Syndiotactic polybutadiene dispersion and method for preparing same

Abstract

A room-temperature flowable dispersion of syndiotactic polybutadiene particles in an aqueous mixture containing at least one emulsifier. The dispersion reduces the need for temperature control equipment for storing or transporting the dispersion during processing. The syndiotactic polybutadiene particles in the dispersion are formed from a syndiotactic polybutadiene cement containing a hydrocarbon solvent obtained from a polymerization process, and the hydrocarbon solvent is subsequently removed from the dispersion by evaporation.

Description

[Technical Field]

[0001] The present disclosure relates to dispersions of syndiotactic polybutadiene, particularly aqueous dispersions of solidified syndiotactic polybutadiene particles containing an emulsifier, which are flowable at room temperature. The present disclosure also relates to a method for preparing an aqueous dispersion of syndiotactic polybutadiene from a syndiotactic polybutadiene-containing cement after polymerization. [Background technology]

[0002] Polymerization of syndiotactic polybutadiene in hydrocarbon solvents produces a polymer cement that is transported for storage or further used in downstream processes. The production of syndiotactic polybutadiene can present difficulties because the polymer is often poorly soluble in the polymerization solvent and can solidify and agglomerate into clumps below its higher melting point, thereby reducing the flowability of the cement and making it difficult to transport.

[0003] To prevent solidification of the syndiotactic polybutadiene, the cement or its post-polymerization contents must be maintained above the melting temperature of the polymer, for example, to facilitate transport or storage to a solvent removal process for preparing the polymer product. If solidification of the polymer in the cement progresses, the cement must be reheated to form a flowable liquid for processing. The temperature control required to process syndiotactic polybutadiene can make polymerization production and downstream processes difficult, requiring precise timing, sophisticated equipment setup, monitoring, and control. Even short-term storage of syndiotactic polybutadiene-containing cement in standard containers requires heating means to maintain a flowable cement. The additional risk of fouling of unheated or temporarily heat-deprived components is an undesirable factor when processing syndiotactic polybutadiene-containing cement at lower temperatures.

[0004] There is a need to improve the flow properties and hardening problems of syndiotactic polybutadiene-containing cements after polymerization. The present disclosure relates to methods for improving the flow properties of syndiotactic polybutadiene cements after polymerization, which in turn improves the storability of the cement and reduces the risk of hardening and equipment fouling. Summary of the Invention

[0005] In a first aspect, a syndiotactic polybutadiene dispersion is disclosed, the syndiotactic polybutadiene dispersion comprising solidified syndiotactic polybutadiene particles in an aqueous mixture with an emulsifier.

[0006] In one embodiment of Aspect 1, the dispersion comprises one or more hydrocarbon polymerization solvents, such as hexane or butene.

[0007] In another embodiment of Aspect 1, the dispersion is substantially free of hydrocarbon solvents, such as residual solvents remaining from the polymerization or residual solvents remaining from the syndiotactic polybutadiene cement used to form the dispersion, e.g., less than 0.05 weight percent based on the total weight of the dispersion.

[0008] In another embodiment of Aspect 1, the emulsifier is a sulfonate or sulfate compound. The sulfate compound may be sodium lauryl sulfate, sodium tetradecyl sulfate, sodium dodecyl sulfate, and combinations thereof.

[0009] In another embodiment of Aspect 1, the weight ratio of emulsifier to syndiotactic polybutadiene particles in the dispersion ranges from 2-20.

[0010] In another embodiment of Aspect 1, the total amount of emulsifier present in the dispersion ranges from 0.05 to 3 weight percent, based on the total weight of the dispersion. In one embodiment, the dispersion contains only one emulsifier, which can be a sulfate compound.

[0011] In another embodiment of Aspect 1, the syndiotactic polybutadiene particles present in the dispersion range from 2 to 20 weight percent based on the total weight of the dispersion.

[0012] In another embodiment of Aspect 1, the water present in the dispersion ranges from 35 to 65 weight percent based on the total weight of the dispersion.

[0013] In another embodiment of Aspect 1, the syndiotactic polybutadiene particles of the dispersion are uniformly distributed solid particles, and the dispersion is fluid at room temperature or in the range of 20°C to 30°C.

[0014] In a second aspect, there is disclosed a rubber composition comprising the syndiotactic polybutadiene particles of the syndiotactic polybutadiene dispersion of aspect 1 and an emulsifier, wherein the rubber composition is substantially free of water and solvents that were present in the dispersion.

[0015] In one embodiment of Aspect 2, the rubber composition is substantially free of any polymerization solvent present in the syndiotactic polybutadiene dispersion of Aspect 1.

[0016] In another embodiment of Aspect 2, the rubber composition includes 0.1 to 3 parts by weight of a dispersion-derived emulsifier based on 100 parts of the rubber component of the rubber composition.

[0017] In another embodiment of Aspect 2, the rubber composition comprises 1 to 30 parts by weight of dispersion-derived syndiotactic polybutadiene particles, based on 100 parts of the rubber component of the rubber composition.

[0018] In another embodiment of Aspect 2, the rubber composition comprises 10 to 20 phr of dispersion-derived syndiotactic polybutadiene particles.

[0019] In a third aspect, a method for preparing a syndiotactic polybutadiene dispersion is disclosed, the method comprising the steps of combining a syndiotactic polybutadiene polymerization cement with water and an emulsifier to form a premix; subjecting the premix to a mixing step to form a dispersion; and cooling the dispersion to solidify the syndiotactic polybutadiene present in the dispersion, e.g., dissolved in the dispersion, into particles to form a final, fluid dispersion.

[0020] In one embodiment of Aspect 3, the mixing step includes subjecting the premix to shear, for example, high shear.

[0021] In another embodiment of Aspect 3, the pre-mix is ​​at a temperature greater than 60° C. at the start of the mixing step. The pre-mix may be further maintained at a temperature greater than 60° C. during the mixing step before cooling the formed dispersion.

[0022] In another embodiment of Aspect 3, the dispersion can have a weight ratio of emulsifier to syndiotactic polybutadiene in the cement ranging from 2-20.

