C2C3 random copolymer

Patent metadata

Field	Value
Publication number	US-11485845-B2
Application number	US-202017595839-A
Country	US
Kind code	B2
Filing date	May 20, 2020
Priority date	May 29, 2019
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

New C2C3 random copolymers, which combine low sealing initiation temperature (SIT), high hot-tack, low C6-solubles, good optical properties and an improved stiffness/impact balance, which are particularly suited for preparing blown films. The present invention is furthermore related to the manufacture of said copolymers and to their use, as well as to the blown films comprising such C2C3 random copolymers.

First claim

The invention claimed is:

1. A C 2 C 3 random copolymer (A) consisting of 50.0 to 85.0 wt % of polymer fraction (A-1) having
(i) an ethylene content in a range of from 2.0 to 5.2 wt % and
(ii) a melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 in a range of from 0.5 to 5.0 g/10 min and 15.0 to 50.0 wt % of polymer fraction (A-2) having
(i) an ethylene content in a range of from 5.5 to 10.0 wt % and
(ii) a melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 in a range of from 0.1 to 3.0 g/10 min,
wherein the melt flow rate MFR 2 (230° C./2.16 kg) of polymer fraction (A-2) is lower than the melt flow rate MFR 2 (230° C./2.16 kg) of polymer fraction (A-1), and
wherein the C 2 C 3 random copolymer has
(a) a total ethylene content in a range of from 3.0 to 7.5 wt %;
(b) a melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 in a range of from 0.5 to 5.0 g/10 min and
(c) a melting temperature Tm as determined by DSC according to ISO 11357 of from 110° C. to 135° C.

2. The C 2 C 3 random copolymer according to claim 1 , wherein the C 2 C 3 random copolymer (A) has an amount of hexane solubles (C6 solubles, FDA) measured on a 100 μm thick blown film according to FDA 177.1520 in a range of from 0.1 to 2.0 wt %.

3. The C 2 C 3 random copolymer composition according to claim 1 , wherein the C 2 C 3 random copolymer (A) is obtained in the presence of a metallocene catalyst.

4. A process for producing the C 2 C 3 random copolymer according to claim 1 , comprising the following steps
a) polymerizing in a first reactor (R1) propylene and ethylene, to obtain polymer fraction (A-1) of the C 2 C 3 random copolymer (A),
b) transferring said polymer fraction (A-1) and unreacted comonomers of the first reactor (R1) into a second reactor (R2),
c) feeding to said second reactor (R2) propylene and ethylene,
d) polymerizing in said second reactor (R2) and in the presence of said polymer fraction (A-1) propylene and ethylene, to obtain polymer fraction (A-2),
wherein said polymer fraction (A-1) and said polymer fraction (A-2) form the C 2 C 3 random copolymer (A),
wherein the polymerizing takes place in the presence of a metallocene catalyst comprising (i) a complex of formula (I):

wherein M is zirconium or hafnium;
each X is a sigma ligand;
L is a divalent bridge selected from —R′ 2 C—, —R′ 2 C—CR′ 2 —, —R′ 2 Si—, —R′ 2 Si—SiR′ 2 —, or —R′ 2 Ge—, wherein each R′ is independently a hydrogen atom, C 1 —C 20 -hydrocarbyl, tri(C 1 -C 20 -alkyl)silyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl or C 7 -C 20 -alkylaryl;
R 2 and R 2′ are each independently a C 1 -C 20 -hydrocarbyl radical optionally containing one or more heteroatoms from groups 14-16;
R 5 , is a C 1 -C 20 -hydrocarbyl group containing one or more heteroatoms from groups 14-16 optionally substituted by one or more halogen atoms;
R 6 and R 6′ are each independently hydrogen or a C 1-20 -hydrocarbyl group optionally containing one or more heteroatoms from groups 14-16; R 7 is hydrogen or C 1-20 -hydrocarbyl group optionally containing one or more heteroatoms from groups 14-14, and R 7′ is hydrogen;
Ar and Ar′ each are independently an aryl or heteroaryl group having up to 20 carbon atoms optionally substituted by one or more groups R 1 ;
each R 1 is a C 1-20 -hydrocarbyl group or two R 1 groups on adjacent carbon atoms taken together can form a fused 5 or 6 membered non aromatic ring with the Ar or Ar′ group, said ring being itself optionally substituted with one or more groups R 4 ; wherein each R 4 is a C 1-20 -hydrocarbyl group;
and (ii) a cocatalyst comprising at least one or two compounds of a group 13 metal.

5. The process according to claim 4 , wherein as cocatalyst (ii) a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst is used and the catalyst is supported on a silica support.

6. An article, comprising the C 2 C 3 random copolymer (A) according to claim 1 .

7. The article according to claim 6 , wherein the article is a blown film.

8. The article according to claim 7 , wherein the blown film comprises
(i) a sealing initiation temperature (SIT) (determined as described in the experimental part) in a range of from 80° C. to below 112° C.,
(ii) a hot-tack force determined as described in the experimental part on 50 μm blown film) of 1.8 N up to 5.0 N,
(iii) a haze (determined according to ASTM D1003-00 on blown film with a thickness of 50 μm) in a range of from 0.1 to 8.0%, and
(iv) a clarity (determined according to ASTM D1003-00 on blown film with a thickness of 50 μm) of at least 80.0% up to 100.0%.

9. The article according to claim 8 having a tensile modulus determined according to ISO 527-3 at 23° C. on blown films with a thickness of 50 μm in machine direction and in transverse direction in a range of 300 to 700 MPa.

10. The article according to claim 8 , having a dart-drop impact (DDI) strength determined according to ASTM D1709, method A on a 50 μm blown film of 10 g to 200g.

11. The article according to claim 8 having an optomechanical ability (OMA) determined according to the formula given below:

O
⁢

⁢
M
⁢

⁢
A

=

Tensile
⁢

⁢
Modulus
⁢

⁢

(
MD
)

⁡

[

M
⁢
P
⁢
a

]

*
D
⁢

⁢
D
⁢

⁢

I
⁡

(
g
)

Haze
⁢

⁢

(

50
⁢

⁢
μm

)

⁡

[
%
]

Assignees

• Borealis Ag

Inventors

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

Classifications

• C08F2/001

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title

• B29L2031/7128

  Bags, sacks, sachets (tea bags B29L2031/7122; medical bags B29L2031/7148) · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08F210/06 Primary

  Propene · CPC title

• C08L23/142

  at least partially crystalline copolymers of propene with other olefins · CPC title