] It is often necessary to add certain additives to elastomeric composites; typical additives include antidegradants, coupling agents, and one or more rubber chemicals to enable filler dispersion in the elastomer. Rubber chemicals, as defined herein, include take one or more of: processing aids (to facilitate the mixing and processing of rubber, e.g., various oils and plasticizers, wax), activators (to activate the vulcanization process, e.g., zinc oxide and fatty acids), accelerators (to accelerate the vulcanization process, e.g., sulfenamides and thiazoles), vulcanizing agents (or hardeners, to crosslink rubbers, e.g., sulfur, peroxides), and other rubber additives, such as, but not limited to, retarders, coagents, peptizers, adhesion promoters (e.g., the use of cobalt salts to promote adhesion to rubber-based elastomers (e.g., as described in U.S. Pat. No. 5,221,559 and U.S. Pat. No.2020 / 0 361 242), resins (e.g., tackifiers, tensile resins), flame retardants, colorants, blowing agents and additives to reduce heat buildup (HBU), and bonding agents such as those described in US Provisional Application No. WO 63 / 123 386. As an option, the rubber chemicals may include processing aids and activators. As another option, the one or more other rubber chemicals are selected from zinc oxide, fatty acids, zinc salts of fatty acids, wax, accelerators, resins, and processing oil.Exemplary resins include those selected from one or more of C5 resins, C5-C9 resins, C9 resins, rosin resins, terpene resins, aromatic-modified terpene resins, dicyclopentadiene resins, alkylphenol resins, and the resins described in U.S. Patent Nos. 10,738,178, 10,745,545 and U.S. Patent Publication No. 2015 / 0283854.

[0139] At least one additive may be included during the mixing process described herein or may be included after the composite is formed. The at least one additive may include a curing condition or at least one curing agent. To create a vulcanizable composite, the added curing condition may include a crosslinking agent and any activators and accelerators. When sulfur is used as the crosslinking agent, typical activators include zinc oxide and / or stearic acid, and typical accelerators include sulfenamides such as N-tert-butyl-2-benzothiazole sulfenamide (TBBS) and N-cyclohexyl-2-benzothiazole sulfenamide (CBS). Other curing agents used in rubber processing are peroxides, urethane crosslinkers, metal oxides, acetoxysilane compounds, phenolic resins, and so on.Additional components suitable for sulfur-based and other crosslinking systems are well known to those skilled in the art.

[0140] Other rubber chemicals include antioxidants, processing aids, extender oils, wax, a variety of resins, coupling agents and additional anti-degradants. Antioxidants include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and those listed in WO2012 / 037244.

[0141] As an option, rubber chemicals may be combined with the composite in a mechanical mixer. Specifically, additives such as a filler (which may be the same as or different from the filler used in the mixer; examples of fillers include silica, carbon black, and / or zinc oxide), other elastomers, other or additional masterbatches, antidegradants (e.g., antioxidants), coupling agents, plasticizers, processing aids (e.g., 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, may be added to a mechanical mixer.

[0142] The antidegrading agent (example of a degradation inhibitor) may be an amine-type antidegrading agent, a phenol-type antidegrading agent, an imidazole-type antidegrading agent, a carbamate metal salt, para-phenylenediamine(s) and / or dihydrotrimethylquinoline(s), a polymerized quinine antidegrading agent, and / or a wax and / or other antidegrading agents used in elastomeric 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 l,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 antidegradants may be, for example, diphenyl-p-phenylenediamine and others such as, for example, those described in The Vanderbilt Rubber Handbook (1978), pages 344-346. .

[0143] As an option, when the filler comprises carbon black, an agent may be charged into the mixer (as a filler separate from the filler, with the filler, as a co-pellet, etc.). Without wishing to be bound by any theory, the agent may enhance the dispersion of the filler. The agent may be selected from one or more compounds as described in the provisional applications entitled "METHODS OF PREPARING A COMPOSITE HAVING AN ELASTOMER AND FILLER" and ... CHARGE)” filed on December 9, 2020, (file number 2020914P), and “METHODS OF PREPARING A COMPOSITE HAVING ELASTOMER, FILLER, AND LINKING AGENTS” filed on December 9, 2020, (file number 2020917P).