[0023] In another embodiment of Aspect 3, the premix comprises at least one of the following amounts: the syndiotactic polybutadiene present in the premix is ​​in the range of 2 to 20 weight percent based on the total weight of the premix; the water present in the premix is ​​in the range of 35 to 65 weight percent based on the total weight of the premix; and the total amount of emulsifiers present in the premix is ​​in the range of 0.05 to 3 weight percent based on the total weight of the premix.

[0024] In another embodiment of Aspect 3, the solidified syndiotactic polybutadiene particles of the dispersion are uniformly distributed solid particles, and the dispersion is flowable at room temperature or in the range of 20°C to 30°C.

[0025] In a fourth aspect, a method for preparing a syndiotactic polybutadiene dispersion is disclosed, comprising the steps of combining syndiotactic polybutadiene cement from a reaction vessel with a stream comprising water and an emulsifier to form a premix; feeding the premix to a colloid mill and mixing the premix to form a dispersion; and cooling the dispersion discharged from the colloid mill to solidify the syndiotactic polybutadiene into particles.

[0026] In one embodiment of Aspect 4, the colloid mill applies shear to the premix.

[0027] In another embodiment of Aspect 4, the step of combining the syndiotactic polybutadiene cement from the reaction vessel with the stream of water and emulsifier is an in-line process. One example of an in-line process is to merge a first pipe with a second pipe to form a single feed pipe to the colloid mill. The first pipe contains the stream of syndiotactic polybutadiene cement, and the second pipe contains the stream of water and emulsifier.

[0028] In another embodiment of Aspect 4, the step of combining the syndiotactic polybutadiene cement from the reaction vessel with the stream of water and emulsifier occurs in concentric tubes in fluid communication with the inlet of the colloid mill. The concentric tubes have an inner tube and an outer tube. The inner tube contains one of the syndiotactic polybutadiene cement or the water and the emulsifier, and the outer tube contains one of the syndiotactic polybutadiene cement or the water and the emulsifier, none of which components are present in the inner tube.

[0029] In another embodiment of Aspect 4, the colloid mill has a gap between the outer surface of the rotor and the inner wall surface of the mill casing or the inner wall surface of the stator, through which the premix flows during mixing, the gap being in the range of 0.02 to 2.3 millimeters (mm).

[0030] In another embodiment of Aspect 4, the colloid mill has a rotor and is operated in the range of 700 to 7500 revolutions per minute (rpm), or 2000 to 4500 rpm.

[0031] In another embodiment of Aspect 4, the premix is ​​fed to the colloid mill at a temperature ranging from 70°C to 100°C.

[0032] In another embodiment of Aspect 4, the emulsifier in the premix is ​​present in the range of 2 to 10 parts per 100 parts of syndiotactic polybutadiene.

[0033] In another embodiment of Aspect 4, the stream comprising water and emulsifier is provided from a supply tank holding a preformed slurry comprising water and one or more emulsifiers.

[0034] In another embodiment of Aspect 4, the syndiotactic polybutadiene cement and the stream of water and emulsifier are combined immediately prior to being fed to the colloid mill. For example, the ingredients are combined for less than 1 minute, less than 30 seconds, or less than 15 seconds before being fed to the colloid mill.

[0035] In another embodiment of Aspect 4, the weight ratio of water to diotactic polybutadiene cement ranges from 1:1 to 5:1, or from 1.5:1 to 3:1.

[0036] The above aspects (or examples of these aspects) may be provided alone or in combination with any one or more of the example aspects or example aspects described above. For example, the first aspect may be provided alone or in combination with any one or more of the example aspects of the first, second, third, or other aspects described above.

[0037] Additional features and advantages are set forth in the following Detailed Description, and in part will be readily apparent to those skilled in the art from this description or will be recognized by practicing the embodiments described herein, including the following Detailed Description, Claims, and Accompanying Drawings. [Brief explanation of the drawings]

[0038] These and other features, examples, and advantages of aspects or embodiments of the present disclosure will be better understood by reading the following detailed description in conjunction with the accompanying drawings. [Figure 1] FIG. 1 shows a process schematic for preparing a dispersion of post-polymerization syndiotactic polybutadiene. [Figure 2] FIG. 2 shows a process schematic for preparing a dispersion of post-polymerization syndiotactic polybutadiene. DETAILED DESCRIPTION OF THE INVENTION

[0039] The terminology used herein is for the purpose of describing the embodiments only and should not be construed as limiting the invention as a whole.

[0040] As used herein, when a range is given, such as 5 to 25 (or 5-25), this range preferably means at least 5 or greater than 5, and separately and independently preferably means less than 25 or less than or equal to 25. In some instances, such ranges independently specify 5 or greater, and separately and independently specify 25 or less.

[0041] As used herein, the terms "substantial," "substantially," and variations thereof are intended to refer to a described characteristic being equal to or approximately equal to a value or description. For example, a "substantially planar" surface is intended to mean a surface that is planar or nearly planar. Furthermore, it should be noted that the terms "substantially" and "about" may be utilized herein to express the inherent degree of uncertainty that may result from any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to express the extent to which a quantitative representation may vary from the stated basis without resulting in a change in the basic functionality of the object in question.

[0042] The present disclosure relates to a fluid dispersion of syndiotactic polybutadiene particles in an aqueous mixture containing at least one emulsifier. The dispersion is fluid at lower temperatures (<30°C), including room temperature, beneficially reducing the need for temperature control equipment and monitoring for storing or transporting the dispersion during processing operations. The syndiotactic polybutadiene particles in the dispersion can be formed from a syndiotactic polybutadiene cement, such as a syndiotactic polybutadiene cement obtained from a polymerization process. The syndiotactic polybutadiene cement may contain one or more hydrocarbon solvents utilized as a polymerization solvent, which contain dissolved or aggregated coagulum or clumps of syndiotactic polybutadiene formed.

[0043] Dispersions of syndiotactic polybutadiene are prepared by treating syndiotactic polybutadiene following its polymerization. Syndiotactic polybutadiene cement or reaction product containing one or more hydrocarbon solvents is combined with water and an emulsifier, e.g., a slurry of water and emulsifier, preferably at a temperature at or above the temperature required to solubilize the syndiotactic polybutadiene in the one or more hydrocarbon solvents or to render the cement fluid for mixing purposes. In one embodiment, the syndiotactic polybutadiene cement is at a temperature such that the syndiotactic polybutadiene is completely dissolved in the solvent present in the cement when the water and emulsifier are combined with the cement. The combined syndiotactic polybutadiene cement, water, and emulsifier are mixed to form a dispersion of syndiotactic polybutadiene particles in a mixture of polymerization-derived hydrocarbon solvent, water, and emulsifier. Mixing is preferably performed at the same or similar temperature as that used to combine the water and emulsifier with the syndiotactic polybutadiene cement.

