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WO2001090240A1 - Procede de production de polymeres finement divises - Google Patents

Procede de production de polymeres finement divises Download PDF

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Publication number
WO2001090240A1
WO2001090240A1 PCT/US2001/014732 US0114732W WO0190240A1 WO 2001090240 A1 WO2001090240 A1 WO 2001090240A1 US 0114732 W US0114732 W US 0114732W WO 0190240 A1 WO0190240 A1 WO 0190240A1
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WO
WIPO (PCT)
Prior art keywords
polymer
dispersion
finely divided
reactor
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2001/014732
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English (en)
Inventor
Evan Koslow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koslow Technologies Corp
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Koslow Technologies Corp
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Filing date
Publication date
Application filed by Koslow Technologies Corp filed Critical Koslow Technologies Corp
Publication of WO2001090240A1 publication Critical patent/WO2001090240A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C08J3/05—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media from solid polymers

Definitions

  • This invention relates to polymer dispersions useful for binders and thermoplastic applications. More particularly, it relates to the process of producing polymer dispersions by mixing polymer powder with water and surfactant to form a slurry and pumping the slurry into a dispersion reactor to form finely divided polymers.
  • Finely divided polymeric particles are useful for a wide range of applications, including as binders in composite carbon block filter elements, and in other thermoplastic applications.
  • thermoplastic polymers in finely divided form have found use in a number of other commercial applications where it is either impossible or inconvenient to utilize the conventional cube or pellet forms.
  • powdered themoplastic polymers in dry form have been used to coat articles by dip coating in either a static or fluidized bed, by powder coating wherein the powder is applied by spraying or dusting, and by flame spraying.
  • thermoplastic powders have been applied as coatings by roller coating, spray coating, slush coating, and dip coating to substrates such as metal, paper, paper board, and the like.
  • Finely divided polymers have also been widely employed in conventional powder molding techniques. Other important applications of these polymer powders include paper pulp additives, mold release agents for rubber, additives to waxes, paints, polishes, binder for woven fabrics, and the like.
  • thermoplastic Polymers generally employ the cubes or pellets, which are obtained directly from the synthesis process. These processes are of three main types, i.e., mechanical grinding, solution and dispersion.
  • thermoplastic polymers have been manufactured by extruding polymers into a high-shear environment containing a mixture of water and surfactant held at elevated temperature and pressure. Under these process conditions, the polymer forms a dispersion of fine droplets. This dispersion can be cooled to convert these polymeric droplets into solid particles, which are separated from the water- surfactant mixture through conventional washing and drying steps.
  • U.S. Patent No. 3,432,483 a method of continuously producing finely divided polymers.
  • the process consists of introducing the polymer and water-surfactant mixture into a dispersion zone by means of a conventional extruder and dispersing the polymer into a water-surfactant mixture at elevated temperature and pressure, (i.e., at a temperature above the melting point of the polymer and at a pressure sufficient to maintain the water in an aqueous state), agitating the dispersion to achieve a reduction in the size of polymer droplets within the mixing zone, and subsequent cooling of the dispersion to form solid particles of finely divided polymer. These particles are separated from the water-surfactant solution by filtration washing, and drying.
  • the typical method for the introduction of the polymer into the process consists of direct extrusion of liquid polymer.
  • Warner et al. in U.S. Patent No. 4,123,403 describe a similar process consisting of producing a mixture of water and surfactant and dispersing a continuous heat-plasticated polymer phase into this solution.
  • Warner et al. apply shear to the mixture while sustaining laminar flow through the use of a special reactor and rotor. In this system, the applied shear and the addition of water produces a discontinuous polymer phase, which can be cooled to produce solid polymer particles that are highly uniform and of small size.
  • Broehng et al. in U.S. Patent No.4,252,969 describe a refinement of U.S. Patent No.3, 432,483 (Peoples), wherein a particle-size controlling amount of alkanolamide surface active agent is used to provide improved control and range of particle size.
  • the polypropylene is a vis broken polypropylene polymer with a melt flow greater than 1. In most cases, the polymer melt flow is increased through prior reaction with organic peroxides in a conventional plastics extruder.
  • Ondrus et al. in U.S. Patent Nos. 5,338,609 and 5,336,731, and Heimberg et al. in U.S. Patent No.5,209,977 describe partially crosslinked olefin copolymer microfine powders with low (less than 1) melt flow rates.
  • the dispersion is produced by the process described in U.S. Patent No. 3,432,483 (Peoples), but with olefins functionalized to contain unsaturated alkoxysilanes and through the addition of a catalyst that promotes crosslinking of the polymer during the dispersion process.
  • the Peoples process operates best with high melt flow materials, the in-situ crosslinking of the polymer allows the final product to have fractional melt flow.
  • the unique process according to the present invention reduces cost over conventional processes by eliminating the capital- intensive extruder equipment.
  • the present invention readily disperses the polymer in the dispersion reactor resulting in the reduced reactor times, and higher yields and product quality of the finely divided polymers.
  • the present invention greatly simplifies the polymer dispersion process because unlike the extruder process, the equipment of the present invention requires no special expertise to operate.
  • the present invention also provides many additional advantages which shall become apparent as described below.
  • the present invention relates to the production of finely divided polymers.
  • Raw polymer is either purchased as reactor-grade powder or ground into a coarse powder. This coarse powder is mixed with water and a surfactant to form a slurry mixture.
  • the slurry mixture may be pre-heated in a heat exchanger and introduced into the reactor using a high-pressure pump.
  • the polymer powder and water-surfactant slurry mixture is rapidly heated in the reactor while undergoing shear.
  • the polymer powder rapidly disperses into fine droplets under these process conditions.
  • the emulsion is cooled to produce fine particles in the water-surfactant mixture.
  • the finely divided polymer can thereafter be substantially separated from the water-surfactant mixture and dried.
  • Figure 1 is a schematic diagram of the polymer dispersion process according to the present invention.
