Monofilament-reinforced hollow fiber membrane

• US 8,827,085 B2
• Filed: 12/28/2011
• Issued: 09/09/2014
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Lotte Advanced Materials Co., Ltd. (Lotte Chemical Corporation)
• Original Assignee: Cheil Industries Incorporated
• Inventors: Seo, Chang Min, Lee, Gyeong Mo
• Primary Examiner(s): Savage, Matthew O
• Assistant Examiner(s): Behrendt, Benjamin J
• Application Number:
  US13/338,557
• Publication Number:
  US 20120273409A1
• Time in Patent Office: 986 Days
• US Class Current: 210/490
• CPC Class Codes: B01D 2323/08 Specific temperatures applied
• CPC Class Codes: B01D 2323/42 Details of membrane preparation apparatus
• CPC Class Codes: B01D 2325/40 Fibre reinforced membranes
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/147 Microfiltration
• CPC Class Codes: B01D 67/0002 Organic membrane manufacture
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/087 Details relating to the spinning process
• CPC Class Codes: B01D 69/10 Supported membranes; Membrane supports
• CPC Class Codes: B01D 69/107 Organic support material
• CPC Class Codes: B01D 71/34 Polyvinylidene fluoride
• CPC Class Codes: B29C 70/222 the structure being shaped to form a three dimensional configuration
• CPC Class Codes: B29K 2027/16 PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2031/04 Polymers of vinyl acetate, e.g. PVAc, i.e. polyvinyl acetate
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2225/06 PS, i.e. polystyrene
• CPC Class Codes: B29K 2227/06 PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2227/16 PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2231/04 Polymers of vinyl acetate, e.g. PVAc, i.e. polyvinyl acetate
• CPC Class Codes: B29K 2233/08 Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
• CPC Class Codes: B29K 2267/00 : Use of polyesters or derivatives thereof as reinforcement
• CPC Class Codes: B29K 2269/00 : Use of PC, i.e. polycarbonates or derivatives thereof as reinforcement
• CPC Class Codes: B29K 2277/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as reinforcement
• CPC Class Codes: B29K 2309/08 : Glass
• CPC Class Codes: B29K 2427/16 : PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2431/04 : Polymers of vinyl acetate, e.g. PVAc, i.e. polyvinyl acetate
• CPC Class Codes: B29K 2469/00 : Use of PC, i.e. polycarbonates or derivatives thereof as filler
• CPC Class Codes: B29K 2627/16 : PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2631/04 : Polymers of vinyl acetate, e.g. PVAc, i.e. polyvinyl acetate
• CPC Class Codes: B29K 2669/00 : Use of PC, i.e. polycarbonates or derivatives thereof for preformed parts, e.g. for inserts
• CPC Class Codes: B29K 2827/16 : PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2831/04 : Polymers of vinyl acetate, e.g. PVAc, i.e. polyvinyl acetate
• CPC Class Codes: B29K 2869/00 : Use of PC, i.e. polycarbonates or derivatives thereof as mould material

Abstract

A hollow fiber membrane is formed by embedding a braid having a spiral open weave of monofilaments only, to avoid a “whiskering” problem common in prior art multifilament braid-supported tubular membranes. The open weave is characterized by contiguous, circumferential, rhomboid-shaped areas of polymer film separated by monofilaments. When the braid is supported on a plasticized PVA cable it can be infiltrated with membrane polymer which, when coagulated embeds the braid positioning it around the lumen. The spiral weave, free of any circumferentially constricting monofilament, when embedded in film, allows the membrane to be biaxially distensible. In other words, the membrane has “give” not only in the axial or longitudinal direction but also in the radial direction. “Give” in the radial direction permits soiled membranes to be backwashed under higher pressure than in a comparable braid which is not radially distensible.

Claims

1. An outside-in hollow fiber asymmetric membrane comprising, a tubular flexible braid of monofilament embedded as a monolayer in a tubular film of membrane polymer infiltrating the braid so as to form and reinforce the membrane'"'"'s lumen, the braid, free of multifilament yarn, comprising, from 6 to 24 separate monofilaments in the range from 25-250 denier (g/9000 meters), woven in a spiral open weave having an air permeability greater than 10 cc/sec/cm² at 1.378 kPa, to provide contiguous rhomboid areas of the membrane polymer bounded by monofilaments, the rhomboid areas having a pair of opposed acute included angles, and the spiral weave being woven with filaments at axially oppositely directed spiral angles in the range from 20°

-60°

from the longitudinal axis, so as to be free of a restricting circumferential filament allowing the braid and membrane to be biaxially distensible under pressure from within, prior to being damaged;

such that the asymmetric membrane is adapted for use as a microfiltration or ultrafiltration liquid separation membrane.

2. The asymmetric membrane of claim 1 wherein monofilament is selected from the group consisting of polyvinylidene fluoride, polycarbonate, polystyrene, polyester, polyolefin, polyamide, poly meta acrylate, poly vinyl chloride and glass fiber.

3. The asymmetric membrane of claim 1 wherein monofilaments overlying one another at intersections are movable relative to each other before the film is formed.

4. The asymmetric membrane of claim 1 wherein intersections of the monofilaments, wherein one overlies another, are the only locations where the monolayer has two superimposed monofilaments.

5. The asymmetric membrane of claim 1 wherein the volume of the monofilament in the monolayer of monofilament braid occupies a minor portion of the annular volume of the membrane.

6. The asymmetric membrane of claim 5 having an adhesive strength greater than 15 Kgf/cm², a bubble point greater than 4 bar and a greater than 95% rejection of 0.03 μ

m polystyrene beads in an aqueous dispersion.