EXTRUDED SOLAR POWER BACK PANEL AND MANUFACTURING METHOD THEREOF

Abstract

An extruded solar power back panel: an inner, middle, and outer layer arranged from the inside to the outside sequentially with a mass ratio of 10-40:40-80:10-40. Total thickness of the extruded solar power back panel is 0.1-0.6 mm. Highly rigid polypropylene added to inner layer ensures the bonding force between back panel and adhesive film, and improves inter-layer bonding force between back panel and polypropylene material in middle layer. Polyethylene, or a co-polymer thereof, added to the middle and outer layers, achieves excellent adhesion to polyethylene in inner layer, further improving inter-layer bonding force and low temperature thermal shock resistance of back panel. Added grafting material improves uniformity and inter-layer bonding force of product, increases the surface tension of back panel after corona treatment, and increases bonding force between back panel and silica gel used for sealing frame of solar cell.

Claims

1. An extruded solar power back panel, comprising an inner layer, a middle layer, and an outer layer arranged from the inside to the outside sequentially, wherein the mass ratio of the inner layer to the middle layer to the outer layer is 10-40:40-80:10-40; and the total thickness of the extruded solar power back panel is 0.1-0.6 mm; wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00018 polyethylene 15-85 parts polypropylene 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and copolymers thereof, its density is 0.860-0.940 g/cm.sup.3, its DSC melting point is 50-135 C., and its melt flow rate is 0.1-40 g/10 min (2.16 kg, 190 C.); the polypropylene is one or a mixture of several selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, and polypropylene block copolymer, its DSC melting point is 110-168 C., and its melt flow rate is 0.1-20 g/10 min (2.16 kg, 230 C.); the filler is one or more selected from the group consisting of glass fiber, carbon fiber, mica powder, talc powder, calcium carbonate, kaolin, wollastonite, and titanium dioxide, and the filler is a filler pre-treated by a silane coupling agent; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, and light stabilizers; the middle layer comprises the following constituents in parts by mass: TABLE-US-00019 polypropylene 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the polypropylene is one or a mixture of several selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, and polypropylene block copolymer; the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra high-density polyethylene, and copolymers thereof; the filler is one or more selected from the group consisting of glass fiber, carbon fiber, mica powder, talc powder, calcium carbonate, kaolin, wollastonite, and titanium dioxide, and the filler is a filler pre-treated by a silane coupling agent; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, and light stabilizers; the outer layer comprises the following constituents in parts by mass: TABLE-US-00020 polypropylene 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the polypropylene is one or a mixture of two selected from the group consisting of polypropylene homopolymer and polypropylene block copolymer; the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra high-density polyethylene, and copolymers thereof; the filler is one or more selected from the group consisting of glass fiber, carbon fiber, mica powder, talc powder, calcium carbonate, kaolin, wollastonite, and titanium dioxide, and the filler is a filler pre-treated by a silane coupling agent; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, and light stabilizers.

2. The extruded solar power back panel according to claim 1, wherein the silane coupling agent is one or more selected from the group consisting of vinyl trimethoxysilane, vinyl triethoxysilane, isobutyl triethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane and 3-glycidyl aminopropyl trimethoxysilane, vinyl tris(-methoxyethoxy) silane, -methacryloyloxypropyl trimethoxy silane, -mercapto-propyl triethoxysilane, N-(-amino ethyl)--aminopropylmethyl dimethoxysilane, N-(-amino ethyl)--aminopropyl triethoxysilane, N-(-amino ethyl)--amino propyl trimethoxysilane, -aminopropyl methyl diethoxysilane, diethylamino methyl triethoxysilane, anilino methyl triethoxysilane, dichloro methyl triethoxysilane, bis(-triethoxysilylpropyl) tetrasulfide, phenyl trimethoxy silane, phenyl triethoxysilane, and methyl triethoxysilane.

3. The extruded solar power back panel according to claim 1, wherein the antioxidant is one or more selected from the group consisting of bis(3,5-tert-butyl-4-hydroxy phenyl) thioether, 2,6-tert-butyl-4-methyl phenol, 2,8-di-tert-butyl-4-methyl phenol, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], tert-butyl p-hydroxyanisole, 2,6-di-tert-butylated hydroxy toluene, tert-butylhydroquinone, 2,6-di-tert-butyl phenol, 2,2-thio bis(4-methyl-6-tert-butyl phenol), 4,4-thiobis(6-tert-butyl m-cresol), N,N-di-s-butyl p-phenylenediamine, s-butyl p-phenylenediamine, 4,4-methylene bis(2,6-di-tert-butyl phenol), 2,2-methylene bis(4-methyl-6-tert-butyl phenol), didodecyl thiodipropionate, dilauryl thiodipropionate, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-p-cresol, 3,5-di-tert-butyl-4-hydroxy benzyl diethyl phosphonate, 4-[(4,6-dioctylthio-1,3,5-triazine-2-yl)amino]-2,6-di-tert-butyl phenol, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxy benzyl)benzene.

