Block composites and impact modified compositions
Embodiments of the invention provide block composites comprising a soft copolymer, a hard polymer and a block copolymer having a soft segment and a hard segment, wherein the hard segment of the block copolymer is the same composition as the hard polymer in the block composite and the soft segment of the block copolymer is the same composition as the soft copolymer of the block composite and their use as impact modifiers.
1. A formulated composition comprising:
a) polypropylene;
b) a compatibilizer; and,
c) an elastomer
wherein the composition exhibits an Izod strength in kJ/m 2 as measured by ASTM D256 or ISO180 at 0° C. or 23° C. that is at least 10% higher than that of the composition without (b); and exhibits a flexural modulus that is less than 10% reduced as compared to that of the composition without (b)
wherein the compatibilizer comprises a block composite wherein the block composite comprises a soft copolymer, a hard polymer and a diblock copolymer having a soft segment and a hard segment, wherein the hard segment of the block copolymer is the same composition as the hard polymer in the block composite and the soft segment of the block copolymer is the same composition as the soft copolymer of the block composite; and wherein the block composite has an Mw/Mn of 1.7 to 3.5, the blocks of the diblock copolymers are joined end-to-end and the hard polymer comprises propylene units present in an amount greater than 90 mol percent.
2. The composition of claim 1 wherein (b) has a Tm>100° C. and the composition has a dispersed rubber weight average particle size of <1 μm.
3. The composition of claim 1 wherein (b) is a block composite having a Block Composite Index≧0.10.
4. The composition of claim 3 wherein the block composite comprises a diblock having an isotactic polypropylene block and an ethylene-propylene block.
5. The composition of claim 4 wherein the isotactic polypropylene block is present in an amount of 25 wt % to 75 wt % of the diblock.
6. The composition of claim 4 wherein the ethylene content of the ethylene-propylene block is 40 wt % to 85 wt %.
7. The composition of claim 3 wherein the block composite has a melt flow rate at 230° C. and 2.16 kg of 0.5 to 8 dg/min.
8. The composition of claim 1 wherein the block composite is present in an amount of 0.5 wt % to 20 wt % of the weight of the composition and the composition has a ductile to brittle transition temperature of at least 2° C. less as compared to the composition without (b).
9. The composition of claim 1 wherein the polypropylene is selected from the group consisting of low density polypropylene, high density polypropylene, high melt strength polypropylene, high impact polypropylene, isotactic polypropylene, syndiotactic polypropylene and combinations thereof.
10. An article comprising the composition of claim 1 .
11. The composition of claim 1 wherein the elastomer is selected from the group consisting of ethylene/α-olefin random copolymers, ethylene/α-olefin block interpolymers, hydrogenated block copolymers and combinations thereof.