Polypropylene composition

Patent metadata

Field	Value
Publication number	US-11292900-B2
Application number	US-201816768330-A
Country	US
Kind code	B2
Filing date	Dec 18, 2018
Priority date	Dec 20, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

Polypropylene composition comprising a heterophasic polypropylene (HECO) and a bimodal metallocene linear low-density polyethylene (mLLDPE), as well as articles obtained from said polypropylene composition. The present invention is further related to the use of a bimodal metallocene linear low-density polyethylene (mLLDPE) as modifier for heterophasic polypropylenes (HECOs) to improve impact strength and optics.

First claim

The invention claimed is:

1. A polypropylene composition, comprising
(A) a heterophasic polypropylene (HECO), said heterophasic polypropylene comprising a matrix (M) being a propylene homopolymer and an elastomeric propylene-ethylene copolymer dispersed in said matrix (M), and
(B) a bimodal metallocene linear low-density polyethylene (mLLDPE), said bimodal metallocene linear low-density polyethylene (mLLDPE)
(a) being a terpolymer of ethylene and two different comonomers selected from alpha olefins having from 4 to 10 carbon atoms and
(b) being produced with a metallocene catalyst and
(c) having a density of 915 to 930 kg/m 3 (according to ISO 1183), and
(C) optionally a polypropylene homopolymer with a melt flow rate MFR2 (ISO 1133; 230° C.; 2.16 kg) in the range of 0.5 to 100.0 g/10 min and/or
(D) optionally an alpha nucleating agent.

2. The polypropylene composition according to claim 1 comprising
component (A) in an amount of from 95.0 to 55.0 wt %,
component (B) in an amount of from 5.0 to 45.0 wt %,
component (C) in an amount of from 0.0 to 6.0 wt % and
component (D) in an amount from 0.0 to 1.0 wt %, based on the total weight of the composition.

3. The polypropylene composition according to claim 1 , which has:
a haze according to ASTM D 1300-00 determined on 1 mm plaques below 35.0% and
a Charpy notched Impact strength (NIS, ISO 179 1eA determined at 23° C.) of at least 15.0 kJ/m 2 .

4. The polypropylene composition according to claim 1 , which has an optomechanical ability (OMA) according to formula

O
⁢

⁢
M
⁢

⁢
A

=

Flex
⁢

⁢

Modulus
⁢

[
MPa
]

*

NIS
⁡

[

kJ

⁢

m
2

]

Haze
⁢

⁢

(

1
⁢

⁢
mm

)

⁢

[
%
]

of at least 500 or more;
wherein NIS refers to the Charpy notched impact strength measured according to ISO 179 1eA at +23° C.

5. The polypropylene composition according to claim 1 , wherein the heterophasic polypropylene (HECO) has a xylene cold soluble (XCS) fraction in the range of from 5.0 to 25.0 wt %, as determined at 25° C., wherein said xylene cold soluble (XCS) fraction has an ethylene content in the range of from 8.0 to 70.0 wt % and an intrinsic viscosity (iV) from 1.0 to 5.0 dl/g and a crystalline fraction in the range of from 75.0 to 95.0 wt %, wherein said crystalline fraction has an ethylene content in the range of from 0.0 to 5.0 wt % and an intrinsic viscosity (iV) from 1.0 to 5.0 dl/g, as determined according to CRYSTEX QC method, ISO 6427-B.

6. The polypropylene composition according to claim 1 , wherein the heterophasic polypropylene (HECO) is prepared by a sequential polymerization process in the presence of a metallocene-based catalyst.

7. The polypropylene composition according to claim 1 , wherein the bimodal metallocene linear low-density polyethylene (mLLDPE) comprises at least
(i) an ethylene polymer component (A) having an MFR2 of 1.0 to 10.0 g/10 min (according to ISO 1133 at 190° C. under 2.16 kg load) and
(ii) an ethylene polymer component (B) having an MFR2 of 0.2 to 0.9 g/10 min (according to ISO 1133 at 190° C. under 2.16 kg load).

8. The polypropylene composition according to claim 1 , wherein the bimodal metallocene linear low-density polyethylene (mLLDPE) (B) comprises an ethylene polymer component (A′) and an ethylene polymer component (B′), wherein the ethylene polymer component (A′) has a lower amount (mol %) of comonomer than the ethylene polymer component (B′).

9. The polypropylene composition according to claim 8 , wherein the amount of comonomer in the ethylene polymer component (A′) is from 0.05 to 0.9 mol %, and the amount of comonomer in the ethylene polymer component (B′) is from 1.0 to 5.0 mol %.

10. The polypropylene composition according to claim 1 , wherein the bimodal metallocene linear low-density polyethylene (mLLDPE) has a total amount of comonomers present in the bimodal metallocene linear low-density polyethylene in the range of 1.0 to 6.0 mol %.

11. An article comprising the polypropylene composition according to claim 1 .

12. The article according to claim 11 , wherein the article is an unoriented mono-layer film, comprising at least 90 wt % of the polypropylene composition.

13. The article according to claim 11 , wherein the article is a moulded article.

Assignees

• Borealis Ag

Inventors

• Gahleitner Markus
• Wang Jingbo
• Bernreitner Klaus
• Leskinen Pauli

Classifications

• C08F210/12

  with conjugated diolefins, e.g. butyl rubber · CPC title

• C08F4/6492

  containing aliphatic unsaturation · CPC title

• C08L23/12 Primary

  Polypropene · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08L23/16

  Ethylene-propylene or ethylene-propylene-diene copolymers · CPC title