4. The extruded solar power back panel according to claim 1, wherein the UV absorbent is one or more selected from the group consisting of phenyl salicylate, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2,4-dihydroxy benzophenone, 2-hydroxy-4-methoxy benzophenone, 2-hydroxy-4-n-octoxyl benzophenone, resorcinol mono-benzoate, phenyl salicylate, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chloro benzotriazole, 2-(2-hydroxy-3,5-di-tert-phenyl)-5-chloro benzotriazole, 2-(2-hydroxy-3,5-di-tert-pentyl phenyl) benzotriazole, 2-(2-hydroxy-4-benzoyloxy phenyl)-5-chloro-2H-benzotriazole, 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyl phenol, and 2-(4,6-diphenyl-1,3,5-triazine-2)-5-n-hexyloxy phenol.

5. The extruded solar power back panel according to claim 1, wherein the light stabilizer is one or more selected from the group consisting of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, tris(1,2,2,6,6,-pentamethyl piperidinyl) phosphite, hexamethylphosphoramide, 4-benzoyloxy-2,2,6,6,-tetramethyl piperidine, bis(3,5-di-tert-butyl-4-hydroxy benzyl monoethyl phosphonate) nickel, bis(1,2,2,6,6-pentamethyl piperidinol) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyl ethanol) succinate, poly{([6-[(1,1,3,3-tetramethylbutyl) amino]]-1,3,5-triazine-2,4-[(2,2,6,6,-tetramethyl piperidinyl)]}amide, poly[6-[(1,1,3,3-tetramethylbutyl)amine]-1,3,5-triazine-2,4-diyl](2,2,6,6-tetramethyl) piperidine, 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and bis (1-octoxyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

6. A manufacturing method for the extruded solar power back panel according to claim 1, wherein the method comprises the following steps: adding materials of the inner layer, the middle layer, and the outer layer, at a ratio according to claim 1, into a screw A, a screw B, and a screw C, respectively, of a three-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

7. An extruded solar power back panel, comprising an inner layer and an outer layer arranged from the inside to the outside sequentially, wherein the mass ratio of the inner layer to the outer layer is 10-40:10-80; and the total thickness of the extruded solar power back panel is 0.1-0.6 mm; wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00021 polyethylene 15-85 parts polypropylene 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and copolymers thereof, its density is 0.860-0.940 g/cm.sup.3, its DSC melting point is 50-135 C., and its melt flow rate is 0.1-40 g/10 min (2.16 kg, 190 C.); the polypropylene is one or a mixture of several selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, and polypropylene block copolymer, its DSC melting point is 110-168 C., and its melt flow rate is 0.1-20 g/10 min (2.16 kg, 230 C.); the filler is one or more selected from the group consisting of glass fiber, carbon fiber, mica powder, talc powder, calcium carbonate, kaolin, wollastonite, and titanium dioxide, and the filler is a filler pre-treated by a silane coupling agent; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, and light stabilizers; the outer layer comprises the following constituents in parts by mass: TABLE-US-00022 polypropylene 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the polypropylene is one or a mixture of several selected from the group consisting of polypropylene homopolymer, polypropylene random copolymer, and polypropylene block copolymer; the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra high-density polyethylene, and copolymers thereof; the filler is one or more selected from the group consisting of glass fiber, carbon fiber, mica powder, talc powder, calcium carbonate, kaolin, wollastonite, and titanium dioxide, and the filler is a filler pre-treated by a silane coupling agent; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, and light stabilizers.

8. The extruded solar power back panel according to claim 7, wherein the polypropylene in the outer layer is one or a mixture of two selected from the group consisting of polypropylene homopolymer and polypropylene block copolymer.

9. A manufacturing method for the extruded solar power back panel according to claim 7, wherein the method comprises the following steps: adding materials of the inner layer and the outer layer, at a ratio according to claim 7, into a screw A and a screw B, respectively, of a two-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

10. An extruded solar power back panel, comprising an inner layer, a middle layer, and an outer layer arranged from the inside to the outside sequentially, wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00023 constituent A 15-85 parts polypropylene 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent A is a polyethylene graft, or the constituent A is a mixture of polyethylene and a polyethylene graft; the middle layer comprises the following constituents in parts by mass: TABLE-US-00024 polypropylene 75-99 parts constituent B 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent B is a polyethylene graft, or the constituent B is a mixture of polyethylene and a polyethylene graft; the outer layer comprises the following constituents in parts by mass: TABLE-US-00025 polypropylene 75-99 parts constituent C 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent C is a polyethylene graft, or the constituent C is a mixture of polyethylene and a polyethylene graft.

