Process and apparatus for preparing uniform size polymer beads

• US 4,444,961 A
• Filed: 07/14/1982
• Issued: 04/24/1984
• Est. Priority Date: 10/30/1980
• Status: Expired due to Term

• Current Assignee: Diamond Technology Partnership Company
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Timm, Edward E.
• Primary Examiner(s): Michl, Paul R.
• Application Number:
  US06/398,007
• Time in Patent Office: 650 Days
• Field of Search: 526/88, 521/29, 521/31, 521/33
• US Class Current: 526/88
• CPC Class Codes: B01J 14/00 Chemical processes in general for reacting liquids with liquids; Apparatus specially adapted therefor B01J8/00, B01J19/08 take precedence
• CPC Class Codes: B01J 19/18 Stationary reactors having moving elements inside B01J19/08, B01J19/26 take precedence
• CPC Class Codes: B01J 19/241 of the pulsating type
• CPC Class Codes: B01J 2219/0004 Processes in series
• CPC Class Codes: B01J 4/004 Sparger-type elements
• CPC Class Codes: B29B 9/10 by moulding the material, i.e. treating it in the molten state
• CPC Class Codes: C08F 2/20 with the aid of macromolecular dispersing agents
• CPC Class Codes: C08F 2/32 Polymerisation in water-in-oil emulsions

Abstract

Spheroidal polymer beads having a uniform size are prepared by polymerizing uniformly sized monomer droplets formed by the vibratory excitation of a laminar jet of monomeric material flowing in a continuous liquid medium containing a suitable suspending agent. For example, a laminar jet of a monomer mixture comprising a monovinylidene aromatic such as styrene, a polyvinylidene aromatic such as divinylbenzene and a polymerization initiator can be subjected to vibratory excitation and the resulting monomer droplets polymerized to yield copolymer beads having a narrow particle size range distribution. The resulting copolymer beads can be employed to prepare high yields of ion exchange resins exhibiting superior properties, particularly in continuous ion exchange operations.

Claims

1. A method for preparing spheroidal polymer beads, said method comprising the steps of forming a monomer jet of a monomer phase comprising a polymerizable monomer having laminar flow characteristics by flowing the monomer phase through an opening into a continuous phase comprising a liquid immiscible with the polymerizable monomer or monomer phase and a stabilizing amount of a suspending agent;

vibratorily exciting the jet to form a plurality of monomer droplets suspended in said continuous phase, transfering said suspended monomer droplets into a polymerization reaction vessel without significant coalescence or additional dispersion thereof, and substantially without the polymerization thereof, and subsequently polymerizing the monomer in suspension at conditions which do not cause significant coalescence or additional dispersion thereof.

2. The method of claim 1 wherein the monomer droplets have a particle size distribution such that the coefficient of variance of their particle size is less than about 0.1.

3. The method of claim 1 wherein the flow characteristics of the monomer jet is defined by a Reynolds number from about 1 to about 2,000 and the vibratory excitation of the monomer jet is defined by a Strouhal number from about 0.05 to about 5.

4. The method of claim 1 wherein the monomer droplets possess a different density than the continuous phase and the monomer droplets move through the continuous phase, substantially in the direction imparted to the monomer droplets by the difference in density between the monomer droplets and the continuous phase into a polymerization reaction vessel, said continuous phase being stationary or being flowed in the direction of the flow of the monomer droplets in a cocurrent flow operation.

5. The method of claim 4 wherein the flow rates of the continuous phase and the monomer jets are chosen such that the suspension of monomer droplets in the polymerization reaction vessel comprises from about 30 to about 60 volume percent of monomer droplets.

6. The method of claim 1 wherein the polymerization reaction vessel is agitated using an anchor, gate or loop-type agitator.

7. The method of claim 4 wherein the flow of the monomer jet is described by a Reynolds number from about 1 to about 1,200 and the vibratory excitation of the monomer jet is defined by a Strouhal number from about 0.15 to about 1.5, wherein said flow characteristics and conditions of vibratory excitement are such that the monomer droplets exhibit a particle size distribution with a coefficient of variance of less than about 0.05.

8. The method of claim 7 wherein the size of the monomer droplets is from about 0.15 to about 1.5 mm.

9. The method of claim 3 wherein the monomer jet is formed by flowing the monomer through a passage in a jet forming means, said passage having an opening with a diameter from about 0.06 to about 0.6 mm.

10. The method of claim 9 wherein a plurality of monomer jets is formed by flowing the monomer through an orifice plate having a plurality of generally cylindrical or frusto-conical passages, each passage having a cross-section with a diameter from about 0.08 to about 0.4 mm.