[0144] Particular types of internal mixers are a Banbury® mixer or a Brabender® mixer, either of which may be used for the composite forming processes described herein. The internal mixer may be a tangential internal mixer. The internal mixer may be a nested internal mixer. Other mixers include a kneading type internal mixer. Internal mixers commercially available from Farrel-Pomini, Harburg Freudenberger Maschinenbau GmbH (HF), Kobelco or Pelmar Eng'r Ltd may be used. In addition to the possibility of using internal steam or water or other fluid circuits in the rotors, in addition or alternatively, the internal mixer may have cooling or heating jackets in one or more regions or portions of the mixing chamber to control the temperature of the components mixed therein.This may create one or more heating / cooling zones in a wall or part of a wall of a mixer. The mixer may be a single-stage mixer or a multi-stage mixer (e.g., two or more stages). Examples of mixers and designs that may be used are described in European Patent No. 2,423,253B1 and US Patent No. 7,556,419.

[0145] As another option, the mixer may be a continuous mixer. For example, the wet natural rubber and filler may be mechanically worked using one or more of a continuous internal mixer, a twin-screw extruder, a single-screw extruder, or a roller mill, such as those described in U.S. Patent 9,855,686 B2. Other suitable masticating and kneading devices are well known and commercially available, including, for example, a continuous mixer and a Unimix® MVX (Mixing, Ventilating, Extrusion) machine from Farrel Pomini Corporation of Ansonia, CT, USA, a continuous mixer, a continuous long mixer from Pomini, Inc., a continuous mixer from Pomini, twin-rotor co-rotating nested extruders, twin-rotor counter-rotating non-nested extruders, continuous compounding extruders, the biaxial grinding extruder produced by Kobe Steel, Ltd., and a Kobe continuous mixer.Another chewing apparatus suitable for use with one or more embodiments described herein will be familiar to those skilled in the art.

[0146] The mixing may be carried out with one or more mixers having at least one rotor and the mixer may be one or more of the following: a kneader, a roller mill, screw extruder, twin-screw extruder, multi-screw extruder, continuous compounding device and / or twin-screw extruder.

[0147] Mixing may be performed with one or more mixers having at least one rotor and the mixer may have two-wing rotors, four-wing rotors, six-wing rotors, eight-wing rotors and / or one or more screw rotors.

[0148] The composite being discharged may be subjected to one or more post-processing steps. Post-processing may be performed after any mixing step. For multi-stage mixing, post-processing may be performed after the first stage and / or after the second stage, and so on. The composite may be post-processed to provide a composite that is dried, homogenized, extruded, calendered, ground, etc. One or more post-processing steps may shape or form or may provide improved handling, but preferably do not substantially disperse the filler. For example, the one or more post-processing steps may impart at most small amounts of energy, e.g., less than 300 kJ / kg of composite, less than 200 kJ / kg of composite, less than 100 kJ / kg of composite, or less than 50 kJ / kg of composite.For example, the one or more post-processing steps do not result in a significant temperature rise of the composite (due to the low energy input).

[0149] As an option, the water content of the evacuated composite may be less than or equal to 5% by weight when evacuated and this water content may be further reduced by one or more additional water or liquid removal steps (if a wet filler is used), such as the use of one or more additional mixing steps, one or more compounding steps, a dryer, or the application of heat, or other means to remove water and optionally other liquids from a mixture, so as to achieve the desired water content of the composite. In general, the post-processing steps may remove from 1% to about 90%, for example from 1% to about 50%, of any remaining liquid phase.

[0150] In any method of producing a composite described herein, the method may further comprise one or more of the following steps, after forming the composite:

[0151] one or more holding steps;

[0152] one or more drying steps may be used to further dry the composite in order to obtain a dried composite;

[0153] one or more extrusion steps;

[0154] one or more calendering steps;

[0155] one or more grinding steps to obtain a ground composite;

[0156] one or more granulation steps;

[0157] one or more cutting steps;

[0158] one or more pressing steps to obtain a pressed product or mixture;

[0159] the mixture or pressed product may be broken to form a granulated mixture; and / or

[0160] one or more mixing or composition steps; and / or

[0161] one or more rolling steps.

[0162] The one or more processing steps may be performed with one or more of an internal mixer, a kneader, a roller mill, a screw extruder, a twin-screw extruder, a multi-screw extruder, a continuous compounding device, and / or a twin-screw extruder equipped with a roller die (e.g., twin-screw mill) or equipped with fixed knives.

[0163] As a further example, the following sequence of steps may occur and each step may be repeated an unlimited number of times (with the same or different settings), after the composite is formed:

[0164] one or more holding steps to develop additional elasticity;

[0165] one or more cooling steps;

[0166] further drying the composite to obtain a more dried composite;

[0167] mixing or compounding the composite to obtain a compound mixture;

[0168] grinding the compound mixture to obtain a ground mixture (e.g., roller grinding);

[0169] granulate the ground mixture;

[0170] optionally press mixture after granulation to obtain a pressed mixture;

[0171] optionally separate the mixture into balls and mix.

