Combination comprising two propylene-based polymers and compositions comprising the same
A combination comprises two propylene-based polymers which can provide flexibility in adjusting shrinkage rate of components comprising such combination.
1 . A combination comprising a first propylene-based polymer and a second propylene-based polymer, wherein the shrinkage rate of the first propylene-based polymer is higher than the shrinkage rate of the second propylene-based polymer by at least 15%, based on the shrinkage rate of the second propylene-based polymer;
wherein the first propylene-based polymer and the second propylene-based polymer are each an impact copolymer (ICP);
wherein the first propylene-based polymer is a first ICP that comprises a first polypropylene homopolymer and about 8 to about 25 wt % of a first propylene copolymer, based on a weight of the first ICP, the first propylene copolymer comprising about 25 wt % to about 60 wt % ethylene and/or C 4 to C 10 α-olefin derived units and the remainder propylene-derived units based on the weight of the first propylene copolymer; and
wherein the second propylene-based polymer is a second ICP that comprises a second polypropylene homopolymer and about 12 to about 40 wt % of a second propylene copolymer, based on a weight of the second ICP, the second propylene copolymer comprising about 30 to about 55 wt % ethylene and/or C 4 to C 10 α-olefin derived units and the remainder propylene-derived units based on the weight of the second propylene copolymer; and
wherein a difference in notched Izod impact strength between the first propylene-based polymer and the second propylene-based polymer is more than 20% based on the lower notched Izod impact strength.
2 . The combination according to claim 1 , wherein the shrinkage rate of the first propylene-based polymer is higher than the shrinkage rate of the second propylene-based polymer by at least 20% based on the shrinkage rate of the second propylene-based polymer.
3 . The combination according to claim 1 , wherein a difference in flexural modulus between the first propylene-based polymer and the second propylene-based polymer is no more than 20%, based on the lower flexural modulus.
4 . The combination according to claim 3 , wherein the first and the second propylene-based polymers further satisfy at least one of the following: (i) a difference in melt flow rate of the first propylene-based polymer and the second propylene-based polymer is no more than 20%, based on the lower melt flow rate; (ii) a difference in tensile strength at yield between the first propylene-based polymer and the second propylene-based polymer is no more than 20%, based on the lower tensile strength at yield; and (iii) a difference in tensile stress at yield between the first propylene-based polymer and the second propylene-based polymer is no more than 20%, based on the lower tensile stress at yield.
5 . The combination according to claim 1 , wherein the first and the second propylene-based polymers satisfy at least one of the following: (i) the difference in the notched Izod impact strength between the first propylene-based polymer and the second propylene-based polymer is more than 30%, based on the lower notched Izod impact strength; and (ii) a difference in flexural modulus between the first propylene-based polymer and the second propylene-based polymer is more than 20%, based on the lower flexural modulus.
6 . The combination according to claim 5 , wherein the first and the second propylene-based polymers further satisfy at least one of the following: (i) a difference in melt flow rate of the first propylene-based polymer and the second propylene-based polymer is more than 20%, based on the lower melt flow rate; (ii) a difference in tensile strength at yield between the first propylene-based polymer and the second propylene-based polymer is more than 20%, based on the lower tensile strength at yield; and (iii) a difference in tensile stress at yield between the first propylene-based polymer and the second propylene-based polymer is more than 20% based on the lower tensile stress at yield.
7 . The combination according to claim 1 , wherein the second propylene copolymer is an ethylene-propylene copolymer present in an amount of about 15 wt % to about 22 wt %, based on the weight of second ICP.
8 . The combination according to claim 7 , wherein the ethylene-propylene copolymer comprises about 30 wt % to about 45 wt % ethylene-derived units, based on the weight of the ethylene-propylene copolymer.
9 . The combination according to claim 1 , wherein a weight ratio of the first propylene-based polymer to the second propylene-based polymer ranges from about 10:90 to about 90:10.
10 . A composition comprising the combination according to claim 1 .
11 . The composition according to claim 10 , further comprising:
at least one component selected from the group consisting of polyolefin plastomers, polyolefin elastomer and filler.
12 . The composition according to claim 11 , wherein a total content of the first propylene-based polymer and the second propylene-based polymer in the composition ranges from about 45 wt % to about 80 wt %, based on the weight of the composition.
13 . A component comprising the composition according to claim 10 .
14 . A process for making a component, comprising the steps of:
(a) setting a target shrinkage rate;
(b) preparing a component comprising the composition according to claim 10 ; and
(c) adjusting a weight ratio of the first propylene-based polymer to the second propylene-based polymer to obtain the target shrinkage rate.
15 . The process according to claim 14 , wherein step (c) comprises increasing the weight ratio of the first propylene-based polymer to the second propylene-based polymer when the shrinkage rate of the component in step (b) is lower than the target shrinkage rate.
16 . The process according to claim 14 , wherein step (c) comprises decreasing the weight ratio of the first propylene-based polymer to the second propylene-based polymer when the shrinkage rate of the component in step (b) is higher than the target shrinkage rate.
17 . A propylene-based impact copolymer (ICP) comprising a polypropylene homopolymer and within a range of about 15 wt % to about 22 wt % of a propylene copolymer based on the weight of the ICP, wherein the propylene copolymer is an ethylene-propylene copolymer comprising about 30 wt % to about 45 wt % ethylene-derived units and the remainder propylene-derived units, based on the weight of the propylene copolymer; and wherein the ICP has a shrinkage rate of less than 1.4%.
18 . The ICP according to claim 17 , wherein the ICP has at least one of the following properties: (i) a melt flow rate (MFR) (230° C./2.16 kg, ASTM D1238) of about 45 g/10 min to about 55 g/10 min, (ii) an MFR of the polypropylene homopolymer of about 100 g/10 min to about 130 g/10 min, and (iii) an intrinsic viscosity of the propylene copolymer of about 1.8 dL/g to about 4 dL/g.
19 . The ICP according to claim 18 , wherein the ICP further comprises a filler in an amount of about 0.2 wt % to about 1 wt %, based on the weight of ICP.
20 . The ICP according to claim 17 , wherein the ethylene-propylene copolymer comprises about 40 wt % to about 45 wt % ethylene-derived units and the remainder propylene-derived units, based on the weight of the propylene copolymer.