Propylene-ethylene copolymer compositions suitable for hot fill packaging of foodstuffs
Propylene-ethylene copolymer compositions and production methods are provided. The copolymer compositions can be particularly advantageous for use in hot fill packaging of foodstuffs. The propylene-ethylene copolymers can be produced using a Ziegler-Natta catalyst and an alkoxysilane electron donor. The compositions can have propylene as a primary monomer with an ethylene content ranging from 2.0 to 6.0 percent by weight with a xylene soluble content of less than 7.0 percent by weight.
1. A propylene-ethylene copolymer comprising:
propylene as a primary monomer;
an ethylene content (ET) of from 2.0% to 5% by weight;
a melt flow rate greater than 45 g/10 min and less than 100 g/10 min;
a xylene soluble fraction (XS) of from 2.0% to 7.0% by weight; and
a xylene soluble fraction to ethylene content ratio (XS/ET) of less than or equal to 1.51.
2. The propylene-ethylene copolymer of claim 1 , wherein the ethylene content is from 3.0% to 4.2% by weight.
3. The propylene-ethylene copolymer of claim 1 , wherein the ratio XS/ET is from 0.90 to 1.50.
4. The propylene-ethylene copolymer of claim 1 , wherein the ratio XS/ET is less than 1.30.
5. The propylene-ethylene copolymer of claim 1 , wherein the ratio XS/ET is less than 1.00.
6. The propylene-ethylene copolymer of claim 1 , wherein the xylene soluble fraction (XS) and the ethylene content (ET) are below a line defined by equation XS=2.1e 0.297(ET) .
7. The propylene-ethylene copolymer of claim 1 , wherein the xylene soluble fraction (XS) and the ethylene content (ET) are above a line defined by equation XS=1.4e 0.297(ET) .
8. The propylene-ethylene copolymer of claim 1 , wherein the propylene-ethylene copolymer is formed using a Ziegler-Natta catalyst and a dicyclopentyldimethoxysilane (DCPDMS) based donor.
9. The propylene-ethylene copolymer of claim 1 , wherein the propylene-ethylene copolymer is formed using a Ziegler-Natta catalyst and a n-propyltrimethoxysilane (NPTMS) based donor.
10. A polymer composition containing the propylene-ethylene copolymer of in claim 1 , wherein the propylene-ethylene copolymer is present in the polymer composition in an amount greater than about 70% by weight.
11. The polymer composition of claim 10 , further comprising a clarifying agent.
12. The polymer composition of claim 11 , wherein the clarifying agent comprises a dibenzyl sorbitol.
13. The polymer composition of claim 11 , wherein the clarifying agent comprises a nonitol.
14. The polymer composition of claim 11 , wherein the polymer composition displays a haze at 40 mil of less than about 15% and wherein after thermal aging for 24 hours at 55° C., the haze decreases by no more than about 15%.
15. An injection molded article comprising the propylene-ethylene copolymer of claim 1 .
16. The propylene-ethylene copolymer of claim 1 having a molecular weight distribution (Mw/Mn) of greater than about 3.5.
17. A hot fill packaging container comprising the propylene-ethylene copolymer of claim 1 .
18. The hot fill packaging container of claim 17 , wherein the hot fill packaging container has been formed through at least one of injection molding, blow molding, or thermoforming.