[0172] As an option, the composite may be further processed on an open mill. The composite may be discharged from a continuous compounding device or extruder as a length of extrudate and may be cut into smaller lengths before entering the open mill. The composite may optionally be fed to the open mill via a conveyor. The conveyor may be a conveyor belt, conduit, pipe, or other means suitable for transporting the composite from a continuous device to an open mill. The open mill may include a pair of rolls that may optionally be heated or cooled to provide improved operation of the open mill. Other operating parameters of the open mill may include the gap distance between the rolls, the bed height, i.e., the reservoir of material in the gap between and above the rolls, and the speed of each roll.The speed of each cylinder and the temperature of the fluid used to cool each cylinder can be controlled independently for each cylinder. The gap distance can be from about 3 mm to about 10 mm or from about 6 mm to about 8 mm. The cylinder speed can be from about 15 rpm to about 70 rpm, and the cylinders can roll towards each other. relative to the inlet side of the grinder. The friction ratio, the ratio of the speed of the collection cylinder, e.g., the cylinder on which the masticated product accumulates, to that of the rear cylinder, may be from about 0.9 to about 1.1. The fluid used to cool the cylinders may be from about 35°C to about 90°C, e.g., from about 45°C to about 60°C, from about 55°C to about 75°C, or from about 70°C to about 80°C. In addition to controlling the operation of the open grinder to provide a desired level of mastication and drying to the masticated product, it is also desirable that the output of the open grinder be collected on the collection cylinder as a smooth sheet.The residence time of the composite in the mill can be determined in part by the roll speed, gap distance and the amount of mastication and drying desired and can be from about 10 minutes to about 20 minutes for material that has already been masticated, for example, in a twin-rotor continuous mixer.

[0173] Those skilled in the art will recognize that different combinations of devices may be used. Depending on the devices that are used, it may be desirable to operate them under different conditions than those described above to impart varying amounts of work and / or additional drying to the material. In addition, it may be desirable to use more than one particular type of device, e.g., an open mill or an internal mixer, in succession, or to pass the masticated product through a given device more than once. For example, the composite may be passed through an open mill two or three or more times, or passed through two or three or more open mills in succession.In the latter case, it may be desirable to operate each open mill under different operating conditions, e.g., speed, temperature, different (e.g., higher) energy input, etc. The composite may be passed through one, two or three open mills after being mixed in an internal mixer.

[0174] Additionally, or alternatively, the composite may be compounded with one or more antidegradants, rubber chemicals, and / or curing agents, and vulcanized to form a vulcanizate. Such vulcanized compounds may have one or more improved properties, such as one or more improved rubber properties, such as, but not limited to, improved hysteresis, wear resistance, and / or rolling resistance, for example, in tires, or improved mechanical and / or tensile strength, or improved tan delta and / or improved tensile stress ratio, and the like.

[0175] For example, in a compounding step (which may also be the initial mixing step), the ingredients of the curing condition, except for sulfur or any other crosslinking agent and accelerator, are combined with the pure composite in a mixing apparatus (non-curing agents, e.g., rubber chemicals and / or antidegradants, are often pre-mixed and collectively referred to as "smalls"). The most common mixing apparatus is the internal mixer, e.g., the Banbury mixer, but other mixers, such as continuous mixers (e.g., extruders), may also be used. Then, in a second or final compounding stage, the crosslinking agent, e.g., sulfur, and accelerator (if required) (collectively referred to as curing agents) are added. The compounding stage is frequently carried out in the same type of apparatus as the mixing stage but may be carried out on a different type of mixer or extruder or on a roller mill.Those skilled in the art will recognize that once the curing agents have been added, vulcanization will begin once the appropriate activation conditions for the crosslinking agent are reached. Thus, when sulfur is used, the temperature during mixing is preferably kept substantially below the curing temperature.

[0176] Also described herein are methods of making a vulcanizate. The method may include the steps of at least curing a composite in the presence of at least one curing agent. The curing may be accomplished by applying heat, pressure, or both, as is known in the art.

