Polymer composition for a layer of a layer element
View Patent ↗The present invention relates to a polymer composition, to a layer element, preferably to at least one layer element of a photovoltaic module, comprising the polymer composition and to an article which is preferably said at least one layer of a layer element, preferably of a layer element of a photovoltaic module.
1. A polymer composition comprising:
i) a polymer of ethylene (a) with a polar comonomer(s), wherein
the polar comonomer is selected from the group of methyl acrylate and methyl methacrylate, and wherein
the polymer of ethylene (a) optionally bears functional group(s) containing units other than said polar comonomer, and
the polymer of ethylene (a) has a melt temperature of 78° C. or more, and
ii) silane group(s) containing units (b), wherein the silane group(s) containing units (b) and the polymer of ethylene (a) are present in the polymer composition as separate components or as a blend or the silane group(s) containing units (b) are present as a comonomer of the polymer of ethylene (a) or as a compound grafted to the polymer of ethylene (a), and
wherein the polymer composition has
an MFR 2 of 13 to 70 g/10 min (according to ISO 1133 at 190° C. and at a load of 2.16 kg), and
a Shear Thinning Index, SHI 0.05/300 , of 10.0 to 35.0, when measured according to ISO 6721-1 and 6721-10.
2. The polymer composition according to claim 1 , wherein the MFR 2 of the polymer composition, is from 13 to 50 g/10 min.
3. The polymer composition according to claim 1 , wherein the polymer composition has one or two of the rheological properties a) and b):
a) Shear Thinning Index, SHI 0.05/300 , of 10.0 to 30.0, and/or
b) G″(at 5 kPa) of 2000 to 5000 kPa, when measured according to ISO 6721-1 and 6721-10.
4. The polymer composition according to claim 1 , wherein difference in Refractive Index of the polymer composition within the temperature range from 10 to 70° C. is less than 0.0340, when measured in a refractometer.
5. The polymer composition according to claim 1 , wherein the polymer composition has a Transmittance of at least 88.2% when measured in a UV/VIS/NIR spectrometer according to draft standard IEC 82/666/N.
6. The polymer composition according to claim 1 , wherein the content of polar comonomer present in the polymer of ethylene (a) is of 4.5 to 18 mol %, when measured by quantitative 1 H NMR.
7. The polymer composition according to claim 1 , wherein the polymer of ethylene (a) has a weight average molecular weight Mw of at least 70 000.
8. The polymer composition according to claim 1 , which has a Water Permeation of 20 000 or less mg-mm/(m2-day), when measured at 38° C. according to ISO 15106-3:2003.
9. The polymer composition according to claim 1 , which has 1) a Tensile modulus MD of 6 to 30 MPa, or 2) a Tensile modulus TD of 5 to 30 MPa, when measured according to.
10. The polymer composition according to claim 1 , wherein the density of the polymer of ethylene (a) is 930-957 kg/m 3 .
11. The polymer composition according to claim 1 , wherein the polymer of ethylene (a) with the polar comonomer(s) is a polymer of ethylene with methyl acrylate comonomer and optionally bears functional group(s) containing units.
12. The polymer composition according to claim 1 , wherein the polymer of ethylene (a) with the polar comonomer(s) bears silane group(s) containing units (b) as said functional groups containing units, wherein the amount of the silane group(s) containing units (b) in the polymer of ethylene (a) is from 0.01 to 1.00 mol %, when determined by quantitative 1 H NMR.
13. The polymer composition according to claim 1 , wherein the silane group(s) containing units (b) as the functional groups bearing units are present in said polymer of ethylene (a) in form of comonomer units.
14. The polymer composition according to claim 1 , wherein the silane group(s) containing comonomer unit or compound as silane group(s) containing units (b) is a hydrolysable unsaturated silane compound represented by the formula:
R 1 SiR 2 q Y 3-q (I)
wherein;
R 1 is an ethylenically unsaturated hydrocarbyl, hydrocarbyloxy or (meth)acryloxy hydrocarbyl group,
each R 2 is independently an aliphatic saturated hydrocarbyl group,
Y which may be the same or different, is a hydrolysable organic group, and
q is 0, 1 or 2.
15. The polymer composition according to claim 1 , wherein the polar polymer of ethylene (a) is a copolymer of ethylene with methyl acrylate comonomer and a hydrolysable silane group(s) containing comonomer.
16. An article comprising the polymer composition according to claim 1 .
17. The article according to claim 16 , which is a layer element, wherein said layer element comprises at least one layer comprising the polymer composition.
18. The article according to claim 16 , which is a photovoltaic module comprising at least one photovoltaic element and at least one layer element comprising at least one layer, wherein said at least one layer comprises the polymer composition.
19. A photovoltaic module comprising at least one photovoltaic element and at least one layer element which is a monolayer element comprising the polymer composition according to claim 1 , or a multilayer element comprising two or more layer(s), wherein at least one layer comprises the polymer composition according to claim 1 .
20. The photovoltaic module according to claim 19 , wherein said at least one layer element is an encapsulation monolayer element comprising the polymer composition, or an encapsulation multilayer element which comprises at least one layer comprising the polymer composition.