Propylene copolymer with excellent optical properties

Patent metadata

Field	Value
Publication number	US-2021347971-A1
Application number	US-201917273711-A
Country	US
Kind code	A1
Filing date	Sep 9, 2019
Priority date	Sep 26, 2018
Publication date	Nov 11, 2021
Grant date	—

Abstract

The present invention is directed to a polypropylene composition (P) comprising a first random propylene copolymer (A) and a second random propylene copolymer (B), said first random propylene copolymer (A) and said second random propylene copolymer (B) being copolymers of propylene and 1-hexene. Further, the present invention is directed to a blown film comprising said polypropylene composition (P).

First claim

1 - 15 . (canceled)

16 . A polypropylene composition (P), comprising at least 90.0 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 a 1-hexene having a 1-hexene content in the range of 0.1 to 3.0 wt.-%, 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), wherein the copolymer (C) has an overall 1-hexene content in the range of 3.8 to 10.0 wt.-%, and wherein the copolymer (C) has a xylene soluble content (XCS) in the range of 8.0 to 30.0 wt.-%.

17 . The polypropylene composition (P) according to claim 16 , fulfilling 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).

18 . The polypropylene composition (P) according to claim 16 , wherein the copolymer (C) has a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 0.4 to 12.0 g/10 min.

19 . The polypropylene composition (P) according to claim 16 , 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.

20 . The polypropylene composition (P) according to claim 16 , wherein the copolymer (C) has an amount of 2,1 erythro regio-defects of at least 0.4 mol.-%.

21 . The polypropylene composition (P) according to claim 16 , 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 0.3 to 12.0 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 0.2 to 9.0 g/10 min.

22 . The polypropylene composition (P) according to claim 16 , wherein the copolymer (C) comprises 35.0 to 65.0 wt.-% of the first random propylene copolymer (A) and 35.0 to 65.0 wt.-% of the second random propylene copolymer (B), based on the overall weight of the copolymer (C).

23 . The polypropylene composition (P) according to claim 16 , wherein the copolymer (C) fulfills in-equation (2)

4.5
≤

C
⁢

⁢
6
⁢

(
C
)

C
⁢

⁢
6
⁢

(
A
)

*

[
A
]

[
C
]

≤

9
.
0

(
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].

24 . The polypropylene composition (P) according to claim 16 , wherein the copolymer (C) has an amount of hexane hot solubles (HHS) measured according to FDA 177.1520 equal to or below 1.5 wt.-%.

25 . An article, comprising at least 90.0 wt.-% of the polypropylene composition (P) according to claim 16 .

26 . The article according to claim 25 , wherein the article is a film.

27 . The article according to claim 26 , wherein the film has
i) a haze before steam sterilization determined according to ASTM D 1003-00 measured on a 50 μm blown film below 10.0%, and ii) a haze after steam sterilization determined according to ASTM D 1003-00 measured on a 50 μm blown film below 12.0%.

28 . The article according to claim 26 , wherein the article is a sealing layer in a multi-layer film.

29 . A process for the preparation of a copolymer (C) according to claim 16 , wherein the process is a sequential polymerization process comprising at least two reactors connected in series, wherein said process comprises the steps of
(A) polymerizing in a first reactor (R-1) which is a slurry reactor (SR), propylene and 1-hexene, and obtaining a first random propylene copolymer (A), (B) transferring said first random propylene copolymer (A) and unreacted comonomers of the first reactor (R-1) in a second reactor (R-2) which is a gas phase reactor (GPR-1), (C) feeding to said second reactor (R-2) propylene and 1-hexene, (D) polymerizing in said second reactor (R-2) and in the presence of said first random propylene copolymer (A) propylene and 1-hexene obtaining a second random propylene copolymer (B), said first random propylene copolymer (A) and said second random propylene copolymer (B) form the copolymer (C) of the polypropylene composition (P), wherein further in the first reactor (R-1) and the second reactor (R-2) the polymerization takes place in the presence of a solid catalyst system (SCS), said solid catalyst system (SCS) comprises a transition metal compound of formula (I)
R n (Cp) 2 MX 2   (I)

wherein each Cp independently is an unsubstituted or substituted and/or fused cyclopentadienyl ligand, substituted or unsubstituted indenyl or substituted or unsubstituted fluorenyl ligand; wherein the optional one or more substituent(s) is independently selected from the group consisting of halogen, hydrocarbyl, C 3 -C 12 -cycloalkyl which contains 1, 2, 3 or 4 heteroatom(s) in the ring moiety, C 6 -C 20 -heteroaryl, C 1 -C 20 -haloalkyl, —SiR″ 3 , —OSiR″ 3 , —SR″, —PR″ 2 , OR″ and —NR″ 2 , wherein each R″ is independently a hydrogen or hydrocarbyl selected from the group consisting of C 1 -C 20 -alkyl, C 2 -C 20 -alkenyl, C 2 -C 20 -alkynyl, C 3 -C 12 -cycloalkyl, and C 6 -C 20 -aryl; or in case of —NR″ 2 , the two substituents R″ can form a five- or six-membered ring, together with the nitrogen atom to which they are attached; R is a bridge of 1-2 C-atoms and 0-2 heteroatoms, wherein the he

Assignees

• Borealis Ag

Inventors

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

Classifications

• C08L2201/10

  Transparent films; Clear coatings; Transparent materials · CPC title

• C08F2410/01

  Additive used together with the catalyst, excluding compounds containing Al or B · CPC title

• C08F4/65927

  two cyclopentadienyl rings being mutually bridged · CPC title

• C08F210/06 Primary

  Propene · CPC title

• C08L2203/162

  sealable films · CPC title