Multimodal random heterophasic polypropylene composition
The present invention provides a soft multimodal random heterophasic polypropylene composition (m-Raheco) with improved stiffness and impact behaviour while maintaining optical properties. The multimodal random heterophasic polypropylene composition (m-Raheco) is suitable as material for injection moulding, e.g. for thin walled injection moulded articles. The present invention also describes specific propylene random copolymers as modifiers or compatibilizers in polyolefins and their according use.
1. A multimodal random heterophasic polypropylene composition (m-Raheco) having a Melt Flow Rate (MFR230/2.16), determined according to ISO1133, of 1.0-100 g/10 min and is characterised by comprising
70.0-94.0 wt.-% of a first propylene random copolymer (P1) and
1.0-15.0 wt.-% of a second propylene random copolymer (P2) being different from the first propylene random copolymer (P1), and
5.0-20.0 wt.-% of an elastomeric propylene copolymer (E) wherein the multimodal random heterophasic polypropylene composition (m-Raheco) comprises
17.0-32.0 wt.-% of a fraction soluble in cold xylene (XCS), wherein said fraction soluble in cold xylene (XCS) having
a comonomer content Co(XCS) of 65.0-85.0 wt.-% and
an intrinsic viscosity (IV) in the range of at least 2.5 dl/g when measured in Decalin according to ISO 1628.
2. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 , which is characterised by at least three glass transition temperatures Tg1, Tg2 and Tg3, wherein either
at least two of said glass transition temperatures are below 0° C. and/or
at least three glass transition temperatures are below +10° C., and/or
the difference between the two lowest glass transition temperatures is at least 10 K or more.
3. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 wherein the second propylene random copolymer (P2) is characterised by
a comonomer content of 4.0-15.0 wt.-% and
10.0-30.0 wt.-% of a fraction soluble in cold xylene (XCS).
4. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 , wherein the elastomeric propylene copolymer (E) comprises a first elastomeric propylene copolymer (E1) and a second elastomeric propylene copolymer (E2), wherein the first elastomeric propylene copolymer (E1) is characterised by having
a1) an intrinsic viscosity (IV) in the range of 2.6-4.5 and/or
b1) a comonomer content Co(XCS) of 62.0-85.0 wt.-%,
and the second elastomeric propylene copolymer (E2), is characterised (independently of the first) by having
a2) an intrinsic viscosity (IV) in the range of 1.2-2.5 dl/g and/or
b2) a comonomer content Co(XCS) of 18.0-33.0 wt.-%.
5. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 ,
wherein the multimodal random heterophasic polypropylene composition (m-Raheco) is produced by mixing a first heterophasic propylene copolymer (Heco 1) and second heterophasic propylene copolymer (Heco 2),
wherein the first heterophasic propylene copolymer (Heco 1) comprises a first propylene random copolymer (P1) as a first matrix (PM1) and a first elastomeric propylene copolymer (E1) dispersed therein, and
wherein the second heterophasic propylene copolymer (Heco 2) comprises the second propylene random copolymer (P2) as a second matrix (PM2) and a second elastomeric propylene copolymer (E2) dispersed therein.
6. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 5 , comprising
85.0-99.0 wt.-% of the first heterophasic propylene copolymer (Heco 1) and
1.0-15.0 wt.-% of the second heterophasic propylene copolymer (Heco 2).
7. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 6 , wherein
the first heterophasic propylene copolymer (Heco 1) is produced in the presence of a metallocene based catalyst and/or
the second heterophasic propylene copolymer (Heco 2) is produced in the presence of a Ziegler-Natta-catalyst.
8. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 5 , wherein
the first heterophasic propylene copolymer (Heco 1) is produced in the presence of a metallocene based catalyst and/or
the second heterophasic propylene copolymer (Heco 2) is produced in the presence of a Ziegler-Natta-catalyst.
9. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 , characterised by:
a tensile modulus of at least 750 MPa when measured according to ISO527 and/or
a Charpy notched impact Strength (NIS) of at least 4.0 kJ/m 2 when measured according to ISO179/1eA at +23° C. and/or
a optomechanical ability (OMA) of at least 40, wherein the optomechanical ability (OMA) is determined according the formula:
O
M
A
=
tensile
modulus
[
MPa
]
*
N
I
S
[
kJ
m
2
]
Haze
(
1
mm
)
[
%
]
.
10. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 , characterised by:
tensile modulus of at least 750 MPa and
either or both of:
a puncture based optomechanical ability at +23° C. (punc-OMA +23) of at least 80 or more when determined according to the formula
punc
-
O
M
A
+
23
=
Tensile
modulus
[
MPa
]
*
(
Puncture
Energy
+
23
°
C
.
)
[
J
]
Haze
(
1
mm
)
[
%
]
and/or
a puncture based optomechanical ability at −20° C. (punc-OMA −20) of at least 40 or more when determined according to the formula
punc
-
O
M
A
-
20
=
Tensile
modulus
[
MPa
]
*
(
Puncture
Energy
-
20
°
C
.
)
[
J
]
Haze
(
1
mm
)
[
%
]
.
11. The multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 , wherein the second propylene random copolymer (P2) has a higher comonomer content and a higher amount of fraction soluble in cold xylene (XCS) than the first propylene random copolymer (P1).
12. A method comprising producing moulded articles or packaging articles with a multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 .
13. Moulded articles comprising the multimodal random heterophasic polypropylene composition (m-Raheco) according to claim 1 .