Polymer composition for blow moulding
A polyethylene composition is disclosed which comprises from 45 to 55 wt % of an ethylene polymer (A) having a density of at least 968 kg/m 3 , and from 55 to 45 wt % of an ethylene polymer (B) having a density of 920 to 955 kg/m 3 , wherein the composition has a density of 952 to 961 kg/m 3 , a high load melt index HLMI of 18-28 g/10 min, a ratio of HLMI/ML of 80-150, and a melt elastic modulus G′ (G″=3000) of 1200-1600 Pa, where HLMI and ML 2 are measured according to ISO1133 at a temperature of 190° C. under loads of 21.6 kg and 2.16 kg respectively.
1. Polyethylene composition comprising from 45 to 55 wt % of an ethylene polymer (A) having a density of at least 968 kg/m 3 , and from 55 to 45 wt % of an ethylene polymer (B) having a density of 920 to 955 kg/m 3 , wherein the composition has a density of 952 to 961 kg/m 3 , a high load melt index HLMI of 18-28 g/10 min, a ratio of HLMI/MI 2 of 80-150, and a melt elastic modulus G′(G″=3000) of 1200-1600 Pa, where HLMI and MI 2 are measured according to ISO1133 at a temperature of 190° C. under loads of 21.6 kg and 2.16 kg respectively.
2. Polyethylene composition according to claim 1 , which has an HLMI of from 18 to 26.
3. Polyethylene composition according to claim 1 , which has an HLMI of from 19 to 25.
4. Polyethylene composition according to claim 1 , wherein the ratio HLMI/MI 2 is 85-140.
5. Polyethylene composition according to claim 1 , wherein the ratio HLMI/MI 2 is 85-130.
6. Polyethylene composition according to claim 1 , wherein the melt flow index MI 2 is between 0.1 g/10 min and 0.5 g/10 min.
7. Polyethylene composition according to claim 1 , wherein the melt flow index MI 2 is between 0.15 g/10 min and 0.45 g/10 min.
8. Polyethylene composition according to claim 1 , wherein the melt flow index MI 2 is between 0.2 g/10 min and 0.3 g/10 min.
9. Polyethylene composition according to claim 1 , which has a melt elastic modulus G′(G″=3000) of from 1250 to 1550 Pa.
10. Polyethylene composition according to claim 1 , which has a melt elastic modulus G′(G″=3000) is from 1300 to 1500 Pa.
11. Polyethylene composition according to claim 1 , which has a density of from 954 to 960 kg/m 3 .
12. Polyethylene composition according to claim 1 , which has a density of from 955 to 959 kg/m 3 .
13. Polyethylene composition according to claim 1 , which has a die swell ratio (DSR) as a function of shear rate (SR) satisfying the relationship DSR≧C.(SR) n where C=0.94 and n=0.094, when measured on a capillary rheometer using a Length/Diameter (L/D)=15/1 mm die at 190° C. over shear rates between 20 and 700 s −1 .
14. Polyethylene composition according to claim 1 , which has a die swell ratio equal to or greater than 1.44, when measured on a capillary rheometer using a Length/Diameter (L/D)=15/1 mm die at 190° C. at a shear rate of 100 s −1 .
15. Polyethylene composition according to claim 1 , which has a density between 954 to 959 kg/m 3 and an HLMI between 19 and 25 g/10 min, and comprises from 47 to 53 wt % of an ethylene polymer (A) having a density of between 970 and 974 kg/m 3 , and from 47 to 53 wt % of an ethylene polymer (B) having a density of between 940 and 950 kg/m 3 , the ratio of (A):(B) also being from 47:53 to 53:47.
16. Polyethylene composition according to claim 1 , which is in the form of a blow moulded article.
17. Polyethylene composition according to claim 1 , which is in the form of a blow moulded container.