USH1055H - Thermal energy coagulation and washing of latex particles - Google Patents

Thermal energy coagulation and washing of latex particles Download PDF

Info

Publication number
USH1055H
USH1055H US07/530,146 US53014690A USH1055H US H1055 H USH1055 H US H1055H US 53014690 A US53014690 A US 53014690A US H1055 H USH1055 H US H1055H
Authority
US
United States
Prior art keywords
latex
coagulation
polymer
thermal energy
washing
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.)
Abandoned
Application number
US07/530,146
Other languages
English (en)
Inventor
Nicholas Kydonieus
Jeffrey A. Hall
James D. Phillips, Jr.
John A. Sturm
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.)
Arkema Inc
Original Assignee
Atochem North America Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Atochem North America Inc filed Critical Atochem North America Inc
Priority to US07/530,146 priority Critical patent/USH1055H/en
Assigned to ATOCHEM NORTH AMERICA, INC., A CORP. OF PA reassignment ATOCHEM NORTH AMERICA, INC., A CORP. OF PA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HALL, JEFFREY A., PHILLIPS, JAMES D. JR., STURM, JOHN A., KYDONIEUS, NICHOLAS
Priority to DE69019342T priority patent/DE69019342T2/de
Priority to EP90122738A priority patent/EP0460284B1/de
Priority to JP2326108A priority patent/JPH07119253B2/ja
Assigned to ELF ATOCHEM NORTH AMERICA, INC. reassignment ELF ATOCHEM NORTH AMERICA, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE ON 12/31/1991 Assignors: ATOCHEM NORTH AMERICA INC.
Application granted granted Critical
Publication of USH1055H publication Critical patent/USH1055H/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F6/00—Post-polymerisation treatments
    • C08F6/14—Treatment of polymer emulsions
    • C08F6/22—Coagulation

