Polymer composition for injection moulding

1. A multimodal polyethylene composition having a base resin, the base resin comprising

(A) a first polyethylene fraction which is an ethylene homopolymer, and

(B) a second polyethylene fraction,

wherein the melt flow rate MFR 5/190° C. of the first fraction is higher than the melt flow rate MFR 5/190° C. of the second fraction; the flow rate ratio FRR 21/5 of the polyethylene composition, defined as the ratio of melt flow rate MFR 21.6/190° C. to melt flow rate MFR 5/190° C. , is within the range of 20-24; and the melt flow rate MFR 5/190° C. of the polyethylene composition is within the range of 0.5-1.1 g/10 min;

wherein the composition has a shear thinning index (SHI), defined as the ratio of viscosity at a shear stress of 2.7 kPa to viscosity at a shear stress of 210 kPa, within the range of 15-40; and

wherein the base resin has a density of from 0.945 to 0.952 g/cm 3 .

2. The polyethylene composition according to claim 1 , wherein the flow rate ratio FRR 21/5 of the polyethylene composition is 20.

3. The polyethylene composition according to claim 1 , wherein the flow rate ratio FRR 21/5 of the polyethylene composition is 24.

4. The polyethylene composition according to claim 1 , wherein the shear thinning index (SHI) of the composition is within the range of 15 to 32.

5. The polyethylene composition according to claim 1 , wherein the density of the base resin is within the range of 0.947 to 0.952 g/cm 3 .

6. The polyethylene composition according to claim 1 , wherein the density of the base resin is within the range of 0.949 to 0.952 g/cm 3 .

7. A multimodal polyethylene composition having a base resin, the base resin comprising

(A) a first polyethylene fraction which is an ethylene homopolymer,

(B) a second ethylene fraction, and

(C) a prepolymer fraction,

wherein the melt flow rate MFR 5/190° C. of the first fraction is higher than the melt flow rate MFR 5/190° C. of the second fraction; the flow rate ratio FRR 21/5 of the polyethylene composition, defined as the ratio of melt flow rate MFR 21.6/190° C. to melt flow rate MFR 5/190° C. , is within the range of 20-24; and the melt flow rate MFR 5/190° C. of the polyethylene composition is within the range of 0.5-1.1 g/10 min;

wherein the composition has a shear thinning index (SHI), defined as the ratio of viscosity at a shear stress of 2.7 kPa to viscosity at a shear stress of 210 kPa, within the range of 15-40;

wherein the base resin has a density of from 0.945 to 0.952 g/cm 3 ;

wherein the prepolymer fraction is an ethylene homopolymer present in amount of from greater than 0 wt % to 20 wt % of the base resin.

8. A multimodal polyethylene composition having a base resin, the base resin comprising

(A) a first polyethylene fraction which is an ethylene homopolymer,

(B) a second polyethylene fraction, and

(C) a prepolymer fraction,

wherein the melt flow rate MFR 5/190° C. of the first fraction is higher than the melt flow rate MFR 5/190° C. of the second fraction; the flow rate ratio FRR 21/5 of the polyethylene composition, defined as the ratio of melt flow rate MFR 21.6/190° C. to melt flow rate MFR 5/190° C. , is within the range of 20-24; and the melt flow rate MFR 5/190° C. of the polyethylene composition is within the range of 0.5-1.1 g/10 min;

wherein the composition has a shear thinning index (SHI), defined as the ratio of viscosity at a shear stress of 2.7 kPa to viscosity at a shear stress of 210 kPa, within the range of 15-32;

wherein the base resin has a density of from 0.949 to 0.952 g/cm 3 ; and

wherein the prepolymer fraction is an ethylene homopolymer present in amount of from greater than 0 wt % to 20 wt % of the base resin.