11. The extruded solar power back panel according to claim 10, wherein the inner layer, the middle layer, and the outer layer have the same or different polyethylene, which is one or more selected from the group consisting of polyethylene and polyethylene grafts, respectively; and the polyethylene graft is one or more selected from the group consisting of maleic anhydride grafted polyethylene, acrylic acid grafted polyethylene, and silane grafted polyethylene.

12. The extruded solar power back panel according to claim 10, wherein the polyethylene is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra high-density polyethylene, and copolymers thereof; the filler is an inorganic filler and/or an organic filler; and the additive is one or more selected from the group consisting of antioxidants, UV absorbents, light stabilizers, heat stabilizers, and silane.

13. The extruded solar power back panel according to claim 12, wherein the filler is pretreated, and the pretreatment method comprises aluminum coating, silicon coating, titanate pretreatment, and silane coupling agent pretreatment.

14. The extruded solar power back panel according to claim 10, wherein the mass ratio of the inner layer to the middle layer to the outer layer is 5-70:20-80:5-60.

15. The extruded solar power back panel according to claim 10, wherein the total thickness of the extruded solar power back panel is 0.1-0.6 mm.

16. The extruded solar power back panel according to claim 10, wherein polyethylene in the constituent A of the inner layer is one or a mixture of several selected from the group consisting of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and copolymers thereof, its density is 0.860-0.940 g/cm.sup.3, its DSC melting point is 50-135 C., and its melt flow rate is 0.1-40 g/10 min (2.16 kg, 190 C.); for polypropylene in the inner layer, the middle layer, and the outer layer, the DSC melting point is 110-175 C., and the melt flow rate is 0.1-20 g/10 min (2.16 kg, 230 C.).

17. The extruded solar power back panel according to claim 10, wherein the inner layer, the middle layer, and the outer layer have the same or different polyethylene grafts, which are one or more selected from the group consisting of maleic anhydride grafted polyethylene, acrylic acid grafted polyethylene, and silane grafted polyethylene, respectively.

18. A manufacturing method for the extruded solar power back panel according to claim 10, wherein the method comprises the following steps: adding materials of the inner layer, the middle layer, and the outer layer, at a ratio according to claim 10, into a screw A, a screw B, and a screw C, respectively, of a three-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

19. An extruded solar power back panel, comprising an inner layer and an outer layer arranged from the inside to the outside sequentially, wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00026 constituent D 15-85 parts polypropylene 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent D is a polyethylene graft, or the constituent D is a mixture of polyethylene and a polyethylene graft; the outer layer comprises the following constituents in parts by mass: TABLE-US-00027 polypropylene 75-99 parts constituent E 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent E is a polyethylene graft, or the constituent E is a mixture of polyethylene and a polyethylene graft.

20. A manufacturing method for the extruded solar power back panel according to claim 19, wherein the method comprises the following steps: adding materials of the inner layer and the outer layer, at a ratio according to claim 19, into a screw A and a screw B, respectively, of a two-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

21. An extruded solar power back panel, comprising an inner layer, a middle layer, and an outer layer arranged from the inside to the outside sequentially, wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00028 polyethylene 15-85 parts constituent F 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent F is a polypropylene graft, or the constituent F is a mixture of polypropylene and a polypropylene graft; the middle layer comprises the following constituents in parts by mass: TABLE-US-00029 constituent G 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent G is a polypropylene graft, or the constituent G is a mixture of polypropylene and a polypropylene graft; the outer layer comprises the following constituents in parts by mass: TABLE-US-00030 constituent H 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent H is a polypropylene graft, or the constituent H is a mixture of polypropylene and a polypropylene graft.

22. A manufacturing method for the extruded solar power back panel according to claim 21, wherein the method comprises the following steps: adding materials of the inner layer, the middle layer, and the outer layer, at a ratio according to claim 21, into a screw A, a screw B, and a screw C, respectively, of a three-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

23. An extruded solar power back panel, comprising an inner layer and an outer layer arranged from the inside to the outside sequentially, wherein the inner layer comprises the following constituents in parts by mass: TABLE-US-00031 polyethylene 15-85 parts constituent J 15-85 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent J is a polypropylene graft, or the constituent J is a mixture of polypropylene and a polypropylene graft; the outer layer comprises the following constituents in parts by mass: TABLE-US-00032 constituent K 75-99 parts polyethylene 1-25 parts filler 0.5-20 parts additive 0.1-5 parts; the constituent K is a polypropylene graft, or the constituent K is a mixture of polypropylene and a polypropylene graft.