Definitions

  • the invention relates to the coagulation and washing of hydrocarbon polymer particles, in particular the coagulation and washing of such particles formed by an emulsion polymerization process.
  • Latex coagulation has been performed in the past by subjecting the latex to severe mechanical sheer in specialized multistage coagulator equipment.
  • the object of the imparted sheer is to increase the kinetic energy of the individual latex particles to a level such that, upon interparticle impact, the repulsive force exerted by the particles' surfactant coating is overcome, causing particle agglomeration.
  • Particle agglomeration results in the formation of particle flocks consisting of hundreds or thousands of particles, depending on the nature of the polymer and the degree of coagulation.
  • a satisfactory degree of coagulation in this context may be viewed as the formation of aerated flocks of sufficiently large size, such that the flocks may ascend a wash column with sufficient velocity to avoid column flooding at a given velocity of countercurrent wash water.
  • Particle flocks may be washed in countercurrent wash columns to remove water soluble impurities, such as is disclosed in U.S. Pat. No. 4,128,517, for example.
  • the degree of coagulation achieved depends primarily on the amount of mechanical shear energy imparted to the polymer, per unit mass of polymer. The degree of coagulation further depends upon the nature of the polymer. For one class of polymers, the polyvinylidene fluoride homopolymers and copolymers, the energy input generally required for coagulation varies from about 0.05 to about 0.5 horsepower-hour per pound of polymer. The specific coagulation energy requirement of a given polymer resin appears to depend primarily on the polarity of the polymer, which interacts with surfactant which may remain in the latex from the emulsion polymerization process.
  • a method for coagulating and washing an aqueous polymer latex for removing water-soluble contaminants is provided.
  • the latex is imparted with a combination of mechanical and thermal energy sufficient to result in coagulation.
  • the coagulated latex is thereafter washed by passing it in counter-current relationship with wash water.
  • the method is particularly useful for coagulating and washing fluorocarbon polymer latices, most particularly, latices of vinylidene fluoridebased polymers.
  • thermal energy is applied to polymer latex particles by heating the latex to a temperature no higher than about 20° C. below the melting temperature of the polymer.
  • mechanical energy is meant any form of energy, other than thermal energy, which when applied to latex particles, results in an increase in the particles' velocity.
  • thermo energy energy applied in the form of heat.
  • fluorocarbon polymer any of the organic polymers analogous to hydrocarbon polymers in which one or more hydrogen atoms on the monomer unit have been replaced by fluorine.
  • fluorocarbon polymers that is, polymers consisting only of carbon, fluorine and hydrogen atoms, but also to include polymers that contain other atoms, e.g. chlorine, in addition to carbon and fluorine.
  • fluorocarbon polymer includes, for example, polytetrafluoroethylene, polymers of chlorotrifluoroethylene, fluorinated ethylene-propylene polymers, polyvinylidene fluoride, polymers of hexafluoropropylene, and the like.
  • vinylidene fluoride-based polymer as used herein is meant to include not only homopolymers of vinylidene fluoride, but also copolymers, including terpolymers, of vinylidene fluoride and monomers copolymerizable therewith, such as tetrafluoroethylene, hexafluoropropylene, vinyl fluoride, trifluoroethylene, and the like.
  • Typical examples of such copolymers are vinylidene/tetrafluoroethylene copolymer and vinylidene/tetrafluoroethylene/hexafluoropropylene terpolymer.
  • the FIGURE is a flow diagram of a polymer latex finishing system for the practice of the invention.
  • the present method for latex coagulation and washing may be utilized in any situation where the formation of particle flocks from latex particles is desired.
  • the invention is particularly useful in the coagulation of polymer latices prior to washing in counter-current relationship with wash water to remove water-soluble contaminants from the latex.
  • the wash water is preferably pure deionized water, although the incorporation of cleaning or washing aids to the water may be practiced.
  • wash column performance In addition to energy savings in the coagulation process, the practice of the invention results in an improvement in wash column performance. Washing of the particle flocks formed by latex coagulation may be accomplished by passing the preferably aerated flocks countercurrently through deionized water in a multistage countercurrent agitated conductor.
  • the construction of such devices is known to those skilled in the art.
  • the upward progress of the flocks through the wash column may be halted, resulting in column flooding and polymer loss in the spent wash water stream.
  • the particle flock size is very large, and the flock density is quite low. The column capacity and washing efficiency are effectively increased. As a result, the wash column may be operated at higher wash column velocities, permitting greater latitude in washing operations and essentially complete removal of water-soluble contaminants.
  • the increase in washing efficiency permits the production of ultrapure grades of polymer resin. Loss of polymer in the wash process, apparent as the formation of a haze in the wash water, is minimized or virtually eliminated. The haze is caused, to a large extent, by the incomplete flocculation of the latex particles in the coagulation process.
  • latex particles generated, for example, from an emulsion polymerization process are collected for processing as an aqueous suspension.