11. The method of claim 7 wherein the viscosity of the continuous phase is less than 50 cps at room temperature and from about 0.1 to about 10 times the viscosity of the monomer phase.

12. The method of claim 7 wherein the polymerizable monomer is a suspension polymerizable, water-insoluble monomer.

13. The method of claim 12 wherein the water-insoluble monomer is a monovinylidene aromatic, a polyvinylidene aromatic, a halo-olefin, an ester of an α

,β

-ethylenically unsaturated carboxylic acid or a mixture of two or more of said monomers.

14. The method of claim 13 wherein the monovinylidene aromatic is styrene or an alkyl substituted styrene and the polyvinylidene aromatic is divinylbenzene.

15. The method of claim 14 wherein the spheroidal polymer beads are subsequently converted to an ion exchange resin.

16. The method of claim 15 wherein the spheroidal polymer beads are sulfonated to form a strong acid cation exchange resin.

17. The method of claim 15 wherein the spheroidal polymer beads are halomethylated and subsequently aminated with ammonia or a primary or secondary amine to form a weak base anion exchange resin.

18. The method of claim 15 wherein the spheroidal polymer beads are halomethylated and subsequently aminated with a tertiary amine to form a strong base anion exchange resin.

19. The method of claim 13 wherein the monomer phase further comprises a free-radical, polymerization initiator and the continuous phase comprises an aqueous liquid containing a stabilizing amount of a suspending agent.

20. The method of claim 19 wherein said suspending agent is a water-soluble polymeric suspending agent which forms a film around the monomer droplets, which film exhibits an interfacial tension of at least 3 dynes/cm².

21. The method of claim 20 wherein the monomer droplets have a volume average diameter greater than about 400 microns and the water-soluble polymeric suspending agent forms a film around said droplets having an interfacial tension of at least 8 dynes/cm².

22. The method of claim 20 wherein the suspending agent is polyvinyl alcohol.

23. The method of claim 21 wherein the suspending agent is carboxymethylmethylcellulose.

24. The method of claim 13 wherein the monomer phase further comprises a pore-forming material comprising an inert organic liquid in which the monomer is soluble but the resulting polymer is insoluble.

25. The method of claim 7 wherein the polymerizable monomer is a water-soluble monomer and the monomer phase contains sufficient amounts of water to solubilize the polymer.

26. The method of claim 25 wherein the monomer is an ethylenically unsaturated carboxamide;

an aminoalkyl ester of a carboxylic acid or anhydride or an ethylenically unsaturated carboxylic acid.

27. The method of claim 26 wherein the monomer phase further comprises a free-radical, polymerization initiator and the continuous phase comprises an aromatic or aliphatic hydrocarbon or a halogenated hydrocarbon containing a stabilizing amount of a suspending agent.

28. The method of claim 7 wherein a polymerizable monomer is imbibed within the spheroidal polymer beads and the imbibed monomer subsequently polymerized.

34. The method of claim 1 wherein the polymerization reaction vessel is agitated.

29. An apparatus for preparing spheroidal polymer beads which comprises (1) a monomer reservoir containing a monomer phase comprising a polymerizable monomer, (2) a column containing a continuous phase of a suspending liquid immiscible with the polymerizable monomer or monomer phase and a stabilizing amount of a suspending agent, (3) a jet forming means in intimate contact with the monomer phase comprising the polymerizable monomer and the continuous liquid phase and having a passage connecting the monomer reservoir with the column containing the continuous phase such that the monomer phase is capable of flowing as a jet having laminar flow characteristics therethrough into the continuous phase, (4) a vibratory exciter capable of exciting the monomer jet such that the jet is broken into droplets and (5) a means for polymerizing the monomer in suspension at conditions such that significant coalescence or additional dispersion of the droplets does not occur.

30. The apparatus of claim 29 which further includes a means for introducing the suspending liquid into the column containing the continuous phase in close proximity to the jet forming means such that the monomer droplets and continuous phase flow through the column in an essentially cocurrent manner.

31. The apparatus of claim 30 wherein the jet forming means is an orifice plate having a plurality of generally cylindrical or frusto-conical passages, each passage having a cross-section of a diameter from about 0.08 to about 0.4 mm.

32. The apparatus of claim 31 wherein each passage of the orifice plate is spaced sufficiently apart such that the formation mechanism of the droplets is not significantly and deleteriously affected by an adjacent laminar flow jet and droplet formation therefrom.

33. The apparatus of claim 32 wherein each passage has a length less than about 10 times the diameter and wherein each passage is spaced at least about 1 mm and about 20 times the passage diameter from the passage nearest thereto when said distance is measured from the center of each passage.