Patent Application

App. No. 12/583,547

Abstract

Claims (22)

1 . A polyolefin composition comprising a single-site linear low density polyethylene (mLLDPE) and an elastoplastic polypropylene present in an amount from 1 wt % to 30 wt % of the total composition.

2 . The composition of claim 1 , wherein the elastoplastic polypropylene comprises from 30 wt % to 90 wt % of a polyolefin elastomer and from 10 wt % to 60 wt % of a propylene homopolymer or propylene random copolymer.

3 . The composition of claim 1 , wherein the elastoplastic polypropylene has a flexural modulus less than 200 MPa (ISO 178/A), or a Shore D hardness (ISO 868) less than 40 points, or both.

4 . The composition of claim 1 , wherein the mLLDPE has a density within the range of 0.910 g/cm 3 to 0.930 g/cm 3 .

5 . The composition of claim 4 , wherein the mLLDPE has a density within the range of 0.920 g/cm 3 to 0.930 g/cm 3 .

6 . The composition of claim 2 , wherein the propylene random copolymer comprises 85 wt % or more of propylene based on the random copolymer.

7 . The composition of claim 6 , wherein the propylene random copolymer comprises from 85 wt % to 99 wt % of propylene and from 1 wt % to 15 wt % of ethylene, 1-butene, or a mixture thereof.

8 . The composition of claim 2 , wherein the polyolefin elastomer is selected from ethylene-propylene based elastomers, ethylene-butene based elastomers, or mixtures thereof.

9 . The composition of claim 2 , wherein the elastoplastic polypropylene comprises from 65 wt % to 80 wt % of the polyolefin elastomer and from 20 wt % to 35 wt % of the propylene homopolymer or the propylene random copolymer.

10 . The composition of claim 1 , wherein the elastoplastic polypropylene comprises:

(a) from 10 wt % to 50 wt % of a homopolymer of propylene with isotactic index greater than 80, or a copolymer of propylene and a comonomer selected from the group consisting of ethylene, C 4 —C 8 α-olefins, and mixtures thereof, which comprises greater than 85 wt % of propylene and has an isotactic index greater than 80;

(b) from 5 wt % to 20 wt % of a copolymer of ethylene and one or more C 3 —C 8 α-olefins; and

(c) from 40 wt % to 80 wt % of a copolymer of ethylene and one or more C 3 —C 8 α-olefins, which comprises from 20 wt % to 40 wt % of ethylene, is soluble in xylene at ambient temperature, and has an intrinsic viscosity from 1.5 to 5.5 dl/g.

11 . A film comprising the composition of claim 1 .

12 . The film of claim 11 , having a thickness greater than 1 mil, 1% secant machine-direction (MD) modulus greater than 35000 psi, MD tear strength greater than 1000 grams, and dart drop impact strength greater than 750 grams.

13 . A method for improving the processability and physical property of mLLDPE, said method comprising blending the mLLDPE with from 5 wt % to 30 wt % of an elastoplastic polypropylene based on the blend.

14 . The method of claim 13 , wherein the mLLDPE has a density within the range of 0.910 g/cm 3 to 0.930 g/cm 3 .

15 . The method of claim 14 , wherein the mLLDPE has a density within the range of 0.920 g/cm 3 to 0.930 g/cm 3 .

16 . The method of claim 13 , wherein the elastoplastic polypropylene comprises:

(a) from 10 wt % to 50 wt % of a homopolymer of propylene with isotactic index greater than 80, or a copolymer of propylene and a comonomer selected from the group consisting of ethylene, C 4 —C 8 α-olefins, and mixtures thereof, which comprises greater than 85 wt % of propylene and has an isotactic index greater than 80;

(b) from 5 wt % to 20 wt % of a copolymer of ethylene and one or more C 3 —C 8 α-olefins; and

(c) from 40 wt % to 80 wt % of a copolymer of ethylene and one or more C 3 —C 8 α-olefins, which comprises from 20 wt % to 40 wt % of ethylene and is soluble in a xylene at ambient temperature, and has an intrinsic viscosity from 1.5 to 5.5 dl/g.

Assignments (10)