  • polymer suspensions formed by emulsion polymerization which may be coagulated according to the present invention include, for example, polymers and copolymers of vinyl chloride, vinyl fluoride, vinyl acetate, styrene, alkyl acrylates, alkyl methacrylates, acrylonitrile, vinylidene chloride, vinylidene fluoride, ethylene, propylene, tetrafluoroethylene, isoprene, chloropropene, butadiene and the like.
  • the invention is particularly useful in the coagulation of fluorocarbon polymer particles, and most particularly in the coagulation of vinylidene fluoride-based polymer particles.
  • vinylidene fluoride-based polymers are prepared by polymerizing vinylidene fluoride monomers with or without copolymerizable comonomers in an aqueous medium containing a water-soluble surfactant, an organic peroxide initiator suitable for vinylidene fluoride polymerization, and optionally wax to stabilize the emulsion.
  • Typical water-soluble fluorosurfactants for this purpose are taught, for instance, in U.S. Pat. Nos. 2,559,752, 2,239,970 or 4,360,652.
  • the emulsion particles are generally still coated with the surfactant from the emulsion polymerization process.
  • the surfactant coating is responsible for a particle-particle repulsion which may be overcome by increasing the kinetic energy content of the particles. Increasing the kinetic energy results in an increased number and velocity of particle collisions. When the collisions become sufficiently energetic to overcome the interparticle repulsive force, flocculation occurs.
  • the kinetic energy of the particles is increased according to the present invention by imparting a combination of mechanical and thermal energy to the particles.
  • the total energy applied may comprise up to about 85% thermal energy, preferably up to about 75%, the balance comprising mechanical energy.
  • at least about 50% of the applied energy should comprise thermal energy.
  • the mechanical energy imparted to the particles may derive, for example, from a mechanical shear caused by a mechanical agitator, e.g., rotor, or by a hydraulic shear achieved by forcing the latex through a small orifice under pressure. Coagulation devices for generating such sheer forces are known to those skilled in the art.
  • the thermal energy may be imparted to the latex particles by any means which results in an increase in the heat content of the particles, i.e., by radiation, conduction, and/or convection.
  • the thermal energy is most effectively imparted to the particles by treating the latex particles with steam or hot water as they enter the coagulation device.
  • the steam or hot water treatment is conducted to an extent which will result in up to about 85% of the total energy increase imparted to the particles in the coagulator device being derived from the applied thermal energy.
  • the actual level of thermal energy imparted to the particles, reflected in a temperature increase in the coagulation device above the temperature achieved without thermal energy input, will depend upon the nature of the polymer comprising the latex particle and the particular construction of the coagulator.
  • the coagulation of the latex may be achieved with aeration as described in U.S. Pat. No. 4,128,517. Aeration before washing produces a foam wherein the suspended polymer particles have a reduced apparent density. The foamed product is then washed by passing it in countercurrent relationship with wash water.
  • the coagulator and washing components of a typical polymer finishing system is described in the FIGURE.
  • the coagulation method of the invention may be advantageously utilized in conjunction with any counter-current polymer latex wash system, and particularly the wash system described in U.S. Pat. No. 4,128,517, the entire disclosure of which is incorporated herein by reference.
  • the coagulated latex is passed in counter-current relationship upward through a column fed with wash water at the top.
  • the washed product is continuously recovered.
  • polymer latex is contained in feed tank 1.
  • wash water Prior to introduction of the latex into coagulator 3, wash water is allowed to enter wash column 5 through flow meter 7 by manipulating valve 10.
  • Vent valve 9 is opened and column 5 allowed to fill with water; then the vent valve is closed.
  • the column pressure will increase until back pressure valve 6 setting is reached, thereafter back pressure valve 6 will maintain column pressure by discharging sufficient water.
  • latex pump 2 is started in order to introduce latex into the coagulator 3 at a predetermined rate, with a controlled amount of steam or hot water being fed through valve 15.
  • the latex flow rate can be controlled with the pump speed.
  • valve 12 is opened sufficiently to allow air to enter coagulator 3 at a predetermined rate regulated by flowmeter 4.
  • the coagulator agitator is then started to coagulate and aerate the latex.
  • the coagulated and aerated latex fills the coagulator 3 displacing the excess air from the coagulator 3 into the column 5.
  • the excess air in column 5 is vented through vent valve 9.
  • the column agitator is started.
  • the coagulated latex froth ascends in column 5 coming into contact with wash water in a countercurrent fashion to rid the polymer particles of water soluble contaminants.
  • the washed polymer reaches the top of column 5, where it forms a cake.
  • the air feed to coagulator 3 and water feed to wash column 5 are monitored by meters 4 and 10, respectively. Wash column pressure is monitored by indicator 11.
  • the cake is piped to thickener 14, which functions as an inverse sedimentation tank, i.e., the polymer flock, due to its lower density, settles to the top of the tank, and the excess water is cycled to the wash column.
  • a top rake 16 revolves at a low speed, e.g., 1 rpm, to eliminate cake "ratholing". Vertical fingers on the rake facilitate water drainage, increasing the latex concentration.