  • the polymer dispersion process of the present invention is illustrated in Fig. 1.
  • Bulk polymer is obtained as either pellets, reactor-grade powder, or in other conventional physical forms and placed in raw polymer tank 4. If required, the polymer is subjected to grinding such as in a conventional polymer disk grinding mill 6 to reduce the size of the polymer particles to less than 20 mesh, preferably to less than 50 mesh.
  • the polymer is then stored in coarse polymer powder holding tank 8. This coarse polymer powder is then fed through feed control valve 10 to eductor 12 where it is mixed with a water-surfactant mixture supplied from water-surfactant holding tank 14.
  • the resulting polymer slurry from eductor 12 is then pumped through a high-pressure slurry pump 16 to heat exchanger 18.
  • Dispersion reactor 20 is held at elevated temperatures above the melting point of the polymer, and at elevated pressures so that the water in the reactor is in the aqueous state.
  • the polymer is rapidly heated to a temperature above the melting point of the polymer or maintained at the elevated temperature provided by heat exchanger 18. This temperature is usually 20-75°C above the melting point of the polymer.
  • the powder is liquefied, and under the influence of shear, droplets of polymer are reduced in size.
  • the final size of the polymer droplets is related to the temperature within the reactor, the melting point of the polymer, the melt index of the polymer, the selecting of surfactant and surfactant concentration, and applied rate of shear.
  • those droplets are solidified into solid particles by cooling the slurry or discharging the contents of dispersion reactor 20 into a cooled heat exchanger 18. Once the slurry has cooled significantly below the melting point of the polymer, the polymer powder becomes stable and will no longer coalesce or agglomerate into larger particles.
  • Solids-liquid separation belt filter unit 24 has a drain subunit 24a which drains excess water and surfactant, followed by wash subunit 24b executing one or more wash cycles, and thereafter followed by vacuum dry subunit 24c which removes the bulk of the residual wash fluid.
  • the water-surfactant mixture collected from the drain 24a of the solids-liquid separation belt filter unit 24 is directed back to the polymer slurry process through recycle pump 26 to surfactant-water holding tank 14.
  • the wash fluid from wash subunit 24b is accumulated in wash water holding tank 28 and reprocessed using processes such as ultrafiltration or reverse osmosis unit 32. Once the wash fluid surfactant has been concentrated back to the original target concentration specified for the slurry process, the mixture is returned through recycle pump 26 to surfactant-water holding tank 14 for use in the slurry process.
  • the water separated by these membrane processes may be recycled for future wash applications or vented to a drain.
  • the moist polymer powder cake is ejected from the belt filter, sometimes with the assistance of air jets projecting from compressor 54 disposed below the belt.
  • Fused silica from fused-silica tank 50 and fused silica feeder 52 may be mixed with the damp polymer powder to improve the free flow properties of the dry powder.
  • the amount of fused silica is about 0.1 to 2.0 wt. % of the dried polymer powder.
  • the airborne damp polymer powder is then subjected to drying using a high-velocity air drier cyclone 34 or other suitable drying equipment (flash drier).
  • flash drier suitable drying equipment
  • reactor-grade powders are produced by certain slurry-reactor processes used for the production of polyethylene and are sold under, for example, the trade name of EscoreneTM by EXXON Chemical Company. Such materials are usually linear low-density polyethylene (LLDPE) or similar polymers.
  • LLDPE linear low-density polyethylene
  • reactor-grade powders can be further enhanced by grinding. For example, reactor-grade powders are often sold as powders averaging 300 micrometers in diameter. Passing these powders through disc grinder 6 can reduce the average particle size to 140 micrometers without significant cost and at a high throughput.
  • These 140 micrometer particles can be easily reduced to an average particle size of 10 to 20 micrometers in a subsequent slurry dispersion process outlined above.
  • the presence of up to 5% by weight of particles greater than 140 micrometer in diameter in the final product is generally not considered unacceptable for most applications.
  • the polymers suitable for this invention include any polymer whose decomposition temperature is somewhat higher then its melting point temperature and less than the critical temperature of water.
  • Preferred polymers which are suitable for this invention are polyolefins, vinyls, olefin-vinyl copolymers, olefin-allyl copolymers, polyamides, acrylics, polystyrene, polyesters, flurocarbons, and the like.
  • the surfactants used in this invention are typically water soluble, non-ionic surfactants such as block polymers of ethylene oxide and propylene oxide.
  • Other suitable surfactants are disclosed in U.S. Patent 3,432,483 which is fully incorporated herein by reference.
  • Dispersion reactor 20 is equipped with means to impart shear along the length of dispersion reactor 20. Shear is applied along the length of dispersion reactor 20 by use of an elongated shaft having a small clearance with the reactor wall or using a series of individual high-shear elements in dispersion reactor 20 which is driven by motor 48.
  • the design of dispersion reactor 20 limits axial dispersion. This is accomplished either through the use of a narrow gap between a central rotor and surrounding reactor wall or through the use of devices along the length of dispersion reactor 20 such as perforated plates and baffles to prevent rapid bulk mixing in the axial direction.
  • Dispersion reactor 20 can also be broken into one or more sections comprising heating and dispersion sections and cooling sections, each operating under different shear conditions. That portion of the rotor operating within the heated portion of dispersion reactor 20 can be supplied with heated fluid, while that portion of the rotor operating within the cooled section of the reactor can be supplied with a cooling fluid.
  • Heat may be applied to dispersion reactor 20 by oil from hot oil heating unit 42 through oil pump 44. It should be noted that heat may be added to dispersion reactor 20 using heating bands or other suitable heat transfer fluids. Cooling can be accomplished using any conventional heat exchanger method, including the use of a cooling coil located on the surface or within the wall of dispersion reactor 20.
  • Dispersion reactor 20 may be fitted with an upright dead-ended section or stubber, (not shown), that is filled with a gas bubble.
  • This stubber serves to prevent pressure pulses and allows accurate control of reactor pressure by providing a volume of compressible fluid within the system.
  • the stubber includes a pressurization tank having one portion filled with reactor fluid and another section filled with gas. A thick rubber septum can be used to separate these two materials to provide a transmission of pressure forces.
  • the reactor is equipped with instrumentation suitable to measure temperature, pressure, and other critical parameters.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)

