Polyethylene composition for a film layer
View Patent ↗The present invention relates to a polymer composition, to the use of the polymer composition in film applications and to a film comprising the polymer composition of the invention.
1. A polymer composition comprising:
(a) a multimodal polymer of ethylene with at least two different comonomers selected from alpha-olefins having from 4 to 10 carbon atoms,
which has
a) a melt flow rate MFR 2 of 0.5 to 10 g/10 min (according to ISO 1133 at 190° C. under 2.16 kg load),
b) a melt flow ratio MFR 21 /MFR 2 of 13 to 30 (MFR 21 at 190° C. under 21.6 kg load), and
c) a molecular weight distribution MWD defined by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), determined by Gel Permeation Chromatography (GPC), of 5 or less;
wherein:
the multimodal polymer of ethylene (a) comprises at least
an ethylene polymer component (A) and
an ethylene polymer component (B),
the MFR 2 of the ethylene polymer component (A) is different from the MFR 2 of the ethylene polymer component (B); and
the alpha-olefin comonomer having from 4 to 10 carbon atoms of ethylene polymer component (A) is different from the alpha-olefin comonomer having from 4 to 10 carbon atoms of ethylene polymer component (B).
2. The polymer composition according to claim 1 , wherein the ethylene polymer component (A) has a MFR 2 of 1 to 50 g/10 min.
3. The polymer composition according to claim 1 , wherein the MFR 2 of ethylene polymer component (A) is higher than the MFR 2 of ethylene polymer component (B).
4. The polymer composition according to claim 1 , wherein the alpha-olefin comonomer of the ethylene polymer component (A) is 1-butene and the alpha-olefin comonomer of the ethylene polymer component (B) is 1-hexene.
5. The polymer composition according to claim 1 , wherein the multimodal polymer of ethylene (a) is further multimodal with respect to the comonomer content.
6. The polymer composition according to claim 1 , wherein the ratio of [the amount (mol %) of alpha-olefin comonomer having from 4 to 10 carbon atoms comonomer present in ethylene polymer component (A)] to [the amount (mol %) of at least two alpha-olefin comonomers having from 4 to 10 carbon atoms of the final multimodal polymer of ethylene (a)] is of 0.2 to 0.6.
7. The polymer composition according to claim 1 , wherein the amount (mol %) of alpha-olefin comonomer having from 4 to 10 carbon atoms present in the ethylene polymer component (A) is of 0.03 to 5.0 mol %.
8. The polymer composition according to claim 1 , wherein the multimodal polymer of ethylene (a) is further multimodal with respect to density.
9. The polymer composition according to claim 1 , wherein the density of the ethylene polymer component (A) is of 925 to 950 kg/m 3 .
10. The polymer composition according to claim 1 , wherein the density of the multimodal polymer of ethylene (a) is of 910 to 935 kg/m 3 .
11. The polymer composition according to claim 1 , wherein the multimodal polymer of ethylene (a) has MFR 21 /MFR 2 of 15 to 30.
12. The polymer composition according to claim 1 , wherein the multimodal polymer of ethylene (a) is multimodal with respect to MFR, type of the comonomer, comonomer content and density.
13. The polymer composition according to claim 1 , wherein polymer composition has a the tensile modulus in machine direction (MD) of 200 to 350 MPa when determined according to ISO 527-1 and ISO 527-3 and measured from a film sample (40 μm thickness) consisting of the polymer composition.
14. The polymer composition according to claim 1 , wherein the polymer composition, has a shear thinning index SHI 2.7/210 of 1.5 to 7 when determined according to ISO 6721-1 and ISO 6721-10.
15. The polymer composition according to claim 1 , wherein the multimodal polymer of ethylene (a) is produced using a single site catalyst.
16. An article comprising the polymer composition according to claim 1 .
17. A film comprising at least one layer which comprises the polymer composition according to claim 1 .