[0044] The mixed dispersion is cooled to solidify the syndiotactic polybutadiene of the mixed dispersion into particles that can substantially retain their morphology resulting from mixing, or from a uniformly dispersed, dissolved form. The solidified syndiotactic polybutadiene particles in the dispersion do not coalesce with each other, and therefore the dispersion remains fluid after the temperature is reduced from the mixing stage. The emulsifier present in the dispersion promotes the solidification of the syndiotactic polybutadiene into discrete particles that do not aggregate with each other. The formed dispersion may be stored or subjected to additional processing steps, such as solvent removal to reduce the presence of any polymerization solvent in the dispersion.

[0045] As described above, syndiotactic polybutadiene dispersions can be formed by methods starting with a syndiotactic polybutadiene-containing cement resulting from a polymerization process. The syndiotactic polybutadiene-containing cement resulting from the polymerization process can be at an elevated temperature, for example, in the range of 60 to 160°C, or 70 to 120°C. The elevated temperature of the syndiotactic polybutadiene-containing cement ensures that the syndiotactic polybutadiene polymer remains dissolved or fluid and flowable in the cement, facilitating transportation and storage of the polymer cement after polymerization. To process the syndiotactic polybutadiene-containing cement to form a syndiotactic polybutadiene dispersion, it is preferred that the cement be at a temperature of at least 60°C, or in the range of 60°C to 100°C, to aid in blending and mixing of the other components of the dispersion, such as emulsifiers.

[0046] Syndiotactic polybutadiene-containing cement may contain syndiotactic polybutadiene, one or more polymerization solvents, and other polymerized or unreacted compounds. In one or more embodiments, the syndiotactic polybutadiene-containing cement contains 2 to 30, 3 to 25, or 4 to 20 weight percent syndiotactic polybutadiene, based on the total weight of the syndiotactic polybutadiene-containing cement. The polymerization solvent substantially constitutes the remainder of the cement. The solvent can be an organic solvent inert to the polymerization reaction, such as a hydrocarbon solvent, including aliphatic, alicyclic, and aromatic hydrocarbon compounds. Hydrocarbon solvents preferably have 3 to 8 carbon atoms, and include, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. These solvent compounds may be used alone or in combination of two or more.

[0047] The syndiotactic polybutadiene-containing cement is first combined with water, one or more emulsifiers, a mixture of both, and other ingredients to form a premix that can be mixed to form a dispersion. The water and emulsifier can be combined with the syndiotactic polybutadiene-containing cement, for example, by adding the components individually or together, or by introducing the cement into the water and / or emulsifier. The water and emulsifier combination may optionally be preheated before adding the cement components. In one example, the water and emulsifier can be preheated in a vessel or desolventizer before adding the syndiotactic polybutadiene-containing cement to the water and emulsifier mixture. Operating the mixing step in the desolventizer advantageously removes the polymerization solvent from the mixture, reducing or eliminating downstream operations for solvent removal of the formed dispersion. The temperature in the desolventizer can be maintained above the boiling point of the polymerization solvent but below the boiling point of the water and emulsifier mixture, for example, in the range of 60°C to 95°C, or 65°C to 80°C. The vessel or desolventizer may be equipped with an agitator or other mixing means to carry out the step of mixing the premix to form the syndiotactic polybutadiene dispersion.

[0048] The components may be combined in a vessel or suitable container such that they can be introduced by conventional means (e.g., a transfer pump). The water and emulsifier, when combined with the polymer cement, may be at any suitable temperature, for example, in the range of 20°C to 60°C, 25°C to 50°C, or 30°C to 40°C. The formed premix should be at a temperature of at least 60°C or in the range of 60°C to 100°C to aid in blending and mixing of the other components of the dispersion.

[0049] In another embodiment, a premix of syndiotactic polybutadiene-containing cement, water, one or more emulsifiers, a mixture of both, and other ingredients can be formed in-line by combining a stream of syndiotactic polybutadiene-containing cement transported from a reactor with a stream containing at least water and one or more emulsifiers. For example, syndiotactic polybutadiene-containing cement from the reactor discharge or outlet pipe can be combined with a stream containing water and one or more emulsifiers. The water and one or more emulsifiers can be preformed before being combined with the reactor discharge; for example, a slurry of water and one or more emulsifiers can be prepared in a vessel, transported, and combined with the syndiotactic polybutadiene-containing cement discharge stream to form a premix. Using existing equipment and piping to process and combine ingredients provides an efficient method for reducing production time and operator requirements for producing syndiotactic polybutadiene dispersions for downstream compounding.

[0050] The point where the water and emulsifier streams are combined with the reactive cement output can be heated, if desired, to control the temperature drop in the reactive cement stream that occurs when the reactive cement stream is combined with the lower temperature water and emulsifier. A rapid or significant temperature drop in the reactive cement can lead to rapid precipitation of the syndiotactic polybutadiene and / or plugging or fouling in the lines. Pipes may be insulated and heat traced to control the temperature of the resulting premix. Lines providing the supply of the reactive cement and aqueous emulsifier mixture (e.g., slurry) may further be equipped with check valves to ensure the prevention of backmixing and fouling in the supply lines.

[0051] The aqueous emulsifier and reactive cement feed lines may be combined to form a single feed line that connects to the inlet of the colloid mill. The length of the single feed line to the colloid mill should be minimized to avoid the risk of polymer precipitation and line fouling or plugging. In another example, the inlet to the colloid mill may be a tube-in-tube or concentric tube configuration, such that the two streams converge or join together directly or in close proximity to the inlet of the colloid mill to avoid the risk of line plugging or precipitation. A tube-in-tube configuration may include the syndiotactic polybutadiene-containing cement flowing in the center tube and the water and emulsifier flowing in the outer tube, or the reverse configuration may be used.