  • discharge pump 8 When the washed polymer cake reaches a desired size, discharge pump 8 is started at such a rate as to maintain the polymer cake size.
  • the product of the system discharging through pump 8 may be sent to a dryer, and then to a packaging system.
  • the column wash water is warmed to at least about 50° C., preferably from about 70° C. to about 80° C. we have found unexpectedly that a warm wash water contributes to the efficiency of the washing process, as evidenced by the clarity of the spent wash water. If the wash water is not heated, a slight haze may be apparent in the spent water.
  • Sufficient steam or hot water should be combined with the latex entering the coagulator through valve 15 such that the mechanical energy input to the latex required for successful coagulation (achieved by the mechanical shear exerted by the coagulator) may be reduced without sacrificing coagulator efficiency.
  • the amount of thermal energy imparted to the polymer latex, reflected in the increase in the latex temperature, depends primarily on the nature of the polymer. The appropriate amount of thermal energy can be readily ascertained by those skilled in the art from the present disclosure and routine experimentation.
  • the temperature of the latex in the coagulator preferably should not generally exceed a temperature which is about 20° C. below the polymer melting point, as determined by differential scanning calorimetry.
  • the temperature of the coagulated latex at the coagulator output is thus advantageously continuously monitored by a coagulation temperature controller (not shown) which communicates with the hot water-/steam source supplying hot water or steam through valve 15.
  • the temperature of the coagulator is controlled by manipulating the supply of steam or hot water.
  • the wash column and thickener as described above were filled with deionized water.
  • Vinylidene fluoride homopolymer was discharged from an aqueous reaction system as a 30% solids latex diluted with water to 15-20% solids (0.25-0.32 micron particle size), and piped to a coagulator substantially as described above.
  • the latex contained other reaction ingredients, such as surfactant, buffer, catalyst fragments, and the like.
  • the water-soluble contaminants are removed in the washing system.
  • the coagulator generally as shown in the FIGURE at 3, was equipped with high shear agitators capable of imparting shear energy to the process latex at a minimum rate of 0.05 horsepower per pound (hp/lb) of solids.
  • the chambers of the coagulator were baffled to increase the power coupling between the agitators and the aerated latex.
  • the coagulator had a length of approximately two feet and a diameter of about 12 inches, and was equipped with four agitation stages.
  • the latex was fed through the coagulator at a rate of 25 pounds solids/hour.
  • the latex was coagulated and aerated by agitation utilizing an agitation speed adjusted to afford the minimum specific mechanical energy input required for coagulation of the vinylidene fluoride homopolymer: 0.48 hp-hr/lb.
  • the resulting coagulated, aerated latex was then fed to a fourteen-stage, 9-inch inside diameter counter-current wash column generally shown as 5 in the FIGURE.
  • the latex was washed in counter-current fashion with deionized water to remove water-soluble contaminants.
  • the flock rose to the top of the column and was transferred to a thickener of the type described above, designated as 14 in the FIGURE.
  • the polymer flock was concentrated in the thickener and fed to a spray dryer.
  • the spent wash water displayed a hazy appearance, indicating some polymer losses in the wash column, due to coagulation inefficiency in the coagulation stage.
  • Comparative Example 1 The procedure of Comparative Example 1 was repeated except that steam was injected into the latex feed stream to the coagulator via valve 15 at the rate of 6 lb/hr, such that the discharge temperature of the coagulator was controlled at 175° F. (79.4° C.). Particle flocks having a density of between 0.2 and 0.6 g/cm 3 were obtained. The haze of the spent wash water from the wash column became clear within 15 minutes of operation. The agitator speed in the coagulator was then slowed so that the specific mechanical energy input was reduced from 0.48 to 0.14 hp-hr/lb. The steam injection rate increased to 4 lbs/hr, while the coagulator temperature controller maintained the coagulation temperature at 175° F. (79.4° C.), by manipulating the steam injection rate. The spent wash water maintained a clear appearance through this adjustment.
  • the feed rate of the material through the coagulator/wash system was increased gradually from the 25 lb/hr rate of Example 1 to determine the point at which the degree of latex coagulation was decreased sufficiently to result in hazing of the wash column spent water.
  • the results are set forth in the Table.
  • the feed rate was increased to the maximum capacity of the system feed pump of 48 lb/hr without hazing of the spent water at a steam feed rate of 27 lb/hr, which maintained the coagulator temperature at 175° F. (79.4° C.). See Example 9.
  • the system was allowed to run at 48 lb/hr latex feed rate and 27 lb/hr steam injection rate for two hours, without hazing of the spent wash water.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
US07/530,146 1990-05-29 1990-05-29 Thermal energy coagulation and washing of latex particles Abandoned USH1055H (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US07/530,146 USH1055H (en) 1990-05-29 1990-05-29 Thermal energy coagulation and washing of latex particles
DE69019342T DE69019342T2 (de) 1990-05-29 1990-11-28 Koagulation mit thermischer Energie und Waschung der Latexteilchen.
EP90122738A EP0460284B1 (de) 1990-05-29 1990-11-28 Koagulation mit thermischer Energie und Waschung der Latexteilchen
JP2326108A JPH07119253B2 (ja) 1990-05-29 1990-11-29 ラテックス粒子の熱エネルギー凝固及び洗浄