24. A manufacturing method for the extruded solar power back panel according to claim 23, wherein the method comprises the following steps: adding materials of the inner layer and the outer layer, at a ratio according to claim 23, into a screw A and a screw B, respectively, of a two-layer sheet co-extrusion unit, simultaneously melting and extruding the materials at the screw extruder, and obtaining the extruded solar power back panel through casting, cooling, pulling, and rolling.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

[0093] The present invention will be further described below with reference to embodiments:

Embodiment I

[0094] An extruded solar power back panel has a 3-layer structure of an inner layer, a middle layer, and an outer layer;

[0095] (1) The inner layer structure: add 10 parts of titanium dioxide R960 (DuPont, USA) and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 (Danyang Silicone Material Industry Co., Ltd.) into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 67 parts of low-density polyethylene LD100BW (Beijing Yanshan Petrochemical, its density is 0.923 g/cm.sup.3, its DSC melting point is 110 C., and its melt flow rate is 1.8 g/10 min at 190 C./2.16 kg), 33 parts of polypropylene copolymer 1300 (Beijing Yanshan Petrochemical, its DSC melting point is 160 C., and its melt flow rate is 1.5 g/10 min at 230 C./2.16 kg), 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate] (Beijing Additive Institute, KY1010), 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone (Beijing Additive Institute, GW531), and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Beijing Additive Institute, GW480); and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0096] (2) The middle layer structure: add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 94 parts of polypropylene block copolymer K8303 (Beijing Yanshan Petrochemical, its DSC melting point is 163 C., and its melt flow rate is 2 g/10 min at 230 C./2.16 kg), 6 parts of low-density polyethylene LD100BW, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw B of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0097] (3) The outer layer structure: add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 96 parts of polypropylene copolymer 1300, 4 parts of low-density polyethylene LD100BW, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw C of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0098] (4) Simultaneously melt and extrude the three materials for the inner layer, the middle layer, and the outer layer at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the three layers inside a distributor at a ratio of 30/40/30, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product S through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm; see Table 1 for detection results.

Embodiment II

[0099] An extruded solar power back panel has a 2-layer structure of an inner layer and an outer layer;

[0100] (1) The inner layer structure: add 10 parts of titanium dioxide R960, 10 parts of talc powder (Shunxin Mineral Product Processing Factory of Lingshou County) and 0.3 parts of a silane coupling agent, 3-glycidoxypropyltrimethoxy silane KH560 (Danyang Silicone Material Industry Co., Ltd.) into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 34 parts of linear low-density polyethylene LLDPE7042 (Sinopec Yangzi Petrochemical Co., Ltd., its density is 0.918 g/cm.sup.3, its DSC melting point is 121 C., and its melt flow rate is 2 g/10 min at 230 C./2.16 kg), 33 parts of polypropylene random copolymer R370Y (Korean SK Group, its DSC melting point is 164 C., and its melt flow rate is 18 g/10 min at 230 C./2.16 kg), 33 parts of polypropylene block copolymer K8303, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0101] (2) The outer layer structure: add 10 parts of titanium dioxide R960, 10 parts of talc powder, and 0.3 parts of a silane coupling agent, 3-glycidoxypropyltrimethoxy silane KH560 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 97 parts of polypropylene block copolymer K8303, 3 parts of linear low-density polyethylene LLDPE7042, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw B of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0102] (3) Simultaneously melt and extrude the two materials for the inner layer and the outer layer at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the two layers inside a distributor at a ratio of 40/60, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product S2 through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm; see Table 1 for detection results.

Embodiment III

[0103] An extruded solar power back panel has a 3-layer structure of an inner layer, a middle layer, and an outer layer;

[0104] (1) The inner layer structure: add 10 parts of titanium dioxide R960, 10 parts of talc powder, 10 parts of sericite powder GA5 (Chuzhou Gerui Mining Co., Ltd.) and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 67 parts of low-density polyethylene LD100BW, 33 parts of polypropylene block copolymer K8303, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3, 5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0105] (2) The middle layer structure: add 10 parts of titanium dioxide R960, 10 parts of talc powder, 10 parts of sericite powder GA5, and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 26 parts of polypropylene block copolymer K8303, 28 parts of polypropylene random copolymer R370Y, 38 parts of polypropylene copolymer 1300, 8 parts of low-density polyethylene LD100BW, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw B of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0106] (3) The outer layer structure: add 10 parts of titanium dioxide R960, 10 parts of talc powder, 10 parts of sericite powder GA5, and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 38 parts of polypropylene copolymer 1300, 58 parts of polypropylene block copolymer K8303, 4 parts of low-density polyethylene LD100BW, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw C of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0107] (4) Simultaneously melt and extrude the three materials for the inner layer, the middle layer, and the outer layer at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the three layers inside a distributor at a ratio of 20/50/30, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product S3 through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm; see Table 1 for detection results.