[0177] As an option, vulcanizates prepared from the present composites (e.g., those made by any of the processes of the invention between a filler and uncured natural rubber) may exhibit improved properties. For example, vulcanizates prepared from the present composites may have improved properties compared to a vulcanizate prepared from a composite made by blending a solid elastomer and a filler ("dry blend composite"), particularly dry blend composites having the same composition ("dry blend equivalent"). Thus, the comparison is made between the dry blends and the present blending processes between comparable fillers, elastomers, filler loading level (e.g., ±5 wt. %, ±2 wt. %), and compound formulation, and optionally curing additives.Under these conditions, the vulcanizate has a tan δ value that is less than a tan δ value of a vulcanizate prepared from the dry mix composite having the same composition. Additionally or alternatively, the vulcanizate has a tensile stress ratio, M300 / M100, that is greater than a tensile stress ratio of a vulcanizate prepared from a dry mix composite having the same composition, wherein M100 and M300 refer to the tensile stress at 100% and 300% elongation, respectively.

[0178] Also described herein are articles made from or containing the composite or vulcanizates described herein.

[0179] The composite may be used to produce a product containing an elastomer or rubber. As an option, the elastomeric composite may be used or produced for use, for example, to form a vulcanizate for incorporation into various parts of a tire, for example, tire treads (such as on-road or off-road tire treads), including a cap and base, an undertread, inner gums, tire sidewalls, tire casings, tire sidewall inserts, a tire cord skin, and a contact gum for retreaded tires, in pneumatic tires as well as non-pneumatic or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, caulks, wiper blades, automotive components, liners, pads, housings, pad and wheel members,tire sidewall inserts, tire cord skins, cushion rubber for retreaded tires, in pneumatic tires as well as non-pneumatic tires or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, seals, wiper blades, automotive components, liners, pads, housings, pad and wheel elements, tire sidewall inserts, tire cord skins, cushion rubber for retreaded tires, in pneumatic tires as well as non-pneumatic tires or solid tires. Alternatively or additionally, an elastomeric composite (and subsequently a vulcanizate) may be used for hoses, seals, gaskets, anti-vibration articles, tracks, track pads for tracked vehicle equipment,engine mounts, seismic stabilizers, mining equipment such as screens, mining equipment packings, conveyor belts, chute liners, slurry pump liners, slurry pump components such as impellers, valve seats, valve bodies, piston hubs, piston rods, plungers, impellers for various applications such as mixing slurries and slurry pump impellers, mill liners, cyclones and hydrocyclones, expansion joints, marine equipment such as packings 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, petroleum, aerospace and other applications, propeller shafts, pipeline packings for conveying, e.g.,oil sands and / or tar sands, and, other applications where improved abrasion resistance and / or dynamic properties are desired. In addition, the elastomeric composite, via the vulcanized elastomeric composite, can be used in cylinders, cams, shafts, hoses, vehicle bearings, or in other applications where improved abrasion resistance and / or dynamic properties are desired.

[0180] Accordingly, the articles include vehicle tire treads, including the cap and base, sidewalls, undertreads, inner liners, cord skin components, tire casings, engine mounts, bushings, conveyor belt, anti-vibration devices, seals, wiper blades, automotive components, seals, gaskets, hoses, liners, bushings, housings, and wheel or track members. For example, the article may be a multi-component tread, as described in U.S. Patents 9,713,541, 9,713,542, 9,718,313, and 10,308,073.

[0181] Optionally, the present methods may incorporate suitable fillers, elastomers, mixing and compounding processes, composites, vulcanizates, additives, blenders and other disclosures described in PCT Publication No. WO 2020 / 247663. EXAMPLES

[0182] The examples describe the preparation of a composite of elastomer and corresponding vulcanizates from never-dried natural rubber with several particulate fillers as well as comparative composites prepared in a similar manner but from dried natural rubber.

[0183] All mixing and compounding processes were performed with a BR-1600 Banbury® mixer (“BR1600”; Manufacturer: Farrell). The BR1600 mixer operated using two 2-wing (2WL) tangential rotors, providing a capacity of 1.6L.

[0184] A water content in the evacuated composite was measured using a moisture analyzer (Model: HE53, Manufacturer: Mettler Toledo NA, Ohio). The composite was cut into small pieces (size: length, width, height <5 mm) and 2 to 2.5 g of material was placed on a disposable aluminum disc / plate which was placed inside the moisture analyzer. The weight loss was recorded for 30 minutes at 125°C. After 30 minutes, the moisture content of the composite was recorded as follows:

[0185] moisture\ content\ of\ composite=\left(\frac{initial\ weight-final\ weight} {initial\ weight}\right)\astlOO.

[0186] The carbon black loading in the composite was determined by thermo- gravimetric (model Q500 unit, manufacturer: TA Instruments, DE). Approximately 15 to 20 mg of rubber samples were used. The samples were first heated under a nitrogen atmosphere at room temperature to 125°C at 30°C / min and isothermal for 30 min to remove moisture, then heated to 550°C at 30°C / min and isothermal for 5 min to determine the organic matter content, which is mainly the rubber content. After the atmosphere was switched to air, samples were then heated to 800°C at 30°C / min and isothermalized for 15 min to determine the carbon black (CB) content. CB loadings were then calculated as the carbon black content divided by the organic content.

