Propylene copolymer composition with excellent optical and mechanical properties

Patent metadata

Field	Value
Publication number	US-12404393-B2
Application number	US-201917273687-A
Country	US
Kind code	B2
Filing date	Aug 7, 2019
Priority date	Sep 26, 2018
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

The present invention is directed to a polypropylene composition (P) comprising a copolymer (C) of propylene and 1-hexene comprising a first random propylene copolymer (A) of propylene and a 1-hexene, and a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer (A) as well as a plastomer (PL) being an elastomeric copolymer of ethylene and at least one C 4 to C 10 α-olefin. Further, the present invention is directed to an article comprising said polypropylene composition (P) and the use of said polypropylene composition (P) as a sealing layer in a multi-layer film.

First claim

The invention claimed is:

1. A polypropylene composition (P), comprising
a) 80.0 to 99.0 wt. %, based on the overall weight of the polypropylene composition (P), of a copolymer (C) of propylene and 1-hexene, comprising
i) a first random propylene copolymer (A) of propylene and 1-hexene, the first random propylene copolymer (A) having a 1-hexene content in the range of 1.0 to 2.5 wt.-% and having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.3 to 1.9 g/10 min, and
ii) a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer (A), the second random propylene copolymer (B) having a 1-hexene content in the range of 6.5 to 10.0 wt.-% and having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.1 to 1.2 g/10 min,
wherein the copolymer (C) has a 1-hexene content in the range of 4.0 to 7.0 wt.-%, has a xylene soluble content (XCS) in the range of 10.0 to 26.0 wt.-%, wherein a 1-hexene content of the xylene soluble fraction C6 (XCS) is in the range of 3.0 to 8.0 wt.-%, and a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.4 to 1.4 g/10 min, and copolymer (C) is free of any elastomeric polymer component and is not a heterophasic polypropylene, and

b) 1.0 to 20.0 wt. %, based on the overall weight of the polypropylene composition (P), of a plastomer (PL) which is an elastomeric copolymer of ethylene and at least one C 4 to C 10 α-olefin having a density in the range of 0.860 to 0.930 g/cm 3 ;
the polypropylene composition (P) has a melting temperature (Tm) measured according to ISO 11357-3 of at least 120° C., and a difference between the melting temperature (Tm) and a heat sealing initiation temperature (SIT) fulfilling the equation Tm−SIT>20° C., and
the polypropylene composition (P) exhibits a dart-drop strength (DDI) of 300 to 1700 g, determined according to ASTM D1709, method A, when measured on a 50 μm blown film, and a haze value before steam sterilization of 1.9 to 6.5%, as determined according to ASTM D-1003-00, on a 50 μm blown film.

2. The polypropylene composition (P) according to claim 1 , wherein the copolymer (C) has an amount of 2,1 erythro regio-defects of at least 0.4 mol. %.

3. The polypropylene composition (P) according to claim 1 , wherein the weight ratio between the first random propylene copolymer (A) and the second random propylene copolymer (B) within the copolymer (C) is in the range of 30:70 to 70:30.

4. The polypropylene composition (P) according to claim 1 , wherein the copolymer (C) fulfils in-equation (1)
MFR( C )/MFR( A )≤1.0  (1),

wherein MFR(A) is the melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in [g/10 min] of the first random propylene copolymer (A) and MFR(C) is the melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in [g/10 min] of the copolymer (C).

5. The polypropylene composition (P) according to claim 1 , wherein the copolymer (C) fulfils in-equation (2)

4.5
≤

C
⁢
6
⁢

(
C
)

C
⁢
6
⁢

(
A
)

*

❘
"\[LeftBracketingBar]"

A

❘
"\[RightBracketingBar]"

❘
"\[LeftBracketingBar]"

C

❘
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≤
9.

(
2
)

wherein
C6(A) is the 1-hexene content of the first random propylene copolymer (A) based on the total weight of the first random propylene copolymer (A) [in wt. %];
C6(C) is the 1-hexene content of the copolymer (C) based on the total weight of the copolymer (C) [in wt. %]; and
[A]/[C] is the weight ratio between the first random propylene copolymer (A) and the copolymer (C) [in g/g].

6. The polypropylene composition (P) according to claim 1 , wherein the plastomer (PL) has a density in the range of 0.865 to 0.920 g/cm 3 .

7. The polypropylene composition (P) according to claim 1 , wherein the plastomer (PL) is a copolymer of ethylene and 1-octene.

8. The polypropylene composition (P) according to claim 1 , wherein
i) the first random propylene copolymer (A) has a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 1.0 to 1.6 g/10 min, and/or
ii) the second random propylene copolymer (B) has a melt flow rate MFR 2 (230°° C., 2.16 kg) determined according to ISO 1133 in the range of 0.8 to 1.1 g/10 min.

9. An article comprising at least 90.0 wt. % of a polypropylene composition (P), the polypropylene composition (P) comprising
a) 80.0 to 99.0 wt. %, based on the overall weight of the polypropylene composition (P), of a copolymer (C) of propylene and 1-hexene, comprising
i) a first random propylene copolymer (A) of propylene and 1-hexene, the first random propylene copolymer (A) having a 1-hexene content in the range of 1.0 to 2.5 wt.-% and having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.3 to 1.9 g/10 min, and
ii) a second random propylene copolymer (B) of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer (A), the second random propylene copolymer (B) having the 1-hexene content in the range of 6.5 to 10.0 wt.-% and having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.7 to 1.2 g/10 min,
wherein the copolymer (C) has the 1-hexene content in the range of 4.0 to 7.0 wt.-%, has a xylene soluble content (XCS) in the range of 10.0 to 26.0 wt. %, wherein the 1-hexene content of the xylene soluble fraction C6 (XCS) is in the range of 3.0 to 8.0 wt.-%, and has a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.4 to 1.4 g/10 min, and copolymer (C) is free of any elastomeric polymer component and is no heterophasic polypropylene, and

b) 1.0 to 20.0 wt. %, based on the overall weight of the polypropylene composition (P), of a plastomer (PL) which is an elastomeric copolymer of ethylene and at least one C 4 to C 10 α-olefin

Assignees

• Borealis Ag

Inventors

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

Classifications

• C08L23/20

  having four to nine carbon atoms · CPC title

• C08L23/14 Primary

  Copolymers of propene (C08L23/16 takes precedence) · CPC title

• C08L23/0807

  with unsaturated hydrocarbons only containing four or more carbon atoms · CPC title

• C08F4/65927

  two cyclopentadienyl rings being mutually bridged · CPC title

• B29K2023/14

  Copolymers of polypropylene (B29K2023/16 takes precedence) · CPC title