Embodiment IV

[0108] An extruded solar power back panel has a 3-layer structure of an inner layer, a middle layer, and an outer layer;

[0109] (1) The inner layer structure: add 10 parts of titanium dioxide R960 and 3 parts of an inorganic oxide, Al.sub.2O.sub.3SiO.sub.2, into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain titanium dioxide pretreated with aluminum-silicon coating; subsequently, mix homogeneously the above pretreated titanium dioxide, 5 parts of an organic filler, polyethylene terephthalate, 64 parts of maleic anhydride grafted polyethylene, 36 parts of polypropylene random copolymer R370Y, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0110] (2) The middle layer structure: add 10 parts of titanium dioxide R960 and 3 parts of an inorganic oxide, Al.sub.2O.sub.3SiO.sub.2, into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain titanium dioxide pretreated with aluminum-silicon coating; subsequently, mix homogeneously the above pretreated titanium dioxide, 5 parts of an organic filler, polyethylene terephthalate, 20 parts of maleic anhydride grafted polyethylene, 80 parts of polypropylene block copolymer K8303, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0111] (3) The outer layer structure: add 10 parts of titanium dioxide R960 and 3 parts of an inorganic oxide, Al.sub.2O.sub.3SiO.sub.2, into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain titanium dioxide pretreated with aluminum-silicon coating; subsequently, mix homogeneously the above pretreated titanium dioxide, 5 parts of an organic filler, polyethylene terephthalate, 20 parts of maleic anhydride grafted polyethylene, 50 parts of polypropylene block copolymer K8303, 43 parts of polypropylene copolymer 1300, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0112] (4) Simultaneously melt and extrude the three materials for the inner layer, the middle layer, and the outer layer at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the three layers inside a distributor at a ratio of 20/50/30, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product S4 through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm; see Table 2 for detection results.

Embodiment V

[0113] Other constituents and quantities thereof, as well as the preparation process are all the same as those in Embodiment IV. The difference is that the inner layer material selects 80 parts of maleic anhydride grafted polyethylene and 80 parts of maleic anhydride grafted polypropylene; the middle layer material selects 20 parts of maleic anhydride grafted polyethylene and 80 parts of maleic anhydride grafted polypropylene; and the outer layer material selects 20 parts of maleic anhydride grafted polyethylene and 90 parts of maleic anhydride grafted polypropylene; the finished product is marked as S5.

Embodiment VI

[0114] Other constituents and quantities thereof, as well as the preparation process are all the same as those in Embodiment IV. The difference is that the inner layer material selects 70 parts of low-density polyethylene LD100BW and 83 parts of maleic anhydride grafted polypropylene; the middle layer material selects 13 parts of low-density polyethylene LD100BW, 10 parts of high-density polyethylene 5000S, and 70 parts of maleic anhydride grafted polypropylene; and the outer layer material selects 20 parts of high-density polyethylene 5000S and 90 parts of maleic anhydride grafted polypropylene; the finished product is marked as S6.

Embodiment VII

[0115] In this embodiment, a back panel material having a 2-layer structure of an inner layer and an outer layer is prepared, wherein all constituents and quantities thereof are the same as the raw materials and quantities thereof used by the inner layer and the outer layer in Embodiment IV. The difference is that the melting and co-extrusion process uses a 2-layer sheet co-extrusion unit. The finished product is marked as S7.

Embodiment VIII

[0116] In this embodiment, a back panel material having a 2-layer structure of an inner layer and an outer layer is prepared, wherein all constituents and quantities thereof are the same as the raw materials and quantities thereof used by the inner layer and the outer layer in Embodiment V. The difference is that the melting and co-extrusion process uses a 2-layer sheet co-extrusion unit. The finished product is marked as S8.

Embodiment IX

[0117] In this embodiment, a back panel material having a 2-layer structure of an inner layer and an outer layer is prepared, wherein all constituents and quantities thereof are the same as the raw materials and quantities thereof used by the inner layer and the outer layer in Embodiment VI. The difference is that the melting and co-extrusion process uses a 2-layer sheet co-extrusion unit. The finished product is marked as S9.

Comparative Example I

[0118] (1) Add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent KH560 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm; subsequently, add 100 parts of an EVA resin, 0.2 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.1 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate to mix homogeneously; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 60 mm and an aspect ratio of 33;

[0119] (2) Add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent KH560 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm; subsequently, mix homogeneously the treated titanium dioxide, 50 parts of polypropylene block copolymer K8303, and 50 parts of high-density polyethylene 5000S, and add them into a twin-screw extruder for granulation by melting and extrusion; add 100 parts of the above prepared finished product into the fast stirring machine, add 0.2 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.1 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate to mix homogeneously; and add the homogeneously mixed materials into a screw B of the three-layer sheet co-extrusion unit, the screw has a diameter of 90 mm and an aspect ratio of 33;

[0120] (3) Add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent KH560 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm; subsequently, add 100 parts of an EVA resin, 0.2 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.1 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate to mix homogeneously; and add the homogeneously mixed materials into a screw C of the three-layer sheet co-extrusion unit, the screw has a diameter of 60 mm and an aspect ratio of 33;

[0121] (4) Simultaneously melt and extrude the above three materials at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the three layers inside a distributor at a ratio of 20/50/30, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product S3 through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm, i.e., B1; see Table 1 for detection results.

