METHOD FOR PREPARING A SELECTIVELY PERMEABLE PROTECTIVE STRUCTURE

1 . A method for preparing a selectively permeable multilayer structure or article comprising:

(1) preparing a first composition comprising

(i) one or more ethylene acid copolymers; and

(ii) one or more organic acids; wherein at least 50% of the combined acidic groups in the acid copolymer and the organic acid are nominally neutralized to salts with metal ions and at least 50% of the metal ions are alkali metal ions;

(2) melt blending the first composition with a terpolymer of ethylene, acrylic acid or methacrylic acid, and an alkyl acrylate or alkyl methacrylate;

and optionally with one or more ethylene-containing polymers selected from the group consisting of polyethylene (PE) homopolymers, copolymers of ethylene and an α-olefin, copolymers of ethylene and a diolefin, and ethylene copolymers obtained from copolymerization of ethylene with at least one polar monomer selected from the group consisting of vinyl acetate, acrylic ester, methacrylic ester and carbon monoxide, wherein the ethylene-containing polymer wherein the ethylene-containing polymer does not comprise a carboxylic acid comonomer, to provide a second composition in a molten condition;

(3) contacting a substrate with the molten second composition to adhere, embed, or impregnate the melted composition to the substrate or adhere, embed, or impregnate the substrate to the molten second composition to provide a coated substrate;

(4) cooling the coated substrate to allow the molten second composition to cool and solidify.

2 . The method of claim 1 wherein the substrate comprises textile or porous sheet material.

3 . The method of claim 2 wherein the substrate is one or more porous films, flash spun non-woven fabrics, woven fabrics of synthetic fibers, natural fibers or combinations thereof, scrims, or filter materials.

4 . The method of claim 3 wherein the substrate is a woven fabric of synthetic fibers, natural fibers or combinations thereof.

5 . The method of claim 1 wherein at least 50% of the metal ions are sodium ions.

6 . The method of claim 1 wherein at least 50% of the metal ions are potassium ions.

7 . The method of claim 1 wherein the ethylene-containing polymer is selected from the group consisting of ethylene copolymers obtained from copolymerization of ethylene with at least one polar monomer selected from the group consisting of vinyl acetate, acrylic ester, methacrylic ester and carbon monoxide.

8 . The method of claim 7 wherein the ethylene-containing polymer is an ethylene/alkyl acrylate or ethylene/alkyl methacrylate copolymer.

9 . The method of claim 1 wherein the second composition comprises

(a) 30 to 99 weight %, based on the combination of (a), (b) and (c), of a blended combination of

(1) 70 to 90 weight %, based on the combination of (1) and (2), of one or more E/W ethylene acid copolymers or ionomers of the acid copolymers wherein E represents copolymerized units of ethylene, X is present in about 2 to about 35 weight % of the copolymer and represents copolymerized units of at least one C 3 to C 8 α,β-ethylenically unsaturated carboxylic acid;

(2) 10 to 30 weight %, based on the combination of (1) and (2), of one or more organic acids having from 4 to 36 carbon atoms, or salts thereof; wherein at least 50% of the combined acidic groups in the E/W copolymer and the organic acid are nominally neutralized to salts with metal ions; wherein at least 50% of the metal ions are alkali metal ions;

(b) 1 to 30 weight %, based on the combination of (a), (b) and (c), of E/X/Y ethylene acid terpolymers wherein E represents copolymerized units of ethylene, X is present in about 2 to about 35 weight % of the copolymer and represents copolymerized units of acrylic acid or methacrylic acid, and Y is present in about 1 to about 35 weight % of the copolymer and represents copolymerized units of alkyl acrylate or alkyl methacrylate; and

(c) 0 to 60 weight %, based on the combination of (a), (b) and (c), of one or more second ethylene-containing polymer selected from the group consisting of polyethylene homopolymers, copolymers of ethylene and an α-olefin, copolymers of ethylene and a diolefin, and ethylene copolymers obtained from copolymerization of ethylene with at least one polar monomer selected from the group consisting of vinyl acetate, acrylic ester, methacrylic ester and carbon monoxide, wherein the second ethylene-containing polymer does not comprise a carboxylic acid comonomer; wherein (a), (b) and (c) total 100 weight %.

10 . The method of claim 9 wherein the ethylene-containing polymer is selected from the group consisting of ethylene copolymers obtained from copolymerization of ethylene with at least one polar monomer selected from the group consisting of vinyl acetate, acrylic ester, methacrylic ester and carbon monoxide.

11 . The method of claim 10 wherein the ethylene-containing polymer is an ethylene/alkyl acrylate or ethylene/alkyl methacrylate copolymer.

12 . The method of claim 7 wherein the second composition comprising (a), (b) and optionally (c) has greater adhesion to the substrate than a corresponding composition comprising (a) that does not comprise (b), the other components being identical.

13 . The method of claim 1 wherein the second composition has a moisture vapor permeation value of at least 200 g-mil/m 2 /24 h measured at 37.8° C. and 100% relative humidity according to ASTM F-1249 and high water-entry pressure.

14 . The method of claim 1 wherein the selectively permeable structure has a moisture vapor transmission rate of at least 50 g/m 2 /24 h measured at 37.8° C. and 100% relative humidity according to ASTM F-1249.