[0052] The colloid mill may be any suitable mill, such as an Ensight CBT-50 mill. The colloid mill may have adjustable settings, such as the mill gap, or the distance between the outer surface of the rotor and the inner wall of the mill casing. The mill gap setting may range from 0.02 to 2.3 millimeters (mm), 0.05 to 2 mm, 0.1 to 1.5 mm, or 0.25 to 1 mm. The rotor rotation speed may also be adjusted and may range from 700 to 7500 revolutions per minute (rpm), 1000 to 6000 rpm, 1500 to 5000 rpm, or 2000 to 4500 rpm.

[0053] The premix contains at least syndiotactic polybutadiene, one or more polymerization solvents, one or more emulsifiers, and water. The syndiotactic polybutadiene is preferably flowable and may be present dissolved in the polymerization solvent. The syndiotactic polybutadiene is present in the premix in an amount ranging from 2 to 30, 3 to 25, or 4 to 20 weight percent, based on the total weight of the premix. Water is preferably present in the premix in an amount ranging from 30 to 80, 35 to 65, or 40 to 60 weight percent, based on the total weight of the premix. The one or more polymerization solvents may be present in the premix in an amount ranging from 20 to 55, 25 to 50, or 30 to 45 weight percent, based on the total weight of the premix. The one or more emulsifiers may be present in the premix in an amount ranging from 0.05 to 5, 0.1 to 3, or 0.25 to 2 weight percent, based on the total weight of the premix. In another embodiment, the syndiotactic polybutadiene-containing cement, which comprises a polymerization solvent and a syndiotactic polybutadiene, can be present in the premix in a range of 30 to 80, 35 to 65, or 40 to 60 weight percent, based on the total weight of the premix.

[0054] In one or more embodiments, the amount of total emulsifier in the premix can be measured relative to the total content of syndiotactic polybutadiene in the cement or premix. For example, the weight ratio of total emulsifier in the premix to syndiotactic polybutadiene, or the weight ratio of total emulsifier in the premix to the syndiotactic polybutadiene-containing cement incorporated into the premix, can be in the range of 2 to 25, 3 to 20, 4 to 15, or about 5, 8, 10, or 12. In one or more embodiments, the weight ratio of total emulsifier in the premix to syndiotactic polybutadiene is less than 10, less than 8, less than 6, less than 5, less than 4, or less than 3.

[0055] The emulsifier in the premix may be at least one ionic surfactant, for example, at least one sulfonate or sulfate compound. Examples of emulsifiers include alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate, alkyl sulfates such as sodium lauryl sulfate, sodium dodecyl sulfate, and sodium tetradecyl sulfate, ethoxy sulfates such as sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene nonylphenyl ether sulfate, and alkane sulfonates. In other embodiments, examples of suitable types of emulsifiers include, but are not limited to, anionic, nonionic, and cationic surfactants, such as sodium stearate, rosin acid soap, and various fatty acid soaps such as alpha olefin sulfonates.

[0056] The premix is ​​subjected to a mixing step to disperse the syndiotactic polybutadiene (e.g., from the polymerization cement) into the remaining components of the premix to form a uniform mixture. The mixing step can be carried out using mixing equipment known in the art. For example, a vessel or container equipped with a mixer or agitator, such as a mechanical or motorized mixing section, can be used to form the mixture. The mixing step applies shear forces to the mixture that promote distribution of the syndiotactic polybutadiene into smaller particles throughout the mixture. The shear forces can be generated by an in-vessel mixer or in equipment attached to a transfer pipe, such as bypass or recirculation piping in fluid communication with the tank or vessel. In one or more embodiments, low- or high-shear mixers can be utilized to mix the premix and form the dispersion. Non-limiting exemplary equipment includes static mixers, homogenizers, pumps, magnetic stir bars, rotors / stators, agitators, orifice plates, perforated plates, nozzles, venturis, jet mixers, eductors, and static or dynamic cavitation equipment.

[0057] In another example, the premix can be fed (eg, in the form of a stream or flowing through a pipe) into a colloid mill to mix the ingredients and apply shear forces.

[0058] The premix can be mixed for any suitable time to separate and uniformly distribute the syndiotactic polybutadiene in the water and emulsifier. In one example, a premix at an elevated temperature of 60°C to 100°C can be continuously mixed during the mixing process or stage until the mixture or dispersion reaches 20°C to 25°C, or room temperature. The mixing process can be divided into segments as desired, depending on the availability of the particular process or equipment. In another example, the premix can be mixed at a constant elevated temperature or within an elevated temperature range, e.g., a mixing temperature in the range of 60°C to 100°C, and then allowed to cool to about room temperature. In yet another example, the premix can be mixed for 10 minutes to 4 hours, 15 minutes to 2 hours, or 30 minutes, 45 minutes, 1 hour, or 1.5 hours. The mixing time can be adjusted depending on the shear force applied to the premix. For example, the mixing time can be measured by the residence time in a vessel equipped with an agitator or mixing means disposed within the vessel. In another example, mixing time can be measured by passing the mixture through a recirculation loop containing a mixing device (e.g., a pump, static mixer, homogenizer, throttle valve, etc.), taking into account the volume of the recirculation loop and the number of cycles through the loop.

[0059] As the mixture cools during the mixing process, or if the mixture is mixed at a desired temperature and then allowed to cool after mixing, the well-mixed and distributed syndiotactic polybutadiene from the cement solidifies in the mixture to form a dispersion of syndiotactic polybutadiene. The solidified syndiotactic polybutadiene particles can vary in average particle size depending on the length and intensity of the mixing process. In one or more embodiments, the syndiotactic polybutadiene particles can have an average particle size ranging from 0.1 μm to 1,000 μm, 1 μm to 500 μm, 5 μm to 250 μm, or 10 μm to 100 μm, e.g., an average calculated using the largest diameter measured for each particle. In one or more embodiments, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the syndiotactic polybutadiene particles may have an average particle size of less than 10,000 μm, less than 5,000 μm, less than 2,500 μm, or less than 1,000 μm. The presence of an emulsifier in the mixture prevents the formed solid syndiotactic polybutadiene particles from coalescing and sticking together to form agglomerates, so that the formed dispersion is flowable and easily transportable when cooled.