Comparative Example II

[0122] (1) Mix homogeneously polypropylene resin, an organic UV absorbent, 5% 2-hydroxy-4-n-methoxyl benzophenone, and an inorganic antioxidant with a high-speed mixer, extrude to granulate with a twin-screw extruder, and obtain a modified polyolefin resin;

[0123] (2) Mix homogeneously 85% POE resin, 5% photoinitiator, 5% photosensitizer, and 5% anti-bisphenol A phosphite solution with a high-speed mixer, dry the solvent at 50 C. in an oven, and obtain a modified POE mixture;

[0124] (3) Coat an anti-hydrolysis coating having a thickness of 5 m on the surface of a PET film, and obtain an anti-hydrolysis PET film;

[0125] (4) Melt and extrude the modified polypropylene resin obtained in the step 1 and the modified POE mixture obtained in the step 2 through an extruder to obtain a modified polyolefin film and a modified POE film, which are attached, respectively, to two sides of the anti-hydrolysis PET film in the step 3 that has been subjected to corona surface treatment to obtain a composite film having a 3-layer structure, which is marked as B2; see Table 1 for detection results.

Comparative Example III

[0126] (1) The inner layer structure: add 10 parts of titanium dioxide R960 and 0.2 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 20 parts of low-density polyethylene LD100BW, 80 parts of linear low-density polyethylene LLDPE7042, 100 parts of polypropylene random copolymer R370Y, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw A of a three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0127] (2) The middle layer structure: add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 100 parts of polypropylene copolymer 1300, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw B of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0128] (3) The outer layer structure: add 10 parts of titanium dioxide R960 and 0.3 parts of a silane coupling agent, 3-aminopropyl triethoxysilane KH550 into a fast stirring machine, and stir for 30 min at a rotational speed of 600 rpm to obtain a filler pretreated with the silane coupling agent; subsequently, mix homogeneously the above filler pretreated with the silane coupling agent, 100 parts of polypropylene block copolymer K8303, 0.1 parts of an antioxidant, pentaerythritol tetra[-(3,5-di-tert-butyl-4-hydroxy phenyl) propionate], 0.2 parts of a UV absorbent, 2-hydroxy-4-n-octoxyl benzophenone, and 0.2 parts of a light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and add the homogeneously mixed materials into a screw C of the three-layer sheet co-extrusion unit, the screw has a diameter of 75 mm and an aspect ratio of 33;

[0129] (4) Simultaneously melt and extrude the three materials for the inner layer, the middle layer, and the outer layer at the screw extruder, control the temperature between 180 and 240 C., the rotational speed at 100 rpm, and the residence time of the materials in the screw between 2 and 4 min, distribute the materials of the three layers inside a distributor at a ratio of 30/40/30, then enter a T-shaped die, the die width being 1200 mm, and obtain a finished product B3 through processes like cooling, pulling, and rolling, the temperature of three-roll cooling water being 60-70 C. and the pulling velocity being 3-4 m/min. The product has a thickness of 0.33 mm and a width of 1000 mm; see Table 1 for detection results.

[0130] See Table 2 for some detection results of the back panel products obtained in Embodiment IV through Embodiment IX and the products obtained in Comparative Examples I through III.

[0131] Subsequently, performance testing is conducted on the above embodiments and comparative examples. The specific methods are as follows:

[0132] 1. Shrinkage Test

[0133] The test was conducted according to the testing method prescribed in GB/T 13541, Testing Method for Plastic Films in Electric Applications.

[0134] 2. Water Vapor Permeation Test

[0135] The test was conducted according to the testing method prescribed in GB/T 21529, Testing Method for Water Vapor Permeation of Plastic Films and Thin Sheets.

[0136] 3. Elastic Modulus Test

[0137] The test was conducted according to the testing method prescribed in GB/T1040.3-2006, Measurement of Plastic Tensile Performance, Part 3: Experimental Conditions for Films and Thin Sheets.

[0138] 4. Saturated Water Absorption Test

[0139] The test was conducted according to the testing method prescribed in GB/T1034, Testing Method for Water Absorption of Plastics.

[0140] 5. Interlayer Peeling Strength Test

[0141] The interlayer peeling strength between an inner layer and a middle layer was tested, and the test was conducted according to the testing method prescribed in GB/T2792, Testing Method for 1800 Peeling Strength of Pressure Sensitive Adhesive Tape.

[0142] 6. Test on Impact Resistance at a Low Temperature

[0143] The test was conducted according to the testing methods prescribed in GB/T2423.1-2008, Environmental Test of Electric and Electronic Products, Part 2: Test Methods, Experiment A: low temperature, and GB/T1843-2008, Measurement of Impact Strength of Plastic Cantilever Beam, and the test temperature was 40 C. Prepared notch impact specimens of a cantilever beam were placed in a low temperature box with the preset temperature, and when thermal equilibrium was reached, the specimens were taken out one by one for a quick impact test on a cantilever beam impact tester.

