Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
  • B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
  • B29B7/40—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft
  • B29B7/42—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft with screw or helix
  • B29B7/421—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft with screw or helix with screw and additionally other mixing elements on the same shaft, e.g. paddles, discs, bearings, rotor blades of the Banbury type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/02—Making granules by dividing preformed material
  • B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/04—Particle-shaped
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/397—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using a single screw
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/625—Screws characterised by the ratio of the threaded length of the screw to its outside diameter [L/D ratio]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/68—Barrels or cylinders
  • B29C48/681—Barrels or cylinders for single screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/68—Barrels or cylinders
  • B29C48/685—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads
  • B29C48/686—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads having grooves or cavities
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/68—Barrels or cylinders
  • B29C48/685—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads
  • B29C48/687—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads having projections with a short length in the barrel direction, e.g. pins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92504—Controlled parameter
  • B29C2948/9258—Velocity
  • B29C2948/9259—Angular velocity

Definitions

• This invention relates to a process for pelletizing elastomeric anionically polymerized polymers.
• Elastomeric polymers of styrene and butadiene or isoprene are anionically polymerized in an organic solvent. Such polymers are also often hydrogenated while in the solvent.
• the final step in the production of these polymers requires removing the solvent from the polymer/solvent mixture/slurry/suspension, usually referred to as the polymer cement, to produce dry material which can be packaged. This final processing step is often referred to as "finishing" the polymer.
• These polymers are generally produced as a crumb that is sometimes difficult to handle and is many times undesirably sticky as well.
• Pellets of these commercial thermoplastic polymers are formed with melt extruders, often twin screw extruders, which carry out their function by melting the polymer and extruding it through a die where it is chopped into small pellets.
• Many of the polymers of this invention are high molecular weight materials and highly elastic materials. When these polymers are processed in twin screw melt extruders, they tend to generate enough shear heat to cause significant degradation. Degradation causes the polymer properties to suffer and is a significant disadvantage .
• Elastomeric anionic polymers of styrene and butadiene or isoprene, including polyisoprene star polymers are anionically polymerized as in the past. This processing may also incorporate hydrogenation if desired.
• the polymer is produced in crumb form. The dried polymer crumb is then converted to pellets via solid state extrusion. The polymer crumb is extruded in a single screw extruder which has a longitudinally grooved barrel and has pins extending into the barrel transverse to the flow of the polymer.
• the extruder has a length to diameter (L/D) ratio of 10:1 or less, preferably 8:1 or less, and is operated at 30 to 100 rpm, preferably 40 to 60 rpm.
• the temperature of the polymer in the extruder must be sufficient to agglomerate or melt the polymer but the temperature should not exceed the degradation temperature of the polymer.
• the solid state extrusion is carried out at 200 °C or less and most preferably 160 °C or less.
• agglomerate it is meant that the polymer is soft enough and sticky enough to stick together but has not yet passed through the glass transition temperature which is the point at which the polymer melts.
• Polymers of the type described herein are known to degrade at temperatures of 300 °C and higher so it is important that the temperature in the single screw extruder be less than that. However, it is possible that higher localized temperatures can occur in the extruder so it is highly preferred that the temperature in the extruder be 200 °C or less. It is most preferred that the temperature be 160 °C or less to minimize localized temperature peaks which can cause degradation of the polymer at those locations.
• the barrel of the single screw extruder has longitudinal grooves and pins extending into the barrel transverse to the flow of the polymer.
• L/D length to diameter
• the speed of the extruder screw should be from 30 to 100 rpm for extruders with an L/D ratio of from 2:1 to 10:1. If the L/D ratio is smaller, then the speed of the screw can be lower. Again, the goal is to provide sufficient mixing without heating up the polymers to a temperature where it degrades .
• the polymers suitable for finishing by the process of this invention include hydrogenated homopolymers and copolymers of diolefins containing from 4 to 12 carbon atoms, hydrogenated copolymers of one or more conjugated diolefins and one or more monoalkenyl aromatic hydrocarbons containing from 8 to 16 carbon atoms.
