Micro/ultrafiltration membranes with a fixed pore size formed through irradiation with pulsed lasers and process for manufacturing the same

• US 4,923,608 A
• Filed: 12/16/1988
• Issued: 05/08/1990
• Est. Priority Date: 12/17/1987
• Status: Expired due to Fees

• Current Assignee: Akzo Nobel N.V. (Nouryon BV)
• Original Assignee: Akzo Nobel N.V. (Nouryon BV)
• Inventors: Flottmann, Thomas, Tretzel, Joachim
• Primary Examiner(s): Sever, Frank
• Application Number:
  US07/285,113
• Time in Patent Office: 508 Days
• Field of Search: 210/500.1, 210/500.21, 210/500.25, 210/500.26, 264/41, 29/163.8
• US Class Current: 210/500.25
• CPC Class Codes: B01D 2325/022 Asymmetric membranes
• CPC Class Codes: B01D 67/0025 by mechanical treatment, e.g. pore-stretching
• CPC Class Codes: B01D 67/0032 by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/02 Inorganic material
• CPC Class Codes: B01D 71/0213 Silicon
• CPC Class Codes: B23K 2103/30 Organic material
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/382 by boring
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: C03B 21/06 by flashing-off, burning-off or fusing C03B9/42 takes precedence
• CPC Class Codes: C03B 33/082 using a focussed radiation beam, e.g. laser C03B33/0855 takes precedence
• CPC Class Codes: C04B 2111/00801 Membranes; Diaphragms
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 38/0051 characterised by the pore size, pore shape or kind of porosity
• CPC Class Codes: C04B 41/0036 Laser treatment working by laser beam B23K26/00
• CPC Class Codes: Y10T 29/49604 Filter

Abstract

Flat membranes from foils of organic polymers, glass or ceramic materials have pores tapering in funnel-shaped fashion, with a fixed pore size and a pore size distribution of less than 10% and an arrangement of the pores in a pattern of adjacent rows, wherein the average pore diameters range from 0.05 to 10 μm and the pore patterns are evenly arranged in a regularly bounded area and, between the individual pores, have remaining webs with varying heights in the plane parallel to the increase in thickness of the foil material. It is manufactured through erosion of the pores by use of one or more intensity-modulated laser beams and continuous transport of the foil past the laser or lasers, with a pulse duration ranging from 1 to 1000 ns.

Claims

1. A flat membrane comprising a foil of organic polymers, glass or ceramic materials, with pores formed by at least one pulsed laser tapering in funnel-shaped fashion, and having a fixed pore size and a pore size distribution of less than 10% and an arrangement of the pores in a pattern of adjacent rows sufficient to provide a clear separation limit, wherein average diameters of said pores range from 0.05 to 10 μ

m and the pore patterns are evenly arranged in a regularly bounded area and have, between the individual pores, remaining ribs with varying heights in a direction of a thickness of the foil material sufficient to permit underwashing of retained parts of a filtered medium.

2. A flat membrane as set forth in claim 1, wherein the regularly bounded area is a square.

3. A flat membrane as set forth in claim 1, wherein the regularly bounded area is a rectangle.

4. A flat membrane as set forth in claim 1, wherein the regularly bounded area is a circle.

5. A flat membrane as set forth in claim 1, wherein the ribs are arranged with varying heights parallel in one direction.

6. A flat membrane as set forth in claim 1, wherein the ribs which are disposed perpendicularly to each other have alternately varying heights.

7. A flat membrane as set forth in claim 1, wherein the flat membrane is installed on a coarse-pored support material.

8. A process for manufacturing a flat membrane from a foil of organic polymers, glass or ceramic materials, comprising eroding pores in said membrane with at least one pulsed laser and continuously transporting the foil past said at least one laser, wherein a uniformly spatially intensity-modulated laser beam bounded by a regular area is pulsed onto the foil with a pulse duration ranging from 1 to 100 nanoseconds said membrane being sufficient to provided a clear separation limit, said pores being separated by ribs which are capable of providing underwashing of retained parts of a filtered medium.

9. A method as set forth in claim 8, wherein the uniform spatial intensity modulation is generated by crossed interference lines.

10. A method as set forth in claim 8, wherein the uniform spatial intensity modulation is generated by optical image formation of a shadow mask.

11. A method as set forth in claim 8, wherein the foil is mounted onto a coarse-pored support system prior to radiation with lasers.

12. A method as set forth in claim 8, wherein said foil further comprises a thin metal foil and the metal foil is provided with coarse-pored openings prior to or after said eroding step.