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CA-3044128-C - METHOD OF PRODUCING UNIFORM POLYMER BEADS BY VIBRATION JETTING WITH SUPERHYDROPHOBIC MEMBRANE

CA3044128CCA 3044128 CCA3044128 CCA 3044128CCA-3044128-C

Abstract

Speriodal polymer beads having a uniform size are prepared by polymerizing uniformly sized 5 monomer droplets formed by dispersing a polymerizable monomer phase over double-walled cylindrical cross-flow membrane into an suspension phase. A shear force is provided at a point of egression of the polymerizable monomer phase into the suspension phase, the direction of shear substantially perpendicular to the direction of egression of the monomer phase. The membrane is metallic and includes a superhydrophobic coating.

Inventors

  • Serguei Rudolfovich Kosvintsev

Assignees

  • Purolite (China) Co., Ltd.

Dates

Publication Date
20260505
Application Date
20171215
Priority Date
20170222

Claims (20)

  1. WHAT IS CLAIMED IS: 1. A method for preparing spheroidal polymer beads having a volume average particle diameter of about 10 to about 180 μm, the method comprising the steps of: providing a double-walled cylindrically shaped apparatus comprising a metallic membrane containing a plurality of through holes, wherein the metallic membrane is nickel and is coated with 5 a superhydrophobic coating, wherein a first volume is in contact with a first side of the membrane and a second volume is in contact with a second side of the membrane, the first volume comprising a water-soluble polymerizable monomer phase, the second volume comprising a liquid immiscible with the monomer phase; dispersing the first volume through the through holes into the second volume under 10 conditions sufficient to form a plurality of monomer droplets comprising the polymerizable monomer, wherein a shear force is provided at a point of egression of the first volume into the second volume, the direction of shear substantially perpendicular to the direction of egression of the first volume, and the shear force is provided by displacing the membrane relative to the second volume; and 15 polymerizing the droplets dispersed in the second volume.
  2. 2. The method according to claim 1, wherein the membrane comprises from about 200 to about 2,000 through holes per cm2 of the membrane.
  3. 3. The method according to claim 1, wherein the through holes have a diameter in the range of about 1 μm to about 100 μm. 20
  4. 4. The method according to claim 3, wherein the through holes have a diameter in the range of about 20 μm to about 60 μm. CA 3044128 26
  5. 5. The method according to claim 1, wherein the plurality of through holes are positioned from each other at a distance of at least about 20 times the diameter of each through hole when the distance is measured from the center of each through hole.
  6. 6. The method according to claim 1, wherein the monomer phase is dispersed through the through holes into the second volume at a rate of about 1 to about 50 cm/s. 5
  7. 7. The method according to claim 1, wherein the beads have a particle size distribution having a uniformity coefficient of less than 1.2.
  8. 8. The method according to claim 1, wherein the displacing is rotating, pulsing, or oscillating movement.
  9. 9. The method according to claim 1, wherein the first volume is dispersed into the second 10 volume by applying pressure to the first volume.
  10. 10. The method according to claim 1, wherein the membrane is nickel-plated.
  11. 11. The method according to claim 1, wherein the plurality of through holes are conical shaped.
  12. 12. The method according to claim 1, wherein the through holes are in the shape of a slot, with an aspect ratio of slot width to slot length of at least 1:2. 15
  13. 13. The method according to claim 1, wherein the dispersed phase comprises agarose or other gel forming compounds.
  14. 14. The method according to claim 1, wherein the polymerizable monomer phase comprises a porogen. CA 3044128 27
  15. 15. The method of claim 1, wherein the superhydrophobic coating is polytetrafluoroethylene.
  16. 16. The method of claim 15 wherein the polytetrafluoroethylene coating comprises particles of polytetrafluoroethylene.
  17. 17. The method of claim 15 wherein the polytetrafluoroethylene coating further comprises nanoparticles of elemental nickel. 5
  18. 18. The method of claim 15, wherein the superhydrophobic coating is applied to said membrane by electroless deposition.
  19. 19. The method of claim 15, further comprising a coating of amorphous polytetrafluoroethylene applied to the upper surface of the polytetrafluoroethylene coating.
  20. 20. A method for preparing spheroidal agarose beads having a volume average particle 10 diameter of about 10 to about 180 μm, the method comprising the steps of: providing a double-walled cylindrically shaped apparatus comprising a metallic membrane containing a plurality of through holes, wherein the metallic membrane is nickel and is coated with a superhydrophobic coating, wherein a first volume is in contact with a first side of the membrane and a second volume is in contact with a second side of the membrane, the first volume comprising agarose solution in 15 water, the second volume comprising a liquid immiscible with the agarose solution; dispersing the agarose solution through the through holes into the liquid immiscible with the agarose solution under conditions sufficient to form a plurality of agarose droplets, wherein a shear force is provided at a point of egression of the first volume into the second volume, the direction of shear substantially perpendicular to the direction of egression of the first volume, and the shear force is 20 28 provided by displacing the membrane relative to the second volume; and hardening the agarose droplets dispersed in the second volume to form agarose beads.

