Process aid for metallocene catalyzed linear low density polyethylene polymers
View Patent ↗Extrusion processability of resin blends of a metallocene catalyzed linear low density polyethylene and a low density polyethylene is improved by introducing a process aid package comprising a fluoroelastomer having a Mooney viscosity (ML(1+10) at 121° C.) between 30 and 60 and an interfacial agent.
1. An extrudable composition comprising:
A) a resin blend comprising 1 to 99 weight percent, based on total weight of said resin blend, of a metallocene catalyzed linear low density polyethylene resin copolymer of ethylene and an α-olefin, said resin having a molecular weight distribution less than 3 and 99 to 1 weight percent, based on total weight of said resin blend, of a low density polyethylene resin homopolymer having a molecular weight distribution greater than 3;
B) 25 to 2000 ppm, based on total weight of said extrudable composition, of a fluoroelastomer having a Mooney viscosity ML(1+10) at 121° C. between 30 and 60; and
C) an interfacial agent in an amount resulting in a weight ratio of interfacial agent to fluoroelastomer between 0.1 and 0.9; wherein said extrudable composition contains 0 to 20 ppm ionomer.
2. An extrudable composition of claim 1 wherein said resin blend comprises 50 to 90 weight percent, based on total weight of said resin blend, of a metallocene catalyzed linear low density polyethylene resin and 50 to 10 weight percent, based on total weight of said resin blend, of a low density polyethylene resin.
3. An extrudable composition of claim 1 wherein said fluoroelastomer comprises copolymerized units selected from the group consisting of i) vinylidene fluoride/hexafluoropropylene; ii) vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene; iii) tetrafluoroethylene/propylene; and iv) tetrafluoroethylene/propylene/vinylidene fluoride.
4. An extrudable composition of claim 3 wherein said fluoroelastomer comprises copolymers of vinylidene fluoride/hexafluoropropylene.
5. An extrudable composition of claim 1 wherein said interfacial agent is selected from the group consisting of i) silicone-polyether copolymers; ii) aliphatic polyesters; iii) aromatic polyesters; iv) polyether polyols; v) amine oxides; vi) carboxylic acids; vii) fatty acid esters; and vii) poly(oxyalkylene) polymers.
6. An extrudable composition of claim 5 wherein said interfacial agent is an aliphatic polyester.
7. An extrudable composition of claim 6 wherein said aliphatic polyester is a polycaprolactone having a number average molecular weight between 1000 and 32000.
8. An extrudable composition of claim 5 wherein said interfacial agent is a poly(oxyalkylene) polymer.
9. An extrudable composition of claim 8 wherein said poly(oxyalkylene) polymer is a polyethylene glycol.