[0144] 7. Test of Ageing by Humidity and Heat

[0145] The ageing by humidity and heat was conducted according to the testing method of ageing by moisture and heat prescribed in IEC 61215: 2005, and the experimental conditions were: a temperature of 85 C., a relative humidity of 85%, and a testing time of 1500 hours.

[0146] 8. Test of Bonding Strength with EVA Before and after Accelerated Ageing Test at High Temperature (PCT)

[0147] The PCT test was conducted according to JESD 22-102A, and the experimental conditions were: relative humidity 100%, 121 C., 2 atm, and 48 hours. The bonding strength between a back panel and EVA was tested according to the testing methods prescribed in GB/T2792, Testing Method for 1800 Peeling Strength of Pressure Sensitive Adhesive Tape.

[0148] 9. Volume Resistivity Test

[0149] The test was conducted according to the testing method prescribed in GB/T1410, Volume Resistivity and Surface Resistivity of Solid Insulating Materials.

[0150] 10. Breaking Strength and Elongation at Break Test

[0151] The test was conducted according to ASTM D638, Standard Testing Method for Plastic Tensile Strength. Samples were taken randomly from different parts of back panels with 5 specimens from each back panel for testing of longitudinal breaking strength and elongation at break, which were used to analyze the uniformity of the back panels.

[0152] 11. Surface Tension of Samples Before and after Corona Treatment

[0153] Surface tension of the back panels after corona treatment was tested according to ASTM D7490-2013, Standard Measurement Method for Measurement of Surface Tension for Solids including Coating, Paint and Substrates.

TABLE-US-00016 TABLE 1 Results of performance testing of solar power back panels in all embodiments and comparative examples Solar power back panel S1 S2 S3 B1 B2 B3 Shrinkage, % Longitudinal 0.8 0.7 0.6 1.0 1.5 0.8 (150 C., 30 min) Lateral 0.5 0.3 0.2 0.5 0.8 1.0 Water vapor permeation, g .Math. m.sup.2 .Math. d.sup.1 0.31 0.34 0.32 0.34 1.6 0.33 (23 C., 85% RH) Elastic modulus (MPa) 1050 983 1100 820 2000 1000 Bonding strength with EVA, N/cm * * * * 95 * Saturated water absorption, % 0.13 0.12 0.11 0.14 0.82 0.14 (boiling water, 30 min) Interlayer peeling force, N/cm 24 21 23 22 5.0 10 Impact resistance at a low temperature, KJ/m.sup.2 32 36 34 3.1 1.5 4.3 Ageing Appearance No obvious No obvious No obvious No obvious Yellow, No obvious by discoloration, discoloration, discoloration, discoloration, stratified, discoloration, humidity no no no no embrittlement no and heat stratification, stratification, stratification, stratification, stratification, (85 C., no no no no no 85% RH, embrittlement embrittlement embrittlement embrittlement embrittlement 1500 h) Elongation Longitudinal 97 95 99 70 75 at Lateral 96 97 95 66 67 break, % PCT Appearance No obvious No obvious No obvious Yellow, Yellow, No obvious ageing discoloration, discoloration, discoloration, stratified, stratified, discoloration, no no no embrittlement embrittlement no stratification, stratification, stratification, stratification, no no no no embrittlement embrittlement embrittlement embrittlement Bonding strength with 58 65 62 52 EVA, N/cm Volume resistivity, * cm 5.3 * 10.sup.17 3.6 * 10.sup.17 9.8 * 10.sup.17 3.2 * 10.sup.17 8.6 * 10.sup.15 3.4 * 10.sup.17 * Note: the peeling strength was too high to pull them apart.

