Bimodal polypropylene for cast films or a metallized film wherein the polypropylene comprises two fractions which differ in the comonomer content

Patent metadata

Field	Value
Publication number	US-10280242-B2
Application number	US-201414888134-A
Country	US
Kind code	B2
Filing date	May 28, 2014
Priority date	May 29, 2013
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

The present application relates to a propylene ethylene random copolymer exhibiting two melting temperatures (Tm) which differ from each other.

First claim

What is claimed is:

1. A propylene ethylene random copolymer (R-PP), comprising a propylene ethylene random copolymer fraction (R-PP1) and a propylene ethylene random copolymer fraction (R-PP2) in a weight ratio [(R-PP1)/(R-PP2)] of 30/70 to 70/30 and not comprising an elastomeric phase,
wherein the propylene ethylene random copolymer has
(a) a melt flow rate MFR2 (230° C.) measured according to ISO 1133 from 5 to 15 g/10 min,
(b) an ethylene content from 1 to 10 wt.-%, based on the weight of the propylene ethylene random copolymer (R-PP), and
(c) exhibiting two melting temperatures (T m ) determined by differential scanning calorimetry (DSC) according to ISO 11357-3 which differ from each other,
wherein a xylene cold soluble (XCS) content of the propylene ethylene random copolymer (R-PP) is equal or below 12 wt.-%, and
(d) the ethylene content of the propylene ethylene random copolymer fraction (R-PP1) is equal to or differs from the ethylene content of the propylene ethylene random copolymer fraction (R-PP2).

2. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein the two melting temperatures (Tm) differ from each other by at least 4° C.

3. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein the higher melting temperature (Tm) ranges from 142 to 165° C., and the lower melting temperature (Tm) ranges from 125 to below 141° C.

4. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein
(d) the ethylene content of the propylene ethylene random copolymer fraction (R-PP1) differs from the ethylene content of the propylene ethylene random copolymer fraction (R-PP2) by 0-5 wt.-%.

5. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein
(e) the propylene ethylene random copolymer fraction (R-PP1) has an ethylene content of 1 to 8 wt.-%, and
(f) the propylene ethylene random copolymer fraction (R-PP2) has an ethylene content of 1 to 10 wt.-%.

6. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein MFR 2 (230° C.) of R-PP1 is equal to or differs from MFR 2 (230° C.) of R-PP2 by 0.1-3.0 g/10 min.

7. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein the propylene ethylene random copolymer (R-PP) is non-visbroken.

8. The propylene ethylene random copolymer (R-PP) according to claim 1 , obtainable by 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) propylene and ethylene, and
obtaining said propylene ethylene random copolymer fraction (R-PP1),
(B) transferring said propylene ethylene random copolymer fraction (R-PP1) and unreacted comonomers from the first reactor into a second reactor (R-2),
(C) feeding to said second reactor (R-2) propylene and ethylene,
(D) polymerizing propylene and ethylene in said second reactor (R-2) and in the presence of said propylene ethylene random copolymer fraction (R-PP1), and
obtaining said propylene ethylene random copolymer fraction (R-PP2), i.e. said propylene ethylene random copolymer (R-PP) comprising the propylene ethylene random copolymer fraction (R-PP1) and propylene ethylene random copolymer fraction (R-PP2),
wherein further
(i) the temperature in the first reactor (R-1) is of more than 65° C. to equal or below 95° C.,
(ii) the temperature in the second reactor (R-2) is preferably of equal or more than 75° C. to equal or below 100° C.,
(iii) in the first reactor (R-1) and second reactor (R-2) the polymerization takes place in the presence of a solid catalyst system (SCS) having a surface area measured according to ASTM D 3662 of less than 30 m 2 /g,
wherein further
(I) said solid catalyst system (SCS) comprises
(Ia) a transition metal selected from one of the groups 4 to 6 of the periodic table (IUPAC),
(Ib) a metal which is selected from one of the groups 1 to 3 of the periodic table (IUPAC), and
(Ic) an internal electron donor (ID).

9. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein the propylene ethylene random copolymer is suitable for the preparation of cast films.

10. The propylene ethylene random copolymer (R-PP) according to claim 1 , wherein the propylene ethylene random copolymer is suitable for the preparation of metallizable films.

11. A polypropylene composition comprising:
(a) 99 to 90 wt-% of a propylene ethylene random copolymer (R-PP),
(b) 1 to 10 wt-% of a high density polyethylene (HDPE) having a melt flow rate MFR2 (190° C.) of 15 to 45 g/10 min and a density of at least 940 kg/m 3 ,
(c) optionally additives, such as acid scavengers, antioxidants and/or antiblocking agents;
based on the total weight of the composition,
wherein the propylene ethylene random copolymer (R-PP) comprises a propylene ethylene random copolymer fraction (R-PP1) and a propylene ethylene random copolymer fraction (R-PP2) in a weight ratio [(R-PP1)/(R-PP2)] of 30/70 to 70/30 and does not comprise an elastomeric phase, and
wherein the propylene ethylene random copolymer has
(a) a melt flow rate MFR2 (230° C.) measured according to ISO 1133 from 5 to 15 g/10 min,
(b) an ethylene content from 1 to 10 wt.-%, based on the weight of the propylene ethylene random copolymer (R-PP), and
(c) exhibiting two melting temperatures (T m ) determined by differential scanning calorimetry (DSC) according to ISO 11357-3 which differ from each other,
wherein a xylene cold soluble (XCS) content of the propylene ethylene random copolymer (R-PP) is equal or below 12 wt.-%, and
(d) the ethylene content of the propylene ethylene random copolymer fraction (R-PP1) is equal to or differs from the ethylene content of the propylene ethylene random copolymer fraction (R-PP2).

12. The polypropylene composition according to claim 11 , being free of slip agent(s).

13. A cast film comprising the random propylene copolymer (R-PP) according to claim 1 .

14. A metallizable film comprising the polypropylene composition according to claim 11 .

15. A metallizable film according to claim 14 , further comprising a skin layer, a core layer, and a heat-sealing layer, the core layer is sandwiched between the skin layer and the heat-sealing layer, wherein the polypropylene composition is used for the skin layer.

16. The propylene ethylene random copolymer (R-PP) according to claim 1 , suitable in the preparation of polypropylene compositions suitable for the preparation of cast films and/or metallizable cast films.

17. The propylene ethylene random copolymer (R-PP) according to claim 16 , wherein the cast films or metallizable cast films are monolayer films, bilayer films, triple layer films or multilayer films.

18. A process for the preparation of a propylene ethylene random copolymer (R-PP) comprising a propylene ethylene random copolymer fraction (R-PP1) and a propylene ethylene random copolymer fraction (R-PP2), said 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) propylene and ethylene, and
obtaining said propylene ethylene random copolymer fraction (R-PP1),
(B) transferring said propylene ethylene random copolymer fraction (R-PP1) and unreacted comonomers from the first reactor into a second reactor (R-2),
(C) feeding to said second reactor (R-2) propylene and ethylene,
(D) polymerizing propylene and ethylene in said second reactor (R-2) and in the presence of said propylene ethy

Assignees

• Abu Dhabi Polymers Co Ltd Borouge Llc
• Borealis Ag

Inventors

• Priatmoko Joko
• Galiatsatos Vassilios

Classifications

• B32B2307/31

  Heat sealable · CPC title

• B32B2307/54

  Yield strength; Tensile strength · CPC title

• C08F2500/11

  Melt tension or melt strength · CPC title

• C08F210/06 Primary

  Propene · CPC title

• C08F2/34

  Polymerisation in gaseous state · CPC title