Multilayer shrink film with polystyrene and polyethylene layers
View Patent ↗A multilayer shrink film and methods of making same comprising one or more polyethylenic layers, one or more polystyrenic layer and polystyrene compatibilizing layers situate between each polyethylenic layer and polystyrenic layer wherein the polystyrene compatibilizing layers comprise less than 1% by weight substantially random interpolymer. The multilayer shrink films of the invention are produced using film biaxial orienting means.
1. A five layer shrink film comprising:
a first outer polyethylenic layer;
a second outer polyethylenic layer;
a core polystyrenic layer comprising from 70% to 75% by weight styrene homopolymer or α-methylstyrene homopolymer, from 10% to 15% by weight polystyrene toughener, from 10% to 20% by weight adhesive resin, and from 5% to 6% by weight slip additive;
a first polystyrene compatibilizing layer between the core polystyrenic layer and the first outer polyethylenic layer; and
a second polystyrene compatibilizing layer between the core polystyrenic layer and the second outer polyethylenic layer;
wherein the polystyrene compatabilizing layers comprise less than 1% by weight substantially random interpolymer.
2. The film of claim 1 wherein the first and second polyethylenic layers comprise at least 80% linear low density polyethylene copolymer.
3. The film of claim 2 wherein the linear low density polyethylene copolymer is a copolymer comprising from 1% to 10% by weight 1 -octene monomer.
4. The film of claim 1 wherein the polystyrene toughener is selected from the group consisting of styrene-isoprene diblock copolymer, styrene-isoprene triblock copolymer, and blends of styrene-isoprene diblock copolymer and styrene-isoprene triblock copolymer.
5. The film of claim 1 wherein the slip additives in the polystyrenic layer are selected from the group consisting of primary amides, secondary amides, ethylenebisamides and 13-docosenamide.
6. The film of claim 1 wherein each of the first and second polystyrenic compatibilizing layers comprise from 70% to 90% by weight linear low density polyethylene copolymer and from 5% to 20% by weight of an adhesive resin used as a polystyrene compatibilizing agent.
7. The film of claim 6 wherein the adhesive resin is selected from the group consisting of styrene-ethylene butylene-styrene block copolymer, anhydride-modified ethylene vinyl acetate, styrene-butadiene block copolymer, styrene-butadiene rubber, butadiene rubber, styrene-isoprene block copolymer, hydrogenated styrene-isoprene block copolymer, and styrene-butadiene-methyl methacrylate copolymer.
8. The film of claim 1 wherein the core polystyrenic layer comprises α-methylstyrene homopolymer.
9. The film of claim 1 wherein the core polystyrenic layer comprises styrene homopolymer.
10. A five layer shrink film comprising:
a first outer polyethylenic layer comprising 15% to 25% by weight of the film;
a second outer polyethylenic layer comprising 15% to 25% by weight of the film;
a core polystyrenic layer comprising 30% to 50% by weight of the film, the polystyrenic layer comprising from 70% to 75% by weight of the layer styrene homopolymer or α-methylstyrene homopolymer, from 10% to 15% by weight of the layer polystyrene toughener, from 10% to 20% by weight of the layer adhesive resin, and from 5% to 6% by weight of the layer slip additive;
a first polystyrene compatibilizing layer between the core polystyrenic layer and the first outer polyethylenic layer comprising 10% to 25% by weight of the film;
a second polystyrene compatibilizing layer between the core polystyrenic layer and the second outer polyethylenic layer comprising 10% to 25% by weight of the film;
wherein the first and second polystyrene compatabilizing layers comprise less than 1% by weight substantially random interpolymer; and
wherein each of the first and second polystyrene compatabilizing layers comprise 5% to 20% by weight of the layer anhydride-modified ethylene vinyl acetate.
11. A five layer shrink film comprising:
a first outer polyethylenic layer comprising 15% to 25% by weight of the film;
a second outer polyethylenic layer comprising 15% to 25% by weight of the film;
a core polystyrenic layer comprising 30% to 50% by weight of the film;
a first polystyrene compatibilizing layer between the core polystyrenic layer and the first outer polyethylenic layer comprising 10% to 25% by weight of the film;
a second polystyrene compatibilizing layer between the core polystyrenic layer and the second outer polyethylenic layer comprising 10% to 25% by weight of the film;
wherein the polystyrenic layer comprises 70% to 75% by weight of the layer styrene homopolymer or α-methylstyrene homopolymer, 10% to 15% by weight of the layer polystyrene toughener, 10% to 20% by weight of the layer adhesive resin and from 5% to 6% by weight of the layer slip additive;
wherein the first and second polystyrene compatabilizing layers together comprise less than 1% by weight interpolymer; and
wherein the first and second polystyrene compatabilizing layers each comprise 5% to 20% by weight of the layer styrene-ethylene butylene-styrene block copolymer.