[0187] The following tests were used to measure the rubber properties on each of the vulcanizates:

[0188] Tensile stress at 100% elongation (Ml00) and tensile stress at 300% elongation (M300) were evaluated by ASTM D412 (Test Method A, Matrix C) at 23°C, 50% relative humidity and a crosshead speed of 500 mm / min. Extensometers were used to measure the tensile stress. The ratio M300 / M100 is called the tensile stress ratio (or modulus ratio).

[0189] Max tan ô was measured with an ARES-G2 rheometer (Manufacturer: TA Instruments) using an 8 mm diameter parallel plate geometry in torsional mode. The vulcanizate specimen diameter was 8 mm in diameter and approximately 2 mm thick. The rheometer was operated at a constant temperature of 60°C and a constant frequency of 10 Hz. Strain sweeps were performed from a strain amplitude of 0.1 to 68%. Measurements were taken at ten points per decade and the maximum measured tan ô (“max tan ô”) was recorded, also referred to as “tan ô” unless otherwise stated.

[0190] Composition procedures

[0191] To convert composites into vulcanizable products, one or two additional mixing steps were performed. These procedures were the same for all inventive and comparative examples. If two mixing steps were applied, a first mixing method is described in Table 1:

[0192] [Tables 1] Filling rate 68%; TCU = 50°C; 80 rpm; plunger pressure = 2.8 bar Time (s) Description 0 Add composite 180 Pour

[0193] The final stage mixing process for all compounds is described in Table 2:

[0194] [Tables2] Filling rate 65%; TCU = 50°C; 60 rpm; plunger pressure = 2.8 bar Time (s) Description 0 Add composite and curing agents 30 Sweep 60 Pour

[0195] After each mixing stage, the composites were sheeted on a 2-roll mill operated at 50°C and about 37 rpm, followed by four passes with a nip of about 5 mm, with a rest time of at least 3 hours before the next mixing stage.

[0196] The final compounds were cured in a press heated to 150°C for a certain time, T90+ 10% of T90, where T90 is the time to reach 90% vulcanization, determined by a usual rubber rheometer.

[0197] Examples 1 and 2: Natural rubber / carbon black N234

[0198] These examples describe the preparation of composites and corresponding vulcanizates from never-dried natural rubber via a batch mixing process, as compared to composites and vulcanizates prepared from solid natural rubber.

[0199] The never-dried natural rubber used in Examples 1 and 2 was obtained from Hokson Rubber, Malaysia. The never-dried natural rubber was a natural latex that was naturally coagulated in air and harvested directly from the tree to obtain a natural rubber coagulum in the form of lumps (golet lumps). This coagulum was washed with water to remove some of the impurities present, resulting in a coagulum containing 27% by weight of water based on the weight of the coagulum.

[0200] The filler used for Examples 1 and 2 and the comparative examples was Vulcan® 7H carbon black (N234) from Cabot Corporation.

[0201] Examples 1 and 2 were mixed according to the procedure described in Table 3, in which the time intervals indicated refer to the time period from the start of mixing, defined as "0 s".

[0202] [Tables3] Filling rate 70%; TCU = 100°C; 80 rpm; plunger pressure = 2.8 bar Time (s) Description 0 Add 2 / 3 polymer and 2 / 3 filler 180 Add 1 / 3 polymer and 1 / 3 filler 210 Sweep / scrape 375 Add 6PPD, ZnO and stearic acid Scrape / sweep at 140°C Dump at 150°C

[0203] For the comparative examples, the solid dry natural rubber was SMR 20 with a moisture content < 1% by weight (Hokson Rubber, Malaysia). (Note that if the starting coagulum of Examples 1 and 2 had been completely dried and baled, it would be considered an SMR 20 natural rubber grade.) Technical descriptions of this natural rubber are widely available, such as in the Blue Book of Rubber World Magazine published by Lippincott and Peto, Inc. (Akron, Ohio, USA).

[0204] Comparative Examples C1 and C2 were mixed according to the procedure described in Table 4.

