Polyamide-metal laminates

1. A metal part having a tie layer (B) on the surface of a metal layer (A), in which the tie layer (B) comprises:

B1) a polymer comprising carboxylic acid groups and

B2) an amino-silane comprising a primary amine and at least one hydroxyl group;

in which at least two carboxylic acid groups in polymer (B1) are adjacent each other, and the molar ratio of carboxylic acid groups in (B1) to primary amine group in (B2) is from 1:0.8 to 1:12.

2. A polyamide-metal laminate comprising the metal part of claim 1 , and further comprising (C) a polyamide composition formed on the surface of the tie layer.

3. The polyamide-metal laminate of claim 2 , wherein the content of the adjacent two carboxylic acid groups in polymer (B1) is 2 weight % or more based on the total weight % of polymer (B1).

4. The polyamide-metal laminate of claim 2 , wherein polymer (B1) comprises one or more polymers selected from the group consisting of poly(butadiene-maleic acid) copolymers, propylene-maleic acid copolymers, ethylene-maleic acid copolymers, ethylene-maleic anhydride copolymers, propylene-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, polymaleic acid(s), maleic anhydride grafted ethylene octene copolymers, maleic anhydride grafted ethylene butene copolymers, and maleic anhydride grafted ethylene propylene copolymers.

5. The polyimide-metal laminate of claim 2 , wherein amino-silane (B2) is represented by the formula (I):

where R 1 , R 2 , and R 3 are independently selected from H, C1 to C6 linear, branched, or cyclic alkyl groups; R 4 is H; R 5 is independently selected from H and —(CH 2 ) y —NH 2 ; x and y independently range from 1 to 6; and at least one of R 1 , R 2 , and R 3 is H.

6. The polyimide-metal laminate of claim 2 , wherein the metal layer (A) is aluminum.

7. The polyimide-metal laminate of claim 6 , wherein the aluminum has hydroxyl groups on the surface of the aluminum.

8. A composition suitable for use in forming the tie layer of the metal part of claim 1 , said composition comprising;

B1) the polymer comprising carboxylic acid groups,

B2) the amino-silane comprising a primary amine and at least one hydroxyl group and

B3) a solvent.

9. The composition of claim 8 , wherein its pH is 5 or more.

10. The composition of claim 8 , wherein the solvent is water.

11. A method to laminate a polyamide on the surface of the metal part of claim 1 , wherein the metal part is aluminum, comprising the steps of:

(i) preparing an aluminum part in which the surface of the aluminum is cleaned,

(ii) applying a composition to form a tie layer on the surface of the aluminum part, said composition comprising

B1) a polymer comprising carboxylic acid groups,

B2) an amino-silane comprising a primary amine and at least one hydroxyl group, and

B3) a solvent;

wherein at least two carboxylic acid groups in the polymer are adjacent each other, and the molar ratio of carboxylic acid groups in the polymer to primary amine group in the amino-silane is from 1:0.8 to 1:12; then

(iii) laminating a polyamide composition on the tie layer under heating at a temperature that is at least the temperature at which the polyamide melts.

12. The method of claim 11 , wherein the solvent is water.

13. The method of claim 11 , further comprising the step of evaporating the solvent before laminating the polyamide composition.

14. An article comprising the polyamide-metal laminate of claim 2 .

15. The article of claim 14 selected from the group consisting of a tube, a hose, a water pump housing, an oil filter housing and a transmission housing.

16. An article comprising the metal part of claim 1 .

17. The article of claim 16 , selected from the group consisting of a tube, a hose, a water pump housing, an oil filter housing and a transmission housing.