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US07/530,146 USH1055H (en) 1990-05-29 1990-05-29 Thermal energy coagulation and washing of latex particles

Publications (1)

Publication Number Publication Date
USH1055H true USH1055H (en) 1992-05-05

Family

ID=24112610

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/530,146 Abandoned USH1055H (en) 1990-05-29 1990-05-29 Thermal energy coagulation and washing of latex particles

Country Status (4)

Country Link
US (1) USH1055H (de)
EP (1) EP0460284B1 (de)
JP (1) JPH07119253B2 (de)
DE (1) DE69019342T2 (de)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6720360B1 (en) 2000-02-01 2004-04-13 3M Innovative Properties Company Ultra-clean fluoropolymers
US6593416B2 (en) 2000-02-01 2003-07-15 3M Innovative Properties Company Fluoropolymers
JP5055652B2 (ja) 2000-08-11 2012-10-24 ダイキン工業株式会社 含フッ素界面活性剤の回収方法
CN1332988C (zh) 2001-09-26 2007-08-22 霓佳斯株式会社 氟橡胶模塑产品及其生产方法
US6991732B2 (en) 2003-07-02 2006-01-31 Arkema Process for the recovery of fluorosurfactants by active charcoal
JP4125268B2 (ja) 2004-07-07 2008-07-30 株式会社島精機製作所 横編機における給糸装置のヤーンフィーダ
ITMI20050705A1 (it) * 2005-04-20 2006-10-21 Solvay Solexis Spa Processo per la preparazione di dispersori di fluoropolimeri
JP2011012142A (ja) * 2009-06-30 2011-01-20 Nippon Zeon Co Ltd ゴムを連続的に製造する方法
FR3043084B1 (fr) 2015-10-29 2017-10-27 Arkema France Copolymeres fluores fonctionnalises
FR3069544B1 (fr) 2017-07-28 2020-05-15 Arkema France Procede de preparation d'un film de polymere fluore reticule
CN110016098B (zh) * 2019-02-25 2021-03-26 聊城氟尔新材料科技有限公司 一种聚全氟乙丙烯生产凝聚洗涤装置

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR958106A (de) * 1946-05-18 1950-03-03
DE954920C (de) * 1955-02-19 1956-12-27 Hoechst Ag Verfahren zum Aufarbeiten von Emulsionen von Polyvinylverbindungen, insbesondere Polyvinylchlorid
US4128517A (en) * 1977-11-01 1978-12-05 Pennwalt Corporation Method of washing polymer latices by aerating
US4299952A (en) * 1980-03-24 1981-11-10 The Dow Chemical Company Method for recovering synthetic resinous latex solids
JPS5880303A (ja) * 1981-11-10 1983-05-14 ザ・ダウ・ケミカル・カンパニ− 合成樹脂質ラテツクス固体の回収法