[0060] The formed dispersion can be stored for later use or transferred directly to downstream processes, which can include solvent removal to reduce or completely eliminate the presence of any residual polymerization solvent in the dispersion. The dispersion is processed to be substantially free of the solvent contained in the cement used to prepare the dispersion, and remains fluid at room temperature or in the range of 20°C to 30°C. Thus, the formed dispersion can be stored at low temperatures, reducing the need to keep the cement at high temperatures until the polymerization solvent is removed, thereby ensuring that the syndiotactic polybutadiene does not form coagulated clumps in the cement.

[0061] The dispersion can also be used to prepare rubber compositions, such as those for use as components in vehicle tires. The rubber composition can contain other ingredients known in the art, including, but not limited to, elastomers, fillers, accelerators, curing packages, sulfur, zinc oxide, waxes, processing oils, ozonants, antioxidants, and the like. The liquid components of the dispersion, primarily water and any solvent, can be removed, and the remaining syndiotactic polybutadiene particles and emulsifier can be dried and incorporated into a rubber composition. The liquid components can be removed by, for example, oven drying, vacuum evaporation, spray drying, and the like, as known in the art. The syndiotactic polybutadiene particles and emulsifier (e.g., particle-separate or particle-bound emulsifier) ​​from the dispersion can be incorporated into the components of a rubber composition, for example, in a Banbury mixer, kneader, extruder, and the like, as known in the art.

[0062] The dried syndiotactic polybutadiene particles may contain emulsifier from the dispersion. The weight ratio of emulsifier to syndiotactic polybutadiene in the dispersion can be minimized to reduce the amount of emulsifier present in the dried syndiotactic polybutadiene particles and therefore incorporated into the rubber composition. For example, the dried syndiotactic polybutadiene particles may contain less than 20 wt%, less than 15 wt%, less than 12 wt%, less than 10 wt%, less than 8 wt%, or less than 5 wt%, or when incorporated into the rubber composition, the total amount of emulsifier in the rubber composition can be less than 10 wt%, less than 8 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 1 wt%, less than 0.5 wt%, or less than 0.25 wt%. The total amount of emulsifier present in the dispersion that is transferred to the rubber composition by using dried syndiotactic polybutadiene particles formed from the dispersion is preferably minimized to reduce any adverse effects on the modulus and tan δ of the rubber composition.

[0063] Turning to FIG. 1 , a premix 16 is shown contained in tank 14. The premix is ​​formed by feeding water 10, an emulsifier or blend of emulsifiers 11, and a syndiotactic polybutadiene-containing cement 12 from a polymerization process to tank 14. Water 10, emulsifier 11, and cement 12 may be fed to tank 14 by pumps or suitable transfer devices. In another example, water 10 and emulsifier 11 may be combined and fed to tank 14 as a single feed stream. In this example, water 10 and emulsifier 11 may be preblended in the tank or passed through an in-line mixer or pump to blend the components before being introduced to tank 14. Tank 14 may be equipped with heating means, such as a steam jacket or heating coils, to maintain premix 16 at a temperature above the dissolution temperature of the syndiotactic polybutadiene in cement 12. In one embodiment, the premix 16 is maintained above 60° C. or in the range of 60° C. to 95° C., which also allows for partial desolventization of the polymerization solvent in the cement.

[0064] The premix 16 is subjected to a mixing step, which subjects the premix to mixing and shear forces to form a dispersion. The mixing step can be performed in the tank 14, as shown, using a motorized mixing element 18 mounted within the tank. The mixing element 18 can be located or mounted within the tank 14, or any similar suitable container, as desired. For example, the mixing element can be mounted at the top of the tank, as shown in FIG. 1, or at the bottom. Alternatively, the premix 16 can be mixed to form a dispersion within the tank 14 by transporting the premix 16 through a recirculation loop that includes a mixer. The recirculation loop is in fluid communication with the tank 16 and reintroduces the mixed premix 16 back into the tank 14 after passing through a mixer mounted in-line within the recirculation loop.

[0065] The mixing step of premix 16 may include cooling the mixture formed in tank 14 while mixing by not using a heating means, such as a tank jacket, to maintain the temperature of the tank contents during the mixing step. As premix 16 is mixed and dispersed particles of syndiotactic polybutadiene are formed, heat is transferred through the tank walls and the mixture formed gradually cools during mixing and during its residence time after mixing in tank 14. In another example, the mixing step time may include a portion where the premix is ​​mixed under heated conditions to maintain the temperature of the mixture, and then a second portion where the mixture formed is allowed to cool without heated conditions, either during part of the mixing step, during the time after mixing, or during a combination of both operations.

[0066] During the combined mixing and cooling process, the syndiotactic polybutadiene from the cement solidifies into syndiotactic polybutadiene particles uniformly dispersed in the water, emulsifier, and remaining components of the cement. The mixing process is preferably conducted at a temperature above the dissolution temperature of the syndiotactic polybutadiene in the cement's polymerization solvent; therefore, partial evaporation of the cement components can occur during the mixing process during the formation of a fluid, flowable dispersion of solid syndiotactic polybutadiene particles. The formed dispersion 22 containing syndiotactic polybutadiene particles 21 is transferred to a holding tank 20 for future use or downstream processing, which may include solvent removal or direct incorporation into a tire rubber composition component. Tank 20 may also be equipped with heating means to facilitate further solvent removal or be in fluid communication with a solvent removal system to form a dispersion substantially free of hydrocarbon solvents, such as one or more solvents used in the polymerization of syndiotactic polybutadiene.

[0067] FIG. 2 shows a preformed slurry 34 contained in a tank 36. The preformed slurry is formed by supplying water 30 and an emulsifier or blend of emulsifiers 32 to the tank 36. To prepare the preformed slurry 34, the water 30 and emulsifier 32 undergo a mixing process to achieve a uniformly mixed slurry. The mixing process can be performed within the tank 36 as shown, using a motorized mixing element 38 mounted within the tank. The mixing element 38 can be positioned or mounted within the tank 36, or any similar suitable container, as desired. For example, the mixing element can be mounted at the top of the tank, as shown in FIG. 2, or at the bottom.

