Functionalized nonwoven article
View Patent ↗A grafted nonwoven substrate is disclosed having average fiber sizes of 0.7 to 15 microns, and a void volume of 50 to 95%, and a polymer comprising anionic monomer units grafted to the surface of the nonwoven substrate. The article may be used as a filter element to purify or separate target materials, such as monoclonal antibodies (MAb), from a fluid mixture.
1. A method of preparing a functionalized nonwoven article comprising the steps of:
a. providing a nonwoven substrate having average fiber diameter of 1 to 6 micrometers, and a void volume of 50 to 95%;
b. exposing the nonwoven substrate to ionizing radiation in an inert atmosphere, and
c. imbibing the exposed substrate with a solution comprising grafting anionic monomers to graft polymerize said monomers to the surface of the nonwoven substrate so as to form a grafted polymer on the surface of the substrate, thus providing a functionalized nonwoven article, said imbibing solution comprising:
a) 80 to 98 wt. % of grafting anionic monomers;
b) 2 to 20 wt. % of grafting poly(alkylene oxide) monomers;
c) 0 to 10 wt. % of second hydrophilic monomers.
2. The method of claim 1 wherein the nonwoven substrate has a tensile strength of at least 4.0 Newtons prior to grafting.
3. The method of claim 1 wherein the grafting anionic monomers have a general formula:
where
R 1 is H or CH 3 ;
X is —O— or —NR 1 —,
Y is a straight or branched chain alkylene, and
Z is an anionic group.
4. The method of claim 1 wherein the grafting poly(alkylene oxide) monomers are of a formula:
Z-Q-(CH(R 1 )—CH 2 -Q) m -R 4 ,
wherein Z is a polymerizable ethylenically unsaturated moiety, R 1 is a H or CH 3 , R 4 is a H, a C 1 to C 4 alkyl group, aryl group, or combinations thereof, m is from 2 to 100, and Q is —O—.
5. The method of claim 1 wherein the imbibing solution further comprises a second hydrophilic grafting monomer.
6. The method of claim 1 wherein the imbibing solution comprises an aqueous/water-soluble organic solvent solution, wherein said organic solvent contains no tertiary hydrogen atoms.
7. The method of claim 1 wherein the imbibing solution comprises no polyethylenically unsaturated monomers.
8. The method of claim 1 wherein the weight of the grafting monomers of the imbibing solution is 0.5 to 5 times the weight of the nonwoven substrate.
9. The method of claim 1 wherein the weight of the grafting monomers in the imbibing solution is 5 wt % to 30 wt %, based on a total weight of the imbibing solution.
10. The method of claim 1 wherein the grafted polymer is of the formula:
-(M anionic ) w -(M PEG ) x -(M c ) y
wherein
-(M anionic ) w - represent the grafted anionic monomer having w polymerized monomer units where w is at least 2,
-(M PEG ) x represents the polymerized poly(alkylene oxide) monomer having x polymerized monomer units, where x is at least one;
-(M c ) y represents the polymerized hydrophilic monomer having y polymerized monomer units, where y may be zero.
11. The method of claim 1 wherein the nonwoven substrate is exposed to 1 to 200 kGys of ionizing radiation.
12. The method of claim 1 wherein exposure to e-beam energy generates free radical sites on the surfaces of the nonwoven substrate, and initiating graft polymerization of said monomers.
13. The method of claim 1 comprising the further step of removing the excess monomer solution, and drying.
14. The method of claim 1 wherein the nonwoven substrate is prepared from a hydrophilic thermoplastic polymer.
15. The method of claim 1 wherein the nonwoven substrate has a surface area of 15 to 50 m 2 per square meter of nonwoven substrate.
16. The method of claim 1 wherein the nonwoven substrate has a mean pore size of 1-40 microns according to ASTM F 316-03.
17. The method of claim 1 wherein the nonwoven substrates have a solidity of less than 20%.
18. The method of claim 1 wherein the nonwoven substrate is a spunlaid, spunlaced, hydroentangled, wet-laid electrospun or a meltblown nonwoven substrate.