Polysulfone and poly(N-vinyl lactam) polymer alloy and fiber and filter materials made of the alloy

• US 7,641,055 B2
• Filed: 11/10/2005
• Issued: 01/05/2010
• Est. Priority Date: 11/10/2005
• Status: Active Grant

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Kalayci, Veli, Cardinal, Richard S., Ferrer, Ismael
• Primary Examiner(s): Menon; Krishnan S
• Application Number:
  US11/272,429
• Publication Number:
  US 20070102372A1
• Time in Patent Office: 1,517 Days
• Field of Search: None
• US Class Current: 210/500.41
• CPC Class Codes: B01D 39/02 Loose filtering material, e.g. loose fibres
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: Y10T 428/298 Physical dimension

Abstract

A polymer alloy has been developed comprising a polysulfone and a vinyl lactam polymer. The resulting alloy has excellent thermal characteristics and even in the presence of substantial quantities in vinyl lactam polymers, has solvent resistance to both organic and aqueous solvent materials. The materials, when dissolved in solvents, can be spun from a variety of solvents into a variety of useful fiber materials. The resulting fine fiber, microfiber and nanofiber materials have excellent thermal and chemical resistance for a variety of fiber applications. The polymer alloys of the invention can be spun into nanofiber mats that can act as a filtration media and can also be combined into conventional substrate materials for fabrication into filter structures.

Claims

1. A filter medium, the filter medium comprises a layer of fine fiber and a support, the fine fiber comprising a thermoplastic polymer alloy in a homogeneous composition comprising:

(a) an N-vinyl lactam polymer; and

(b) a polysulfone polymer;

wherein the alloy displays a single glass transition temperature (T_g), wherein said T_g is found at a temperature that ranges from about 180 to about 190°

C., wherein the fine fiber has a fiber diameter that ranges from about 0.01 to about 5 microns and the layer comprise a thickness of about 5 to 50 microns and a basis weight of up to about 200 g/m².

2. The filter medium of claim 1 wherein the medium comprises a support comprising a non-woven fabric and a fine fiber layer comprising a fiber diameter that ranges from about 0.05 to about 2 microns and the layer comprise a thickness of about 10 to 30 microns and a basis weight of up to about 0.50 to 150 g/m².

3. The medium of claim 1 wherein the fiber comprises greater than about 25 wt % of the N-vinyl lactam polymer.

4. The medium of claim 1 wherein the N-vinyl lactam polymer is a vinyl pyrrolidone polymer.

5. The medium of claim 3 wherein the polysulfone is a bisphenol-A polysulfone.

6. The medium of claim 1 wherein the polysulfone is a polysulfone copolymer.

7. The medium of claim 1 wherein the fiber comprises about 25 to 75 wt % of a polyvinyl pyrrolidone and about 25 to 75 wt % of the bisphenol-A-polysulfone.

8. The medium of claim 1 wherein the fiber comprises about 0.001 to 5 wt % of an inorganic salt alkali metal halide.

9. The medium of claim 1 wherein the inorganic salt comprises an alkali metal halide.

10. The fiber of claim 1 wherein fine fiber layer comprising a fiber diameter that ranges from about 0.05 to about 0.5 microns and the layer comprise a thickness of about 10 to 20 microns and a basis weight of up to about 1 to 100 g/m².