[0068] Preformed slurry 34 is supplied from tank 36 to the inlet of colloid mill 50 by transfer line 42. A check valve 44 may optionally be installed in transfer line 42, for example, at or near the inlet to the mill, to prevent backflow and premature mixing with the syndiotactic polybutadiene-containing cement 40 from the polymerization process. To control or minimize the effect of preformed slurry 34 on reducing the temperature of the syndiotactic polybutadiene-containing stream, the tank and / or transfer line 42 may be heated, for example, with electrical tracing or jacketing, to maintain the desired temperature.

[0069] A syndiotactic polybutadiene-containing stream 40, such as cement from a polymerization process, is also fed through a transfer line (e.g., a pipe) to the inlet of the colloid mill 50. A check valve 46 may optionally be installed in the transfer line 40, for example, at or near the inlet to the mill, to prevent backflow and premature mixing with the preformed slurry 34 in the transfer line 42. By combining the transfer lines 40, 42 at or near the inlet to the colloid mill 50 to form a premix, the preformed slurry stream and the syndiotactic polybutadiene-containing stream are passed through the mill, where the mill applies shear forces to the streams, mixing them and forming a dispersion of syndiotactic polybutadiene particles. Although not shown, the transfer lines 40, 42 can be combined in a concentric tube arrangement downstream of the optional check valves 44, 46, such that the preformed slurry flows in an outer tube surrounding the syndiotactic polybutadiene-containing stream flowing in the inner tube before being fed together to the inlet of the mill 50.

[0070] The colloid mill 50 includes a rotor rotating inside a stationary stator, such that the premix is ​​passed through the gap between the rotating rotor and the stationary stator, applying shear to the premix to promote mixing and dispersion of the polymer particles. The gap between the outer surface of the rotor and the inner wall of the mill casing or the inner wall of the stator surrounding the rotor is in the range of 0.02 to 2.3 millimeters (mm), and the rotor rotating within the stator can operate at a speed in the range of 700 to 7500 revolutions per minute (rpm) or 2000 to 4500 rpm. Before entering the inlet of the colloid mill, the premix is ​​preferably at a temperature in the range of 70°C to 100°C.

[0071] In another embodiment, colloid mill 50 can optionally be equipped with a heating means, such as a steam jacket or heating coils, to maintain the premix at a temperature above the dissolution temperature of the syndiotactic polybutadiene in cement 40. In one example, the premix is ​​maintained above 60°C or in the range of 70°C to 100°C, which can also effect partial desolventization of the polymerization solvent in the cement. The formed dispersion containing syndiotactic polybutadiene particles 57 is fed via transfer line 54 to tank 56, which may also be thermally controlled to maintain the temperature of the dispersion for future use or downstream processing. Downstream processing can include solvent removal or direct incorporation into a tire rubber composition component. Tank 56, which stores dispersion 58, can also be equipped with a heating means or in fluid communication with a solvent removal system to facilitate further solvent removal to form a dispersion substantially free of hydrocarbon solvents, such as one or more solvents used in the polymerization of syndiotactic polybutadiene.

[0072] The dispersion can be preheated in a vessel or desolventizer to form a product for incorporation into a rubber composition. The temperature in the desolventizer can be maintained above the boiling point of the polymerization solvent but below the boiling point of the water and emulsifier mixture, for example, in the range of 60°C to 95°C, or 65°C to 80°C. The substantially solvent-free dispersion can be separated and vacuum dried for further compounding into a rubber composition. [Example]

[0073] The following examples illustrate specific and exemplary embodiments and / or embodiment features of the present disclosure. The examples are provided for illustrative purposes only and should not be construed as limiting the present disclosure. Many modifications to these specific examples are possible without departing from the spirit and scope of the embodiments of the present disclosure. More specifically, the specific solvents, reactive compounds, emulsifiers, rubber composition components, and other components used in the examples should not be construed as limiting, as other components may be substituted as long as they are consistent with the disclosure in the detailed description. That is, the specific components in the compositions and their respective amounts and relative amounts should be understood to apply to the general content of the detailed description.

[0074] Example 1 Polymerization of syndiotactic polybutadiene A 2-gallon, nitrogen-purged reactor equipped with an agitator was charged with approximately 20% by weight of the butadiene / hexane mixture and enough anhydrous hexane to prepare 5 pounds of a 15% by weight butadiene solution. A hexane solution containing 0.28 mL of iron(III) 2-ethylhexanoate and 0.37 mL of bis(2-ethylhexyl) phosphite was added to the reactor, followed by 5.6 mL of tri-n-butylaluminum (0.68 M in hexane) diluted with hexane. The reactor jacket was heated to 82.2°C. After 23 minutes, the batch temperature of the reaction mixture peaked at 109.7°C. When the batch temperature cooled to 82.2°C, 6.8 g of 2,6-di-tert-butyl-4-methylphenol (approximately 2 phr) and 2.5 pounds of cyclohexane were added to the reactor to produce a cement containing 10% by weight syndiotactic polybutadiene. This cement was used in the following examples.

[0075] Example 2 Syndiotactic polybutadiene dispersion To a 750 mL glass bottle containing a stir bar, water and sodium lauryl sulfate (SLS) were added in the amounts shown in Table 1. The bottle was sealed and placed in a 100°C oven for 30 minutes. The 71°C syndiotactic polybutadiene polymer cement prepared in Example 1 was then added dropwise from the reactor to the bottle in the amount shown in Table 1. The bottle was then placed on a stir plate, and stirring was set to the maximum speed that maintained a stable vortex until the bottle was completely cooled to room temperature. For all Samples 2-6, the resulting dispersions were fluid dispersions consisting of non-coalesced particles of cement-derived syndiotactic polybutadiene in water that could be poured from the bottle without issue.

[0076] [Table 1]

[0077] Example 3 Syndiotactic polybutadiene dispersion 13 g of sodium lauryl sulfate (approximately 5 wt. % relative to the syndiotactic polybutadiene) and 5 L of water were added to a small steam desolventizer bucket, and the mixture was heated to 60°C using the steam supply to the desolventizer. The syndiotactic polybutadiene cement prepared in Example 1 was maintained at 60°C in a reactor with a steam-traced feed line connected to the outlet. The steam-traced feed line was set to 65.5°C, and the syndiotactic polybutadiene cement was transferred to the small steam desolventizer bucket by pressure differential. When the cement addition was complete, the agitator was turned on and adjusted to the highest speed possible without causing overflow. Agitation continued for several hours until the mixture cooled to room temperature. Microfouling was observed as a result of partial desolventization of the syndiotactic polybutadiene cement during the initial cement addition. By mixing the syndiotactic polybutadiene cement with water and an emulsifier, a dispersion of small particles of cement-derived syndiotactic polybutadiene in water was formed, which then had improved flowability and could be easily poured from the equipment bucket.