[0205] [Tables4] Filling rate 70%; TCU = 50°C; 80 rpm; plunger pressure = 2.8 bar Time (s) Description 0 Add polymer 30 Add 3 / 4 charge 60 Add 1 / 4 charge 180 Add 6PPD, ZnO and stearic acid 240 Scrape / sweep 300 Pour out

[0206] The formulation used in Examples 1 and 2 and Comparative Examples C1 and C2 is Formulation 1 given in Table 5. The 6PPD was N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, the zinc oxide, stearic acid and sulfur were standard rubber grades, and CBS (N-cyclohexyl-2-benzothiazole sulfenamide) was Accelerator CBTS, all available from Akrochem, Akron, Ohio.

[0207] [Tables5] Formulation 1 (phr) Formulation 2 (phr) NR 100 NR 100 CB var CB var “smalls” 6PPD 2 6PPD 1.5 Zinc Oxide 3 Zinc Oxide 5.0 Stearic Acid 2.5 Stearic Acid 3.0 Wax Beads 1.5 Processing Oil 2.5 Hardeners CBS 1.2 TBBS 1.4 Sulfur 1.2 Sulfur 1.2

[0208] Table 6 provides the additional properties of the composite before compounding as well as the rubber properties of the corresponding vulcanizates. "Water in starting rubber" refers to the amount of water in the coagulum, for Examples 1 and 2, or the solid natural rubber of Comparative Examples C1 and C2.

[0209] [Tableauxô] Example 1 Example 2 Comparative Cl Comparative C2 Water in starting rubber (%) 27 27 <1 <1 Stage 1 mixing time (s) 486 445 300 300 Water content of composite after stage 1 (%) 1.4 1.0 0.4 0.8 Total number of mixing stages 2 3 2 3 Final CB content (phr) 45 46 47 48 M100 (MPa) 2.22 2.18 2.66 2.60 M300 (MPa) 13.5 13.6 14.0 14.3 M300 / M100 6.09 6.23 5.26 5.48 Tan ô (max) 0.165 0.176 0.192 0.199

[0210] From the data in Table 6, it can be observed that vulcanizates prepared from the composites prepared by the claimed processes show: (a) a higher tensile stress ratio (M300 / M100), and (b) a lower tan δ compared to the dry mix comparative examples C1 and C2.

[0211] Examples 3 and 4: Natural rubber / carbon black N134

[0212] These examples describe the preparation of composites and corresponding vulcanizates from never-dried natural rubber via a batch mixing process, as compared to composites and vulcanizates prepared from solid natural rubber.

[0213] The never-dried natural rubber used in these examples and the dry natural rubber used for the comparative example (comparative example C3) were the same as those used in examples 1 and 2, and comparative examples C1 and C2, respectively.

[0214] The filler used in these examples was dried pellets of VULCAN® 10H (N134) carbon black from Cabot Corporation. For Example 4, the carbon black was wetted with water. To produce wet carbon black, approximately 1 kg of carbon black was immersed in excess water, and reduced pressure (vacuum) was applied to the headspace above the water-carbon black mixture to remove entrapped air. After all the air was removed, the excess water was drained using a coarse filter, and the residual wet pellets were surface dried in an oven set at 105°C until the moisture content of the wet pellets reached approximately 50% by weight. The wet pellets were then removed from the oven and cooled.

[0215] In Examples 3 and 4, a 3-stage mixing process as described in Tables 1, 3, and 4 was used, and Formulation 2 of Table 5 was applied. The wax was Sunproof™ Improved Wax, the oil was Calight RPO® Oil, and the TBBS (N-tert-butyl-2 benzothiazole sulfenamide) was Accelerator BBTS, all available from Akrochem, Akron, Ohio. In Comparative Example C3, mixing procedures described in Tables 2, 3, and 4 were used, and Formulation 2 of Table 5 was applied.

[0216] Table 7 provides additional properties of the composite before compounding as well as the rubber properties of the corresponding vulcanizates. "Water in starting rubber" refers to the amount of water in the coagulum, for Examples 3 and 4, or the solid natural rubber of Comparative Example C3.

[0217] [Tables7] Example 3 Example 4 Comparative C3 Water in rubber (%) 27 27 <1 Water content of carbon black (%) <1 52 <1 Stage 1 mixing time (s) 445 910 300 Final CB content (phr) 48 50 49 M100 (MPa) 2.03 2.74 2.23 M300 (MPa) 11.75 16.37 12.92 M300 / M100 5.79 5.97 5.79 Tan ô (max) 0.161 0.169 0.196

[0218] From the data in Table 7, it can be observed that vulcanizates prepared at from the composites prepared by the claimed processes show: (a) an equal or higher tensile stress ratio (M300 / M100), and (b) a lower tan δ compared to the dry mix of Comparative Example C3.