• the base polymer may be of a star or linear structure.
• Hydrogenated polymers may be hydrogenated selectively, completely or partially. Hydrogenated polymers of conjugated diolefins and copolymers of conjugated diolefins and monoalkenyl arenes are preferably hydrogenated such that greater than 90% of the initial ethylenic unsaturation is removed by hydrogenatio . Preferably, the hydrogenated polymers are substantially free of ethylenic unsaturation. Selective hydrogenation refers to processes that hydrogenate a substantial portion of the ethylenic unsaturation and a substantial portion of the initial aromatic unsaturation is left unhydrogenated .
• a hydrocarbon polymer substantially free of ethylenic unsaturation will be a hydrocarbon polymer containing, on average, less than 10 carbon-carbon ethylenic double bonds per polymer chain. Polymers containing more than this amount of ethylenic unsaturation will, under certain conditions, exhibit excessive cross-linking during a functionalization reaction when the functionalization is completed in a blending apparatus capable of imparting high mechanical shear .
• Useful hydrocarbon polymers include those prepared in bulk, suspension, solution or emulsion. As is well known, polymerization of monomers to produce hydrocarbon polymers may be accomplished using free-radical, cationic and anionic initiators or polymerization catalysts. A wide range of molecular weight polymers can be processed as described herein. In general, the higher the molecular weight of the polymer, the more likely it is that degradation of the polymer will occur in conventional melt processing. Thus, this invention is especially advantageous for higher molecular weight polymers. In general, polymers with weight average molecular weights of between 100,000 and 1,200,000 may be processed according to this process.
• the weight average molecular weights, as used herein, for linear anionic polymers refers to the weight average molecular weight as measured by Gel Permeation Chromatography ("GPC") with a polystyrene standard.
• GPC Gel Permeation Chromatography
• star polymers the weight average molecular weights are determined by light scattering techniques.
• melt flow index (MFI) of Polymer A, which is a hydrogenated polyisoprene star polymer containing 6% by weight polystyrene, at temperatures up to 270 °C. Even at these high temperatures and with weight as high as 9.9 kg, the material was extremely difficult to press through the melt flow die hole 0.2 mm (.008 inch die) . Additional testing using a capillary rheometer at equally high temperatures yielded poor results.
• the 57 mm (2.25 inch) extruder was fitted with a variable speed cutter to pelletize the extruded strands. Runs were carried out at 35 rpm. No external heating or cooling was applied. The temperature of the polymer due to frictional heating was 150 °C . All materials tested were extruded successfully with no degradation. It was more difficult to achieve a homogeneous strand with
• Polymer C which is a linear hydrogenated block copolymer of styrene and isoprene. Some strands appeared to have a "dust" of crumb along the outer edge indicating possible slippage along the barrel cavity and insufficient mixing. This disappears as extruder temperatures rise.
• KRATON is a trademark.
• KRATON G1651, G1650, G1652, and research grade GRP-6917 were successfully pelletized after experimenting with different die designs. All of these polymers are manufactured by Shell Chemical Company and are block copolymers of styrene and/or hydrogenated isoprene and/or butadiene .
• Example 3
• the cooler was equipped with a fan that delivered room temperature air at a rate up to 71 m ⁇ /n ⁇ n (2500 cu ft/min.) .
• a temperature probe was placed approximately halfway down the barrel. The process appeared to reach steady state with a measured barrel temperature of 150 °C. This temperature is due to the shear heating of the material. No external heating or cooling was applied. Pellets leaving the cooler were at a temperature of approximately 80 °C. No polymer degradation was observed in samples taken throughout the run.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

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• 1999
  • 1999-05-06 US US09/306,123 patent/US6458300B1/en not_active Expired - Fee Related
  • 1999-05-14 TW TW088107869A patent/TW408060B/zh active
  • 1999-05-27 CA CA002332923A patent/CA2332923A1/en not_active Abandoned
  • 1999-05-27 DE DE69923972T patent/DE69923972T2/de not_active Expired - Fee Related
  • 1999-05-27 RO ROA200001162A patent/RO120181B1/ro unknown
  • 1999-05-27 WO PCT/EP1999/003726 patent/WO1999061214A1/en not_active Ceased
  • 1999-05-27 CN CNB998066834A patent/CN1191922C/zh not_active Expired - Fee Related
  • 1999-05-27 AU AU43714/99A patent/AU4371499A/en not_active Abandoned
  • 1999-05-27 BR BRPI9910691-4A patent/BR9910691B1/pt not_active IP Right Cessation
  • 1999-05-27 KR KR1020007013186A patent/KR100632024B1/ko not_active Expired - Fee Related
  • 1999-05-27 EP EP99926469A patent/EP1089860B1/en not_active Expired - Lifetime
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• 2000
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