TABLE-US-00017 TABLE 2 Results of performance testing of solar power back panels in embodiments 4-9 and comparative examples Bonding Interlayer strength Elongation at peeling with Surface Breaking break force EVA tension Products strength (MPa) (%) (N/cm) (N/cm) (dyn/cm) S1 Specimen 1 28 Specimen 1 1334 24 * 38 Specimen 2 38 Specimen 2 999 Specimen 3 46 Specimen 3 1168 Specimen 4 35 Specimen 4 1012 Specimen 5 47 Specimen 5 970 S2 Specimen 1 45 Specimen 1 1234 21 * 35 Specimen 2 37 Specimen 2 1432 Specimen 3 26 Specimen 3 908 Specimen 4 51 Specimen 4 894 Specimen 5 43 Specimen 5 1070 S3 Specimen 1 41 Specimen 1 1213 23 * 37 Specimen 2 27 Specimen 2 1342 Specimen 3 36 Specimen 3 1098 Specimen 4 46 Specimen 4 870 Specimen 5 39 Specimen 5 1392 S4 Specimen 1 46 Specimen 1 1340 35 * 47 Specimen 2 47 Specimen 2 1365 Specimen 3 46 Specimen 3 1368 Specimen 4 46 Specimen 4 1342 Specimen 5 47 Specimen 5 1370 S5 Specimen 1 50 Specimen 1 1502 33 * 45 Specimen 2 52 Specimen 2 1498 Specimen 3 52 Specimen 3 1500 Specimen 4 51 Specimen 4 1496 Specimen 5 51 Specimen 5 1488 S6 Specimen 1 47 Specimen 1 1356 30 * 48 Specimen 2 48 Specimen 2 1349 Specimen 3 48 Specimen 3 1348 Specimen 4 47 Specimen 4 1335 Specimen 5 48 Specimen 5 1329 S7 Specimen 1 46 Specimen 1 1389 32 * 45 Specimen 2 47 Specimen 2 1398 Specimen 3 47 Specimen 3 1369 Specimen 4 46 Specimen 4 1384 Specimen 5 46 Specimen 5 1394 S8 Specimen 1 51 Specimen 1 1598 34 * 46 Specimen 2 52 Specimen 2 1584 Specimen 3 52 Specimen 3 1574 Specimen 4 52 Specimen 4 1586 Specimen 5 51 Specimen 5 1562 S9 Specimen 1 48 Specimen 1 1384 33 * 49 Specimen 2 48 Specimen 2 1387 Specimen 3 47 Specimen 3 1364 Specimen 4 47 Specimen 4 1358 Specimen 5 48 Specimen 5 1349 B1 Specimen 1 37 Specimen 1 1154 3.1 * 30 Specimen 2 42 Specimen 2 1492 Specimen 3 35 Specimen 3 1057 Specimen 4 45 Specimen 4 1500 Specimen 5 30 Specimen 5 988 B2 Specimen 1 46 Specimen 1 1587 1.5 95 29 Specimen 2 38 Specimen 2 1262 Specimen 3 40 Specimen 3 1289 Specimen 4 32 Specimen 4 965 Specimen 5 52 Specimen 5 1426 B3 Specimen 1 42 Specimen 1 1328 4.3 * 28 Specimen 2 32 Specimen 2 891 Specimen 3 47 Specimen 3 1485 Specimen 4 29 Specimen 4 956 Specimen 5 34 Specimen 5 1246 * Note: the peeling strength was too high to pull them apart.

[0154] It can be seen from Table 1 that compared with the 3-layer solar power back panel using EVA in the inner layer (Comparative Example I), the extruded solar power back panel according to the present invention has higher mechanical strength, impact strength at low temperature and better ageing resistance; compared with the solar power back panel using PET as the substrate film (Comparative Example II), the extruded solar power back panel according to the present invention has higher blocking performance, bonding strength, impact strength at low temperature and better ageing resistance, Compared with Comparative Example III, the interlayer peeling force and impact resistance at a low temperature of the solar power back panel according to the present invention have been significantly improved, indicating that the solar power back panel according to the present invention has extremely high interlayer bonding force and impact resistance at a low temperature. After the accelerated ageing test at high temperature (PCT test), the extruded solar power back panel according to the present invention still keeps good appearance and relatively high bonding strength, which extends the service life of the back panel and a solar power cell assembly using the back panel. Therefore, the solar power back panel according to the present invention has high interlayer bonding force, high bonding performance, high blocking performance, high mechanical strength, and excellent impact resistance at a low temperature.

[0155] At the same time, it can be seen from Table 2 that the values of breaking strength and elongation at break are not significantly different among samples from different parts after breaking strength and elongation at break tests were performed on samples taken from different parts of the solar power back panel products obtained in Embodiments IV through IX, while the values of breaking strength and elongation at break are significantly different among samples from different parts of the products obtained in Embodiments I through III and Comparative Examples I through III, indicating that the solar power back panel products introduced with grafted polymers have better uniformity;

[0156] The interlayer peeling force of the solar power back panel products obtained in Embodiments IV through IX is also greater than that of Embodiments I through III and Comparative Examples I through III, indicating that the introduction of the grafted materials improves the interlayer bonding performance; moreover, the bonding force with EVA film is also higher, indicating that the back panels have excellent bonding performance;

[0157] After corona treatment was performed on the products, it can be seen that the surface tension of the products obtained in Embodiments IV through IX is significantly greater than the surface tension of the solar power back panels in Embodiments I through III and Comparative Examples I through III, indicating that the introduction of the grafted materials improves the surface tension after the final corona treatment on the products and can ensure tight bonding between the back panels and the frame sealing silica gel.

[0158] The above embodiments are only preferred implementation modes of the present invention, and cannot be used to limit the scope of the present invention. Any non-substantive modifications and substitutions made by a person skilled in the art on the basis of the present invention shall be encompassed by the scope of the present invention.