Composition suitable for thermoformable sheets and articles made therefrom
Thermoformable sheet having a thickness of at least 300 micrometers comprising a blend of: (A) from 5 to 20% by weight of a propylene-ethylene copolymer having substantially isotactic propylene sequences, the propylene-ethylene copolymer having a melt flow rate from 4 to 30 g/10 min and comprising at least 70% by weight units derived from propylene and from about 10 to 20% by weight units derived from ethylene; and (B) from 80 to 95% by weight of a polypropylene having a melt flow rate of from 2 to 8 grams/10 minutes, wherein the melt flow rate of the blend is from 2 to 7 grams/10 minutes and wherein the blend exhibits: (1) room temperature Charpy toughness of at least 15 KJ/m 2 , (2) flexural modulus of at least 1000 MPa, (3) 0 0 Charpy toughness of at least 2 KJ/m 2 , and (4) a value for haze of less than 40%.
1. A thermoformable sheet having a thickness of at least 300 μm, the thermoformable sheet comprising a blend of:
(A) from 10 to 15% by weight of a propylene-ethylene copolymer having substantially isotactic propylene sequences having an isotactic triad (mm) measured by 13 C NMR of greater than 0.85 and comprising:
(1) at least 70% by weight units derived from propylene and from about 10 to 16% by weight units derived from ethylene;
(2) the propylene-ethylene copolymer having a melt flow rate from 4 to 30 grams/10 minutes and a heat of fusion from 1 to 50 Joules/gram; and
(B) from 80 to about 95% by weight of a high crystallinity polypropylene homopolymer or high crystallinity propylene-based copolymer having up to 1% by weight of units derived from an α-olefin comonomer, having a melt flow rate of from 2 to 8 grams/10 minutes and xylene solubles less than 2% by weight,
wherein, the melt flow rate of the blend is from 2 to 7 grams/10 minutes and the blend exhibits:
(1) room temperature (23° C.) Charpy toughness of at least 9 KJ/m 2 ;
(2) flexural modulus of at least 1300 MPa;
(3) 0° Charpy toughness of at least 2 KJ/m 2 ; and
(4) a value for haze of less than 40%.
2. The thermoformable sheet of claim 1 , wherein the blend has a melt flow rate of from 3 to 5 grams/10 minutes and the propylene-ethylene copolymer (A) has a melt flow rate of from 5 to 25 grams/10 minutes.
3. The thermoformable sheet of claim 1 , wherein the propylene-ethylene copolymer (A) has a melt flow rate of from 6 to 20 grams/10 minutes.
4. The thermoformable sheet of claim 1 , wherein the propylene-ethylene copolymer (A) has a melt flow rate of from 7 to 12 grams/10 minutes.
5. The thermoformable sheet of claim 1 , wherein the blend exhibits:
(1) room temperature (23° C.) Charpy toughness of at least 9 KJ/m 2 ;
(2) flexural modulus of at least 1330 MPa by ISO 178;
(3) 0° Charpy toughness of at least 2 KJ/m 2 ; and
(4) a value for haze of less than 38%.
6. The thermoformable sheet of claim 1 , wherein the blend exhibits:
(1) room temperature (23° C.) Charpy toughness of at least 20 KJ/m 2 ;
(2) flexural modulus of at least 1350 MPa; and
(3) 0° Charpy toughness of at least 2.5 KJ/m 2 .
7. The thermoformable sheet of claim 1 , wherein the blend exhibits a value for haze of less than 37%.
8. The thermoformable sheet of claim 1 , wherein the blend exhibits a flexural modulus of at least 1330 MPa.
9. The thermoformable sheet according to claim 1 , wherein the Component (A) propylene-ethylene copolymer exhibits a skewness index greater than −1.2.
10. The thermoformable sheet of claim 9 , wherein the Component (A) propylene-ethylene copolymer is exhibits an Upper Temperature Quartile Range of greater than 4.0° C.
11. The thermoformable sheet of claim 10 , wherein the Component (A) propylene-ethylene copolymer has a molecular weight distribution (Mw/Mn) of less than 3.5.
12. The thermoformable sheet according to claim 1 , wherein the Component (A) propylene-ethylene copolymer exhibits a molecular weight distribution (Mw/Mn) of less than 3.5.
13. The thermoformable sheet of claim 1 , wherein the high crystallinity polypropylene homopolymer or propylene-based copolymer has a crystallinity of at least 70%.
14. A thermoformed article made from the thermoformable sheet of claim 1 .
15. The thermoformed article of claim 14 comprising a container or tray.
16. The thermoformed container or tray of claim 15 , wherein the container or tray is for containing food.
17. The thermoformed article of claim 14 , wherein the Component (A) propylene-ethylene copolymer exhibits a molecular weight distribution (Mw/Mn) of less than 3.5.
18. The thermoformed article of claim 14 , wherein the article comprises a food container and a wall of the container exhibits a value of haze of less than 38%.
19. The thermoformed article of claim 14 , wherein the article comprises a food container and a wall of the container exhibits a value of haze of less than 37%.
20. The thermoformed article of claim 14 , wherein the article comprises a meat tray and a wall of the meat tray exhibits a value of haze of less than 36%.
21. The thermoformed article of claim 14 , wherein the article exhibits low stress whitening behavior.
22. The thermoformed article of claim 14 , wherein the article comprises a tray or container exhibiting a value of haze of less than 20% measured according to ASTM D 1003.