Abstract

L'invention concerne un procédé à étapes multiples destiné à la production de polymères finement divisés. Ledit procédé consiste à moudre mécaniquement le polymère en poudre, puis à disperser cette poudre moulue dans un mélange d'eau et d'un agent de surface à une température, une pression et un cisaillement élevés. On place le polymère en poudre dans un tel environnement, qu'il s'équilibre rapidement à la température élevée, fond et se disperse dans des séries plus fines de gouttelettes qui peuvent être refroidies pour former des particules très fines. On peut utiliser la dispersion résultante comme un latex ou on peut séparer les particules polymères solides à partir du fluide par le biais d'étapes de lavage et de séchage traditionnelles.
PCT/US2001/014732 2000-05-23 2001-05-08 Procede de production de polymeres finement divises Ceased WO2001090240A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57651900A 2000-05-23 2000-05-23
US09/576,519 2000-05-23

Publications (1)

Publication Number Publication Date
WO2001090240A1 true WO2001090240A1 (fr) 2001-11-29

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002062875A1 (fr) * 2001-02-06 2002-08-15 E.I. Dupont De Nemours And Company Micronisation de particules de polymere
WO2025198619A1 (fr) 2024-03-22 2025-09-25 Ecolab Usa Inc. Stratégies de traitement pour protéger contre le blocage et l'encrassement des corps polymères capables de s'écouler

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4123403A (en) * 1977-06-27 1978-10-31 The Dow Chemical Company Continuous process for preparing aqueous polymer microsuspensions
US4252696A (en) * 1979-03-12 1981-02-24 Koppers Company, Inc. High-speed pultrusion polyester resins and process

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4123403A (en) * 1977-06-27 1978-10-31 The Dow Chemical Company Continuous process for preparing aqueous polymer microsuspensions
US4252696A (en) * 1979-03-12 1981-02-24 Koppers Company, Inc. High-speed pultrusion polyester resins and process

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002062875A1 (fr) * 2001-02-06 2002-08-15 E.I. Dupont De Nemours And Company Micronisation de particules de polymere
WO2025198619A1 (fr) 2024-03-22 2025-09-25 Ecolab Usa Inc. Stratégies de traitement pour protéger contre le blocage et l'encrassement des corps polymères capables de s'écouler

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