Adhesive blends for styrene polymers and articles
Tie-layer adhesives for styrene polymer resins are provided. The adhesive blend compositions are comprised of ethylene-vinyl acetate copolymer, styrene-butadiene-styrene triblock copolymer, ethylene-propylene rubber and graft-modified polyethylene.
1 . An adhesive composition comprising:
(a) 30 to 55 wt. %, based on the total weight of the composition, ethylene-vinyl acetate copolymer having a vinyl acetate content from 10 to 30 wt. %;
(b) 18.5 to 32.5 wt. %, based on the total weight of the composition, styrene-butadiene-styrene triblock polymer containing from 40 to 47.5 wt. % bound styrene;
(c) 0.5 to 20 wt. %, based on the total weight of the composition, ethylene-propylene rubber or ethylene-propylene-diene rubber containing greater than 50 wt. % ethylene; and
(d) 0.5 to 25 wt. %, based on the total weight of the composition, graft-modified polyethylene.
2 . The adhesive composition of claim 1 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content from 12 to 28 wt. %.
3 . The adhesive composition of claim 2 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content from 15 to 20 wt. % and constitutes 32.5 to 52.5 wt. % of the adhesive composition.
4 . The adhesive composition of claim 1 wherein the styrene-butadiene-styrene triblock polymer contains from 42.5 to 45 wt. % bound styrene.
5 . The adhesive composition of claim 4 wherein the styrene-butadiene-styrene triblock polymer contains less than 1 wt. % diblock and constitutes 20 to 30 wt. % of the adhesive composition.
6 . The adhesive composition of claim 1 wherein the ethylene-propylene rubber or ethylene-propylene diene rubber contains 60 wt. % or more ethylene and constitutes 3 to 18 wt. % of the adhesive composition.
7 . The adhesive composition of claim 1 wherein the graft-modified polyethylene is an ethylene-α-olefin copolymer grafted with 0.5 to 3 wt. % ethylenically unsaturated carboxylic acid or acid derivative.
8 . The adhesive composition of claim 7 wherein the graft-modified polyethylene is HDPE or LLDPE copolymer resin grafted with maleic anhydride and constitutes 2.5 to 20 wt. % of the adhesive composition.
9 . A multi-layer film or sheet comprising a styrene polymer layer and a tie-layer adhesively bonded thereto, said tie-layer comprising an adhesive composition comprising 30 to 55 wt. %, based on the total weight of the composition, ethylene-vinyl acetate copolymer having a vinyl acetate content from 10 to 30 wt. %; 18.5 to 32.5 wt. %, based on the total weight of the composition, styrene-butadiene-styrene triblock polymer containing from 40 to 47.5 wt. % bound styrene; 0.5 to 20 wt. %, based on the total weight of the composition, ethylene-propylene rubber or ethylene-propylene-diene rubber containing greater than 50 wt. % ethylene; and 0.5 to 25 wt. %, based on the total weight of the composition, graft-modified polyethylene.
10 . The multi-layer film or sheet of claim 9 wherein the styrene polymer is selected from the group consisting of polystyrene, high impact polystyrene and mixtures of polystyrene and high impact polystyrene.
11 . The multi-layer film or sheet of claim 10 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content from 12 to 28 wt. %; the styrene-butadiene-styrene triblock polymer contains from 42.5 to 45 wt. % bound styrene; the ethylene-propylene rubber or ethylene-propylene diene rubber contains 60 wt. % or more ethylene; and the graft-modified polyethylene is an ethylene-α-olefin copolymer grafted with 0.5 to 3 wt. % ethylenically unsaturated carboxylic acid or acid derivative.
12 . The multi-layer film or sheet of claim 11 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content from 15 to 20 wt. % and constitutes 32.5 to 52.5 wt. % of the adhesive composition; the styrene-butadiene-styrene triblock polymer contains less than 1 wt. % diblock and constitutes 20 to 30 wt. % of the adhesive composition; the ethylene-propylene rubber or ethylene-propylene-diene rubber constitutes 3 to 18 wt. % of the adhesive composition; and the graft-modified polyethylene is an HDPE or LLDPE copolymer resin grafted with maleic anhydride and constitutes 2.5 to 20 wt. % of the adhesive composition.
13 . The multi-layer film or sheet of claim 10 comprising a further polyolefin layer and wherein the tie-layer is disposed between the polyolefin layer and the styrene polymer layer.
14 . The multi-layer film or sheet of claim 13 wherein the polyolefin layer is HDPE or LDPE.
15 . The multi-layer film or sheet of claim 10 comprising a further layer of ethylene-vinyl alcohol copolymer and wherein the tie-layer is disposed between the ethylene-vinyl alcohol copolymer layer and the styrene polymer layer.