Description

METHOD OF PRODUCING UNIFORM POLYMER BEADS BY VIBRATION JETTING WITH SUPERHYDROPHOBIC MEMBRANE 10 FIELD OF THE INVENTION [0001] The present invention relates generally to the preparation of spheroidal polymer beads, and more particularly, to the preparation of spheroidal polymer beads having a substantially uniform particle size by vibration jetting with a superhydrophobic membrane. BACKGROUND OF THE INVENTION [0002] Spheroidal polymer beads in the size range from about 1 to 300 μmin diameter 20 are useful for a variety of applications. For example, such polymer beads have been employed for various chromatographic applications, as substrates for ion exchange resins, seeds for the preparation of larger sized polymer particles, calibration standards for blood cell counters, aerosol instruments, in pollution control equipment, and as spacers for photographic emulsions, among other uses. 25 [0003] Unfortunately, however, the preparation of uniformly sized polymer beads using known methods is often not suitable for large-scale production. Typically, polymer beads can be prepared by suspension polymerization by dispersing an organic monomer phase as droplets in a vessel equipped with an agitator and an aqueous phase in which the monomer and resulting polymer are essentially insoluble. The dispersed monomer droplets are subsequently 30 polymerized under continuous agitation (see, for example, U.S. Pat. Nos. 3,728,318; 2,694,700; and 3,862,924). Polymer beads are also manufactured by ''jetting" liquid organic monomer 1 mixtures through capillary openings into an aqueous phase or gaseous phase. The monomer droplets are then transported to a reactor where polymerization occurs, as described, for example, 5 in U.S. Pat. Nos. 4,444,961; 4,666,673; 4,623,706; and 8,033,412. However, these conventional methods, such as stirred batch polymerization, often produce bead products exhibiting large particle size distributions, primarily due to problems of non-controllable coalescence and/or breakage of the suspended monomer droplets. Existing jetting methods also suffer from high cost and low output for particle size products of less than 300 μm. For example, plate jetting 10 methods have low overall productivity and are limited by large energy losses during the vibration generation step. Moreover, methods which require jetting into a gaseous media demand very sophisticated equipment and complex methods for polymer formation. The use of cross-flow membranes for the generation of fine droplets using a metal or glass sintered or electro-formed membrane is appropriate for small scale applications but is unfeasible for commercial operation. 15 Further, the low productivity per unit area of the cross flow membrane requires complex and bulky equipment which is unreliable and demands high capital and operating costs. Metallic plate or can-shaped membranes, preferably of nickel or nickel-plated are desirable for use in vibration jetting. However, while such plates are relatively long-lived, over time they are known to experience wear during use. Such wear alters the configuration and geometry of the membrane 20 pores ( or "through holes"; as used herein the terms pores and through holes are interchangeable), and increases non-uniform drag on the monomer, resulting in inconsistent, nonuniform bead production and increased energy costs. Therefore, an object of the present invention is to provide a metallic membrane with a durable surface, providing a long service life without deterioration. Other jetting method for producing polymer beads are described in U.S. Patents 25 9,028,730 and 9,415,530. 2 SUMMARY OF THE INVENTION [0004] An object of the invention is to provide a method for preparing uniform sized spheroidal polymer beads having a uniform particle size and narrow particle size distribution, using vibration jetting with a superhydrophobic membrane. In particular, the polymer beads are made from water soluble (hydrophilic) substances such as agarose and other gelating natural hydrocolloids such as chitin, pectin, gelatin, gellan, cellulose, alginate, carrageenan, starch, 10 xanthan gum, among others. In addition, gelating synthetic polymers such as PV A, (polyvinyl acetate), PVP (polyvinyl pyrrolidone) and PEG (polyethylene glycol) may be employed. Further, polymerizable water soluble monomers such as acrylic among others may be used. As used herein, each of these starting materials are referred to interchangeably as forming "polymers" or "hydrocolloids". Of these starting materials, agarose is preferred. Agarose beads are useful as 15 providing a base for example in chromatography media. Agarose is resistant to acid, base and solvents, is hydrophilic, has high porosity and a large number of hydroxyl groups for functionalization. See U.S. Patent 7,678,302. [0005] Accordingly, one embodiment of the invention is directed to a method for preparing uniform spheroidal polymer beads having a volume mean particle diameter (Dso) of 20 abou