[0078] Example 4 Rubber composition comprising dispersion-derived syndiotactic polybutadiene and an emulsifier The effect of emulsifiers from syndiotactic polybutadiene dispersions was investigated when dispersion-forming syndiotactic polybutadiene particles were used in rubber compositions. The emulsifier used in the syndiotactic polybutadiene dispersion of Example 2 was tested. The solvent from the syndiotactic polybutadiene cement of Example 1 was removed under vacuum, and the syndiotactic polybutadiene particles were heated before being incorporated into the rubber composition. To evaluate the effect of sodium lauryl sulfate, various amounts of emulsifier relative to the amount of syndiotactic polybutadiene were added to the rubber composition during the mixing stage. Additionally, a control rubber composition was prepared without sodium lauryl sulfate. To simulate the addition of sodium lauryl sulfate as a component of the syndiotactic polybutadiene particles, the polymer and sodium lauryl sulfate were added to the mixer and mixed for a short period of time, after which the remaining ingredients were added and the rubber composition was vulcanized. The compound formulations are shown in Table 2.

[0079] [Table 2]

[0080] The compound properties of the rubber compositions are summarized in Table 3 below. Some differences in the compound properties were observed. Higher loadings of sodium lauryl sulfate (SLS) showed a greater impact. For example, an increase in ΔG' at 60°C was observed with the addition of sodium lauryl sulfate, and a decrease in M200 was observed. A corresponding increase in tan δ at 60°C was also observed. These effects were reduced at the lowest loading studied, 1 wt% sodium lauryl sulfate. To minimize any impact on the compound properties of the rubber compositions, the amount of emulsifier used to form the dispersion can be reduced.

[0081] [Table 3]

[0082] Example 5 Polymerization of syndiotactic polybutadiene A 20-gallon reactor was charged with 36 pounds of a hexane / butadiene mixture as a 15% by weight butadiene solution. The butadiene solution was stirred and heated to 125°F. Once the reactor was at temperature, the catalyst was charged. The catalyst was charged in two stages. The first stage contained 1.129 mL of iron(III) 2-ethylhexanoate (0.964 M in mineral oil), 1.486 mL of bis(2-ethylhexyl) phosphite, and 50 mL of hexane, followed by the second stage containing 22.413 mL of tri-n-butylaluminum (0.68 M in hexane) diluted with hexane. The reactor jacket was raised to 180°F to allow for a peak exotherm. A peak was observed at 202°F 188 minutes after the catalyst charge. The reactor was allowed to cool to approximately 180°F to confirm completion of the reaction. After cooling, 27.2 g of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene and 13.6 g of tris(nonylphenyl)phosphite were added to the reactor along with 10 pounds of cyclohexane to give a 10 wt % butadiene solution. The contents were reheated to 190°F in preparation for dispersion as described in the following examples.

[0083] Example 6 Example of a distributed process Prior to and / or during the polymerization of the syndiotactic polybutadiene of Example 5, a slurry of water and emulsifier was prepared and charged to a slurry tank. Calfax DB45 (emulsifier) ​​was weighed at 5 phr, or 68.1 g, relative to the syndiotactic polybutadiene polymer. Sufficient 60 pounds of water was added to maintain the desired flow rate of 3 pounds per minute for 20 minutes. A 50% excess slurry was prepared, maintaining the same ratio, to allow for additional run time in case of slower or more imprecise flow rates. The slurry tank was sealed and brought to a regulated pressure of 60 psi.

[0084] The water and emulsifier slurry preparation described above was also made using the same process, except that the emulsifier was added at 2.5 phr of syndiotactic polybutadiene polymer instead of 5 phr. The lower emulsifier content of this slurry can reduce any degradation of final compound performance properties.

[0085] Prior to operation, the colloid mill was set to the desired milling gap of 0.45 inches. To operate the mill, the slurry flow was initiated and a flow rate of 3 lbs / min was established. The colloid mill was started and the speed set to 2880 rpm. Steam heating was also started on the heat-traced section of the syndiotactic polybutadiene cement line and set to 220°F to ensure good flow of cement into the mill where it was mixed with the slurry. The flex hose from the colloid mill outlet was placed into a receiving bucket through a custom lid fitted with exhaust ventilation to prevent the release of large amounts of hydrocarbon solvent. The receiving bucket also contained approximately 1 gallon of isopropyl alcohol to kill any residual active catalyst present in the syndiotactic polybutadiene cement.

[0086] The reactor pressure in Example 5 was increased to 55-60 psi, and the syndiotactic polybutadiene cement was fed into the colloid mill. The flow of syndiotactic polybutadiene cement from the reactor was then initiated by opening the reactor's discharge valve, while the pressure differential created by the pressurized reactor forced the syndiotactic polybutadiene cement out the discharge valve. The cement flow was manually controlled by reading the flow rate and adjusting the discharge valve. The cement flow rate was stabilized at approximately 1.5 lbs / min. The resulting product stream exiting the colloid mill was a syndiotactic polybutadiene polymer-hexane cement mixture with an aqueous surfactant coating throughout the cement. Contact with water from the slurry also reduced the temperature of the syndiotactic polybutadiene cement phase below its melting point, but sufficient flow rate and shear of the material was maintained to avoid solidification.

[0087] The following examples are summarized in Table 4, along with various settings for the ratio of syndiotactic polybutadiene cement to emulsifier-containing aqueous slurry. Samples 1-4 in Table 4 demonstrate excellent desolventization properties, as described in the process below. In Sample 5, the amount of emulsifier added was reduced to minimize the impact on the compound's properties. The process for Sample 5 at the settings shown failed to form a pumpable dispersion product, and therefore the subsequent steam desolventization step used for Samples 1-4 was not performed. Therefore, data on the actual flow rate is not shown for Sample 5, nor is an analysis of the steam desolventization efficiency, as the production of a dispersion sample was unsuccessful at this level of emulsifier and the selected process settings.

