Polyolefin-metal laminate
View Patent ↗A laminate and a process for making it are disclosed. The laminate comprises a metal substrate and a polymer layer that adheres to at least one plasma-treated surface of the metal substrate. The polymer layer comprises a blend of a first polyolefin and a grafted polyolefin. The laminate can be prepared by plasma-treating at least one surface of a metal substrate and extruding onto the plasma-treated surface a polymer layer comprising a blend of a first polyolefin and a grafted polyolefin.
1. A polyolefin-metal laminate comprising a metal substrate and a polymer layer that adheres to at least one plasma-treated surface of the metal substrate, wherein the polymer layer comprises a blend of a first polyolefin and a grafted polyolefin.
2. The laminate of claim 1 wherein the substrate comprises a metal selected from the group consisting of aluminum, nickel, copper, iron, and alloys thereof.
3. The laminate of claim 2 wherein the metal is aluminum.
4. The laminate of claim 1 wherein the plasma is generated in a gas comprising greater than 70% by volume of a noble gas selected from the group consisting of helium, neon, and argon.
5. The laminate of claim 1 prepared by extrusion coating wherein the blend is melted in an extruder and exposed to ozone gas prior to contacting the polymer layer with the plasma-treated surface of the metal substrate.
6. The laminate of claim 1 having an interlayer adhesion greater than 1.20 pounds per inch when measured according to ASTM D-1876.
7. The laminate of claim 6 wherein the interlayer adhesion is greater than 1.30 pounds per inch.
8. The laminate of claim 7 wherein the first polyolefin is LDPE.
9. The laminate of claim 1 wherein the first polyolefin is polyethylene.
10. The laminate of claim 1 wherein the grafted polyolefin comprises LLDPE grafted with maleic anhydride.
11. The laminate of claim 1 wherein the blend comprises from 0.5 to 20 wt. % of the grafted polyolefin.
12. The laminate of claim 11 wherein the blend comprises from 1 to 10 wt. % of the grafted polyolefin.
13. The laminate of claim 1 wherein the grafted polyolefin incorporates from 0.1 to 5 wt. % of an unsaturated carboxylic acid or an unsaturated carboxylic acid derivative.
14. A process for making a polyolefin-metal laminate, said process comprising: (a) plasma-treating at least one surface of a metal substrate; and (b) extruding onto the plasma-treated surface a polymer layer comprising a blend of a first polyolefin and a grafted polyolefin.