[0219] Examples 5 and 6: Natural rubber / carbon black N134

[0220] These examples describe the preparation of composites and corresponding vulcanizates from undried natural rubber and wet carbon black pellets via a continuous mixing process, as compared to composites and vulcanizates prepared from dry carbon black and solid natural rubber.

[0221] The never-dried rubber used in Examples 5 and 6 was obtained from Hokson Rubber, Malaysia. The never-dried natural rubber was a natural latex that was naturally coagulated in the air and harvested directly from the tree to obtain a natural rubber coagulum in the form of lumps (golet lumps). This coagulum was washed with water and granulated, resulting in a never-dried rubber containing 25% by weight of water based on the weight of the coagulum.

[0222] The carbon black used in Examples 5 and 6 is Vulcan® 10H (N134) carbon black from Cabot Corporation which was obtained after the pelletizing step in the normal carbon black manufacturing process, but before the drying step. Some reduction in the water content of these pellets occurred during handling, packaging and transportation. The final water content of the wet pellets used in Examples 5 and 6 was 42% by weight.

[0223] For Examples 5 and 6, the never-dried natural rubber was fed into the feed hopper of a screw dewatering press (French Oil Mill Machinery Company, Piqua, OH) at a rate of 300 kg / h. The wet carbon black pellets were continuously fed to the same feed hopper using a screw feeder. After exiting the mill, the rubber-carbon black mixture still contained > 10% water at that time. This mixture was conveyed to the feed hopper of an FCM™ mixer (Farrel Pomini's Farrel Continuous Mixer equipped with #7 and #15 rotors) and subjected to intensive mixing at 300 rpm, resulting in a rapid temperature rise to approximately 140°C. After exiting the continuous mixer, the composite was conveyed to a 2-roll mill which homogenized, cooled, and sheeted the material. The composite was removed from the roller mill in the form of ribbons.

[0224] For Comparative Examples C4 and C5, the dry rubber used was SMR 5 natural rubber. (Note that if the starting coagulum of Examples 5 and 6 had been completely dried and baled, it would be considered an SMR 5 natural rubber grade.) Technical descriptions of this natural rubber are widely available, such as in the Blue Book of Rubber World Magazine published by Lippincott and Peto, Inc. (Akron, Ohio, USA). The carbon black used was Vulcan® 10H carbon black. Blending was carried out as a batch process using the procedure described in Table 4.

[0225] To produce vulcanized compounds from the composites produced in Examples 5 and 6 and Comparative Examples C4 and C5, the composites were mixed in a single step using the procedure given in Table 8 and Formulation 1 in Table 5. Table 9 provides additional properties of the composite before compounding and the rubber properties of the corresponding vulcanizates. “Water in starting rubber” refers to the amount of water in the coagulum, for Examples 5 and 6, or the solid natural rubber of Comparative Examples C4 and C5.

[0226] [Tables8] Filling rate 70%; TCU = 50°C; 60 rpm; plunger pressure = 2.8 bar Time (s) Description 0 Add composite 15 Add 6PPD, ZnO and stearic acid 90 Add curing agents 120 Scrape / sweep 150 Pour out

[0227] [Tables9] Example 5 Example 6 Comparison C4 Comparison C5 Water in starting rubber (%) 25 25 <1 <1 Water content of carbon black (%) 42 42 <1 <1 Water content of composite after stage 1 (%) 2.4 2.7 0.5 0.5 Total number of mixing stages 2 2 2 2 Final CB content (phr) 32 38 32 38 M100 (MPa) 1.8 2.1 1.5 1.8 M300 (MPa) 10.6 12.5 8.6 10.3 M300 / M100 6.06 5.96 5.73 5.74 Tan ô (max) 0.091 0.125 0.124 0.138

[0228] From the data in Table 9, it can be observed that vulcanizates prepared from the composites prepared by the claimed processes show: (a) an equal or higher tensile stress ratio (M300 / M100), and (b) a lower tan δ compared to the comparative dry mix examples C4 and C5.

[0229] The terms "comprising," "having," "including," and "containing" are to be considered open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise indicated. The value range statements herein are intended merely as a shorthand method for individually indicating each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the description as if individually indicated herein. All methods described herein may be performed in any suitable order unless otherwise indicated herein or clearly contradicted by the context.The use of any and all examples, or exemplary language (e.g., such as "such as") provided herein, is intended merely to better illustrate the invention and is not intended to limit the scope of the present invention unless clearly claimed. No language in the description should be construed as indicating any unclaimed element essential to the practice of the present invention.

