BACK SHEET FOR SOLAR CELL MODULE AND SOLAR CELL MODULE MADE THEREOF

1 . A back sheet for a solar cell module comprising:

(iv) a substrate comprising a silane crosslinked polyethylene composition;

(v) an adhesive layer comprising a polyurethane; and

(vi) a weather resistant layer comprising a fluoropolymer;

wherein:

the weather resistant layer (iii) has a front surface and a back surface, the front surface faces towards a light source when in use;

the adhesive layer (ii) is in contact with the substrate (i) and the front surface of the weather resistant layer (iii); and

the silane crosslinked polyethylene composition is derived from the reaction of components (a), (b), (c), (d), (e) and (f) as follows:

(g) 60 to 98.74 wt % of a polyethylene selected from the group consisting of linear low density polyethylene, high density polyethylene, low density polyethylene, and blends thereof;

(h) 0.1 to 2.5 wt % of a silane;

(i) 1 to 3 wt % of a titanium dioxide;

(j) 0.05 to 0.5 wt % of a peroxide;

(k) 0.01 to 0.05 wt % of a carboxylate of tin; and

(l) 0.1 to 33.95 wt % of at least one additive selected from the group consisting of inorganic fillers excluding titanium dioxide, anti-oxidant agents, anti-UV agents, lubricants, and mixtures thereof;

wherein the wt % is based on the total weight of the combined components.

2 . The back sheet of claim 1 , wherein the silane is selected from the group consisting of vinyltrimethoxy silane, vinyltriethoxy silane, vinyltris(2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxy silane, and mixtures thereof.

3 . The back sheet of claim 1 , wherein the peroxide is selected from the group consisting of dicumyl peroxide, benzoyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, and mixtures thereof.

4 . The back sheet of claim 1 , wherein the carboxylate of tin is selected from the group consisting of dibutyl tin dilaurate, dibutyltin laurate maleate, di-n-butyltin, stannous octoate, dibutyltin diacetate, and mixtures thereof.

5 . The back sheet of claim 1 , wherein the substrate (i) has a thickness of 100 to 500 μm, and has no hole or less than 15 holes per 100 m 2 on the surface of the substrate (i).

6 . The back sheet of claim 1 , wherein adhesive layer (ii) has a thickness of 5 to 20 μm, and the weather resistant layer (iii) has a thickness of 5 to 50 μm.

7 . The back sheet of claim 1 , wherein the inorganic fillers excluding titanium dioxide is selected from the group consisting of glass fibers, talcs, silica dioxides, micas, zinc sulfides, calcium carbonates, boron nitrides, clays, and mixtures thereof, and the weight of the inorganic fillers excluding titanium dioxide is 3 to 35 wt %, based on the total weight of the combined components.

8 . The back sheet of claim 1 , wherein the fluoropolymer is selected from homopolymers and copolymers of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, and combinations of two or more thereof.

9 . A solar cell module comprising at least one solar cell having a front surface and a back surface, a back encapsulant layer, and the back sheet of claim 1 , wherein the back encapsulant layer is in contact with the back surface of the solar cell and the substrate (i) of the back sheet; and the front surface of solar cell faces towards a light source when in use.

10 . The solar cell module of claim 9 , wherein the back encapsulant layer comprises a polymeric material selected from ethylene vinyl acetate, polyolefin, and blends thereof.

11 . A method for manufacturing a back sheet for a solar cell module comprising:

(7) providing a layer comprising a fluoropolymer as a weather resistant layer, which has a front surface and a back surface;

(8) applying a layer comprising a polyurethane to the front surface of the weather resistant layer to obtain an adhesive layer;

(9) providing components (a), (b), (c), (d), (e), and (f) as follows:

(a) 60 to 98.74 wt % of a polyethylene selected from the group consisting of linear low density polyethylene, high density polyethylene, low density polyethylene, and blends thereof;

(b) 0.1- to 2.5 wt % of a silane;

(c) 1 to 3 wt % of a titanium dioxide;

(d) 0.05 to 0.5 wt % of a peroxide;

(e) 0.01 to 0.05 wt % of a carboxylate of tin; and

(f) 0.1 to 33.95 wt % of at least one additive selected from the group consisting of glass fibers, talcs, silica dioxides, micas, zinc sulfides, calcium carbonates, boron nitrides, clays, anti-oxidant agents, anti-UV agents, lubricants, and mixtures thereof;

wherein the wt % is based on the total weight of the combined components;

(10) blending the components (a), (b), (c), (d), (e) and (f) at a temperature of 180 to 230° C. to obtain a blend;

(11) casting the blend of Step (4) to obtain a sheet comprising a silane crosslinked polyethylene composition; and

(12) laminating the sheet comprising a silane crosslinked polyethylene composition on top of the adhesive layer to obtain the back sheet.