Also Published As

Publication number Publication date
JPH0433902A (ja) 1992-02-05
JPH07119253B2 (ja) 1995-12-20
EP0460284A2 (de) 1991-12-11
EP0460284B1 (de) 1995-05-10
EP0460284A3 (en) 1992-04-29
DE69019342T2 (de) 1995-10-19
DE69019342D1 (de) 1995-06-14

Similar Documents

Publication Publication Date Title
USH1055H (en) Thermal energy coagulation and washing of latex particles
Vanderhoff Mechanism of emulsion polymerization
DE1002128B (de) Verfahren zur kontinuierlichen Polymerisation von Acrylnitril, gewuenschtenfalls zusammen mit anderen mischpolymerisierbaren Monoolefinen
CA1049175A (en) Styrene-butadiene copolymer latices containing carboxyl groups
DK150904B (da) Fremgangsmaade til fremstilling af latexer ved emulsionspolymerisationaf vinylchlorid
JP3145665B2 (ja) 微粒子の含有率が高い２つの粒径分布を有する塩化ビニルをベースにしたポリマーのラテックスと、このラテックスの製造方法と、その利用
CA1118120A (en) Process for continuous coagulation and washing of polymer latices
Vanderhoff Recent advances in the preparation of latexes
CS200188B2 (en) Method of removing volatile compounds from water-dispersions of plastics,polymers part of which contains at least 50 percent by weight of polymerized vinyl chloride,by the continuous action with gases and device for making the method
US3719572A (en) Aqueous latices of high polymer compositions and processes and means for the production thereof
US2847405A (en) Continuous process for the polymerization of acrylonitrile
JPH1095806A (ja) 平均粒径が異なる２つの粒子群を含む塩化ビニル共重合体のラテックスと、その製造方法と、その利用
NO146639B (no) Fremgangsmaate for fjerning av vinylklorid fra polyvinylkloridholdige latekser
Zerfa et al. Experimental investigation of vinyl chloride drop behavior during suspension polymerization
JPH05155908A (ja) 複数の形態の塩化ビニルポリマーのラテックスの製造方法
EP1277765B1 (de) Verfahren zur Herstellung von hautfreiem PVC
US4948872A (en) Process for spray drying of vinyl chloride homopolymers and copolymers
KR930003103B1 (ko) 파종된 미소현탁액 내에서 비닐클로라이드 단일 - 및 공중합체의 제조방법
US4833180A (en) Process for polymerizing vinyl chloride in emulsion or in microsuspension
GB961551A (en) Method of improving the colloidal properties of a high solids synthetic rubber latex
US3830883A (en) Polymerisation process
CA1144295A (en) Homogenizer process for forming emulsion/suspension polymers
CA1152695A (en) Method of polymerizing vinyl chloride
US4128516A (en) Process for the gentle degasification of coagulation-sensitive PVC latices
US20030032724A1 (en) Process for producing graft copolymer latex

Legal Events

Date Code Title Description
AS Assignment

Owner name: ATOCHEM NORTH AMERICA, INC., A CORP. OF PA, PENNS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KYDONIEUS, NICHOLAS;HALL, JEFFREY A.;PHILLIPS, JAMES D. JR.;AND OTHERS;REEL/FRAME:005521/0021;SIGNING DATES FROM 19900625 TO 19900702

AS Assignment

Owner name: ELF ATOCHEM NORTH AMERICA, INC., PENNSYLVANIA

Free format text: CHANGE OF NAME;ASSIGNOR:ATOCHEM NORTH AMERICA INC.;REEL/FRAME:006094/0524

Effective date: 19911230

STCF Information on status: patent grant

Free format text: PATENTED CASE