Claims

Claims

1. A method of preparing a composite, comprising the steps of: a. charging a mixer separately with at least one never-dried natural rubber and a filler, wherein the never-dried natural rubber has water present in an amount in the range of 5% to 55% by weight of the never-dried natural rubber; b. in one or more mixing steps, mixing the at least one never-dried natural rubber and the filler to form a mixture, and in at least one of said mixing steps, carrying out said mixing at mixer temperatures controlled by at least one temperature control means, and removing at least some of the water from the mixture by evaporation; and c.discharging, from the mixer, the composite comprising the filler dispersed in the natural rubber at a filler level of at least 20 phr, wherein the composite has a water content of not more than 5% by weight based on the total weight of said composite.

2. The method of claim 1, wherein the never-dried natural rubber is a coagulum.

3. The method of claim 1, wherein the never-dried natural rubber is a coagulum formed by exposing natural rubber latex to air under ambient conditions.

4. The method of claim 1, wherein the never-dried natural rubber is a coagulum formed by exposing a natural rubber latex to a salt or an acid or both.

5. A method according to any one of claims 1 to 4, wherein before loading in step (a), the never-dried natural rubber is washed with water to reduce impurities.

6. A method according to any one of claims 1 to 5, wherein prior to loading in step (a), the never-dried natural rubber is subjected to expression, compaction, dewatering or combinations thereof.

7. A method according to any one of claims 1 to 6, wherein the never-dried natural rubber has said water present in an amount in the range of 10 wt% to 40 wt%.

8. A method according to any one of claims 1 to 7, wherein the filler is dispersed in the natural rubber at a loading in the range of 20 to 100 phr.

9. A method according to any one of claims 1 to 8, wherein the filler has a liquid content of less than 10% by weight, based on the weight of the filler, and is in the form of a powder or pellet.

10. A method according to any one of claims 1 to 9, wherein the filler is a wet filler comprising a filler moistened with a liquid, the wet filler having a liquid content of at least 10% by weight, based on the weight of the wet filler, and is in the form of a powder, paste, pellet or cake.

11. A method according to any one of claims 1 to 10, wherein the charging step (a) and the one or more mixing steps (b) may be carried out in the presence of one or more rubber chemicals in an amount of less than 5%, or less than 1%, by weight of the total amount of rubber chemicals ultimately in the composite discharged in step (c).

12. A method according to any one of claims 1 to 11, wherein the evacuated composite has a water content of not more than 2% by weight.

13. A method according to any one of claims 1 to 12, wherein a time period between the start of mixing and discharge is in the range of 5 min to 30 min.

14. A method according to any one of claims 1 to 13, wherein during said mixing, the mixer has one or more rotors operating at a tip speed of at least 0.5 m / s for at least 50% of the mixing time.

15. The method of any one of claims 1 to 14, wherein the filler comprises at least one material selected from carbonaceous materials, carbon black, silica, nanocellulose, lignin, clays, nanoclays, metal oxides, metal carbonates, pyrolysis carbon, graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-walled carbon nanotubes, multi-walled carbon nanotubes, a filler coated and treated with these, and combinations thereof.

16. A method according to any one of claims 1 to 15, wherein when charging the mixer with at least a portion of the never-dried natural rubber, the never-dried natural rubber is heated to a temperature of 90°C or higher before charging the mixer with at least a portion of the feedstock.

17. A method according to any one of claims 1 to 16, wherein, during loading or mixing, the method further comprises adding at least one antidegradant.

18. A method according to any one of claims 1 to 17, wherein said mixing is carried out in one mixing step.

19. A method according to any one of claims 1 to 17, wherein said mixing is carried out in two mixing stages.

20. A method according to any one of claims 1 to 19, wherein after said discharging, said method further comprises at least one additional processing step selected from extrusion, calendering, grinding, granulating, baling, compounding and sheeting.

21. A method of preparing a composite in an integrated manufacturing operation, comprising the steps of: a. producing a never-dried natural rubber from latex recovered from natural latex sources in a latex or rubber manufacturing facility; b. conveying said never-dried natural rubber to at least one mixer; c. charging said at least one mixer with at least one never-dried natural rubber and at least one filler; wherein the never-dried natural rubber has water present in an amount in the range of 5% to 55% by weight of the never-dried natural rubber; d.in one or more mixing steps, mixing the at least one never-dried natural rubber and the filler to form a mixture, and in at least one of said mixing steps, carrying out said mixing at mixer temperatures controlled by at least one temperature control means, and removing at least some of the water from the mixture by evaporation; and e. discharging, from the at least one mixer, the composite. comprising the filler dispersed in the never-dried natural rubber at a filler level in the range of 20 to 100 phr, wherein the composite has a water content of not more than 5% by weight based on the total weight of said composite.