[0088] [Table 4]

[0089] Example 7 Example of Steam Desolventization of Dispersion Four to five gallons of DI water were added to the steam desolventizer along with 20 g of Polycoat LCD. The water was stirred to disperse the Polycoat and heated to an operating temperature of 180°F to 200°F while monitoring with a Thermo-IR thermometer. A dispersion sample collected in Example 6 was weighed to determine the exact weight of water, cement, and emulsifier. The entire contents of the sample were placed in a payliner and agitated with an air-pressure propeller. The agitated sample was added to the steam desolventizer while monitoring the desolventizer level and temperature to avoid overfilling.

[0090] After desolvation was complete and cooled, the dispersions were evaluated by measuring the weight percent of the "bulk" and "fouling" phases formed during desolvation. These are believed to represent the free, agitated dispersion material in the water bath and any material trapped inside the desolvation apparatus, respectively. Since water was still entrapped within the sample, the weight percent of fouling was recorded as the % Wet Fouling. Both the bulk and dry materials were then vacuum dried at 50°C and approximately 30 inHg for 10 hours. The weights of both of these phases were then recorded again once dry and recorded as the % Dry Fouling. These values ​​are shown in Table 5 below for Samples 1-4.

[0091] [Table 5]

[0092] Example 8 Mixing study The effect of the dispersion of Example 6 was tested to determine its suitability for further consideration in rubber composition compounding. Dispersion samples prepared as described above were subjected to testing in compounding tread compositions shown as Compound 3 in Table 6 below. Tread Compounds 1 and 3 each contained no syndiotactic polybutadiene and a standard syndiotactic polybutadiene not added as a dispersion as prepared in the above examples. All amounts are given in phr. A summary of the properties of the compounded compounds is shown in Table 7.

[0093] [Table 6]

[0094] The formulations in Table 6 were prepared by mixing in a tangential mixer. The masterbatch stage began at 100°C at 60 rpm and mixed for 5.0 minutes, or until a temperature drop of 155°C was reached. The final stage was at 60°C at 40 rpm for 2.5 minutes, or until a temperature drop of 110°C was reached. The raw rubber formulations were cured at 150°C for 25 minutes to prepare specimens for physical testing, as shown in Table 7 below.

[0095] [Table 7]

[0096] As can be seen in Table 7, the overall tensile strength properties of M300 modulus at 25°C and 100°C decreased when dispersed syndiotactic polybutadiene was used compared to standard syndiotactic polybutadiene.

[0097] While various aspects and embodiments of the tires, compositions, and methods have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes only and are not intended to limit the true scope and spirit of the present invention, as indicated by the appended claims.

Claims

1. a. syndiotactic polybutadiene particles; b. Water; c. an emulsifier.

2. 10. The syndiotactic polybutadiene dispersion of claim 1 further comprising one or more hydrocarbon polymerization solvents.

3. 10. The syndiotactic polybutadiene dispersion of claim 1, wherein the dispersion is substantially free of hydrocarbon solvents.

4. 2. The syndiotactic polybutadiene dispersion of claim 1, wherein the emulsifier is a sulfonate compound or a sulfate compound.

5. 5. The syndiotactic polybutadiene dispersion of claim 4, wherein the sulfate compound is sodium lauryl sulfate, sodium tetradecyl sulfate, sodium dodecyl sulfate, and combinations thereof.

6. 2. The syndiotactic polybutadiene dispersion of claim 1, wherein the weight ratio of said emulsifier to said syndiotactic polybutadiene particles in said dispersion ranges from 2 to 20.

7. 10. The syndiotactic polybutadiene dispersion of claim 1, wherein the total amount of emulsifier present in the dispersion ranges from 0.05 to 3 weight percent based on the total weight of the dispersion.

8. 10. The syndiotactic polybutadiene dispersion of claim 1, wherein the syndiotactic polybutadiene particles present in the dispersion range from 2 to 20 weight percent based on the total weight of the dispersion.

9. 10. The syndiotactic polybutadiene dispersion of claim 1, wherein the water present in the dispersion ranges from 35 to 65 weight percent based on the total weight of the dispersion.

10. 10. The syndiotactic polybutadiene dispersion of claim 1, wherein the syndiotactic polybutadiene particles of the dispersion are uniformly distributed solid particles and the dispersion is flowable at room temperature.

11. 10. A rubber composition comprising the syndiotactic polybutadiene particles of the syndiotactic polybutadiene dispersion of claim 1 and the emulsifier, wherein the rubber composition is substantially free of the water of the dispersion.

12. 12. The rubber composition of claim 11, wherein the rubber composition is substantially free of any polymerization solvent present in the syndiotactic polybutadiene dispersion of claim 1.

13. The rubber composition according to claim 11, further comprising 0.1 to 3 parts by weight of the emulsifier based on 100 parts by weight of the rubber component of the rubber composition.

14. The rubber composition according to claim 11, further comprising 1 to 30 parts by weight of the syndiotactic polybutadiene particles based on 100 parts by weight of the rubber component of the rubber composition.

15. 1. A method for preparing a syndiotactic polybutadiene dispersion, comprising: a. combining syndiotactic polybutadiene cement with water and an emulsifier to form a premix; b. subjecting the premix to a mixing step to form a dispersion; c) cooling the dispersion of step b to solidify the syndiotactic polybutadiene into particles.

16. 16. The method of claim 15, wherein the mixing step comprises applying shear forces to the premix.

17. 16. The method of claim 15, wherein the premix is ​​at a temperature greater than 60°C at the start of the mixing step of step b.

18. 16. The method of claim 15, wherein the weight ratio of the emulsifier to the syndiotactic polybutadiene in the cement ranges from 2 to 20.

19. The premix contains the following amounts: a. the syndiotactic polybutadiene present in the premix is ​​in the range of 2 to 20 weight percent, based on the total weight of the premix; b. the water present in the premix is ​​in the range of 35 to 65 weight percent based on the total weight of the premix; and c) the total amount of the emulsifier present in the premix is ​​in the range of 0.05 to 3 weight percent based on the total weight of the premix.

20. 16. The method of claim 15, wherein the syndiotactic polybutadiene particles of the dispersion of step c are uniformly distributed solid particles and the dispersion is flowable at room temperature.

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