Multilayer protective liner

1. A thermoplastic multilayer structure in the form of a tubular article or pipe liner comprising at least three layers,

(a) a first surface layer having a thickness of about 6.3 to about 51 mm comprising a soft thermoplastic composition consisting of an ionomer of an ethylene acid terpolymer comprising an E/X/Y copolymer wherein E represents copolymerized units of ethylene, X is present in an amount of about 2 to about 30 weight % of the E/X/Y polymer and represents copolymerized units of a C 3-8 α,β-ethylenically unsaturated carboxylic acid and Y is present in from 3 to 45 weight % of the E/X/Y copolymer and represents copolymerized units of a softening comonomer selected from alkyl acrylate, alkyl methacrylate, wherein the alkyl groups have from 1 to 8 carbon atoms, or vinyl acetate, wherein about 40 to about 75% of the carboxylic acid groups in the copolymer are neutralized to salts wherein the cations consist of zinc cations with melting point in a range from about 60 to about 220 ° C., with flexural modulus determined at 21 ° C. according to ASTM D790 of less than or equal to 90 MPa and Shore D hardness (ASTM D2240) from about 30 to about 50;

(b) a second surface layer comprising a thermoplastic polymer composition containing acid functionality, an ionomer thereof, or anhydride functionality with flexural modulus determined at 21 ° C. according to ASTM D790 of less than 100 MPa and melting point in a range from about 60 to about 100 ° C., wherein the composition comprises

(1) a polyolefin graft copolymer comprising a trunk polymer comprising polyethylene, polypropylene, styrene-ethylene-butene-styrene triblock copolymer, polybutadiene or a copolymer comprising copolymerized units of ethylene and copolymerized units of vinyl acetate, alkyl acrylate or alkyl methacrylate; wherein the alkyl groups have from 1 to 8 carbon atoms, wherein the trunk polymer is modified by grafting thereto a cyclic anhydride of C 4 -C 8 unsaturated acids; or

(2) an ethylene dicarboxylic random copolymer comprising copolymerized units of ethylene and copolymerized units of a dicarboxylic comonomer selected from the group consisting of cyclic anhydrides of C 4 -C 8 unsaturated acids monoesters of C 4 -C 8 unsaturated acids having at least two carboxylic acid rows diesters of C 4 -C 8 unsaturated acids having at least two carboxylic acid groups, and mixtures thereof, wherein the ethylene dicarboxylic copolymer comprises from about 0.3 to about 20 weight % copolymerized units of dicarboxylic comonomer, based on the weight of the random copolymer; or

(3) an ethylene acid terpolymer comprising an E/X/Y copolymer wherein E represents copolymerized units of ethylene, X is present in an amount of about 2 to about 30 weight % of the E/X/Y polymer and represents copolymerized units of a C 3-8 α,β-ethylenically unsaturated carboxylic acid, and Y is present in from 3 to 45 weight % of the E/X/Y copolymer and represents copolymerized units of a softening comonomer selected from alkyl acrylate, alkyl methacrylate, wherein the alkyl groups have from 1 to 8 carbon atoms, or vinyl acetate; or an ionomer thereof wherein about 40 to about 75% of the carboxylic acid groups in the terpolymer are neutralized to salts wherein the cations consist of zinc cations; or

(4) an ethylene acid E/Z dipolymer wherein E represents copolymerized units of ethylene, and Z is present in an amount of about 10 to about 25 weight % of the E/Z diolymer and represents cool merized units of a C 3-8 α,β-ethylenically unsaturated carboxylic acid; and

(c) at least one interior layer of a material selected from the group consisting of thermoplastic resin, fiber reinforcement, and metal and combinations thereof, wherein the thermoplastic resin comprises a composition with flexural modulus determined at 21 ° C. according to ASTM D790 of greater than 80 MPa, melting point in a range from about 75 to about 150 ° C., and moisture vapor permeation value less than 2 g-mil/100in 2 -day; wherein the thermoplastic resin comprises

(i) an ionomer of an E/W ethylene acid dipolymer wherein E represents copolymerized units of ethylene, W is present in an amount of about 2 to about 30 weight % of the E/W polymer and represents copolymerized units of a C 3-8 α,β-ethylenically unsaturated carboxylic acid, wherein about 40 to about 75% of the carboxylic acid groups in the dipolymer are neutralized to salts wherein the cations consist of zinc cations; or

(ii) a polyethylene homopolymer, polyethylene copolymer, polypropylene homopolymer or polypropylene copolymer,

wherein the second surface layer is adhered to the interior of a metal pipe having a thickness of about 6.3 to about 51 mm.

2. The multilayer structure of claim 1 wherein the interior layer comprises the ionomer of the E/W ethylene acid dipolymer.

3. The multilayer structure of claim 2 wherein the second surface layer comprises the ionomer of an ethylene acid terpolymer.

4. The multilayer structure of claim 1 wherein the interior layer consists of a polyethylene homopolymer, polyethylene copolymer, polypropylene homopolymer or polypropylene copolymer.

5. The multilayer structure of claim 4 comprising, in order, the first surface layer comprising the ionomer of the ethylene acid terpolymer, a first tie layer, the interior layer consisting of high density polyethylene or polypropylene, a second tie layer and the second surface layer comprising the ionomer of an ethylene acid terpolymer.

6. The multilayer structure of claim 1 , wherein the C 3-8 α,β-ethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid.

7. The multilayer structure of claim 6 wherein X is methacrylic acid, present in an amount from 5 to 20 weight % of the E/X/Y copolymer and Y is butyl acrylate, present in an amount from 10 to 30 weight % of the E/X/Y copolymer.

8. The multilayer structure of claim 1 wherein the second surface layer comprises (1).

9. The multilayer structure of claim 1 wherein the second surface layer comprises (3).

10. The multilayer structure of claim 9 wherein X is methacrylic acid, present in an amount from 5 to 20 weight % of the E/X/Y terpolymer and Y is butyl acrylate, present in an amount from 10 to 30 weight % of the E/X/Y copolymer.

11. The multilayer structure of claim 9 wherein (3) is the E/X/Y terpolymer.

12. The multilayer structure of claim 11 wherein X is methacrylic acid, present in an amount from 5 to 20 weight % of the E/X/Y terpolymer and Y is butyl acrylate, present in an amount from 10 to 30 weight % of the E/X/Y copolymer.

13. The multilayer structure of claim 1 wherein (3) is the ionomer of the E/X/Y terpolymer.