Extrusion coating process for improved adhesion to metal(lized) substrates
A process for extrusion coating metal foils and metallized films which utilizes a mixture of silanated and non-silanated ethylene polymers is provided.
1 . A process for the production of extrusion coated substrates comprising:
(a) providing a silanated ethylene polymer having silane functionality incorporated in the polymer chain by copolymerization or attached to the polymer chain by grafting;
(b) providing a non-silanated ethylene polymer;
(c) combining (a) and (b) to obtain a mixture comprised of 1 to 70 wt. % (a) and 30 to 99 wt. % (b);
(d) melt blending the mixture obtained from (c);
(e) extrusion coating at least one side of a substrate with the melt blended product produced in (d).
2 . The process of claim 1 wherein the substrate is a metal foil or metallized film.
3 . The process of claim 1 wherein (b) the melt blended product obtained from (d) is pelletized prior to extrusion coating.
4 . The process of claim 1 wherein (a) has from 0.1 to 20 wt. % vinyltrialkoxysilane of the formula H 2 C═CHSi—(OR) 3 where R is a C 1-4 alkyl group incorporated by copolymerization or grafting.
5 . The process of claim 4 wherein (a) contains 0.5 to 7.5 wt. % VTMOS or VTEOS.
6 . The process of claim 4 wherein (b) is selected from the group consisting of ethylene homopolymers, ethylene-C 3-8 α-olefin copolymers, ethylene-vinylacetate copolymers, ethylene-acrylic acid copolymers and mixtures thereof.
7 . The process of claim 6 wherein (b) is an ethylene homopolymer.
8 . The process of claim 7 wherein (b) is an LDPE homopolymer.
9 . The process of claim 6 wherein (b) is a copolymer of ethylene with butene-1, hexene-1 or octene-1.
10 . The process of claim 6 wherein (b) is an ethylene-vinylacetate copolymer having a vinyl acetate content of 5 to 40 wt. %.
11 . The process of claim 6 wherein (b) is an ethylene-acrylic acid copolymer having an acrylic acid content of 1 to 18 wt. %.
12 . The process of claim 6 wherein (b) is a mixture of HDPE and one or more other ethylene (co)polymers present at a weight ratio of 10:1 to 1:10.
13 . The process of claim 12 wherein (b) is a mixture of HDPE and LDPE present at a weight ratio from 5:1 to 1:5.
14 . The process of claim 6 wherein the mixture (c) is comprised of 5 to 50 wt. % (a) and 50 to 95 wt. % (b).
15 . An extrusion coated metal foil or metallized film produced by the process of claim 1 .
16 . Extrusion coated aluminum foil produced by the process of claim 1.