Co-extruded one-time-formed solar cell module backboard in three-layer structure

Abstract

The present invention discloses a co-extruded one-time-formed solar cell module backboard in a three-layer structure. The backboard is formed by co-extruding three layers: a middle layer located in the middle as well as an outer layer and an inner layer located at two sides of the middle layer, and has high water resisting capability, high reflective rate, good long-term aging resistance performances of hydrolysis resistance, UV resistance and heat resistance and good recoverability and environmental protection performance. Compared with the prior art, the backboard has better water resisting ability, higher reflectivity, better long-term aging resistance performances of hydrolysis resistance, UV resistance and heat resistance, better recoverability and environmental protection performance and lower cost. Compared with a backboard in a co-extruded structure in the prior art, the backboard of the present invention has better heat resistance, better dimensional stability and higher mechanical breaking strength.

Claims

1. A co-extruded one-time-formed solar cell module backboard in a three-layer structure, characterized in that: the backboard is formed by co-extruding a middle layer (3), an outer layer (1) and an inner layer (2); wherein the middle layer (3) is located in the middle and the outer layer (1) and the inner layer (2) are located at two sides of the middle layer (3); the middle layer (3) is composed of a polymer network plastic alloy obtained from a crosslinking reaction between two or more of a component A, a component B, a component C, a component D and a first functional filler in a co-extrusion process; the component A is composed of one or two of, Polystyrene (PS), Polyphenylene Sulfide (PPS), Polyphenylene Oxide (PPO), Polymethyl Methacrylate (PMMA), Polyvinyl Butyral (PVB), and Cyclic Olefin Copolymer (COC); the component B is composed of one or two of Linear Low-Density Polyethylene (LLDPE)-g-Glycidyl Methacrylate (GMA), Low-Density Polyethylene (LDPE)-g-GMA, Medium-Density Polyethylene (MDPE)-g-GMA, High-Density Polyethylene (HDPE)-g-GMA, Ultrahigh Molecular Weight Polyethylene (UHMWPE)-g-GMA, Styrene-Ethylene/Butylene-Styrene block copolymer (SEBS)-g-GMA, Homo-Polypropylene (HOPP)-g-GMA, Co-Polypropylene (COPP)-g-GMA, PS-g-GMA, PPO-g-GMA, ethylene octene copolymerized Polyolefin Elastomers (POE)-g-GMA, ethylene pentene copolymerized POE-g-GMA, Polycarbonate (PC)-g-GMA, Ethylene Propylene Diene Monomer (EPDM)-g-GMA and COC; the component C is composed of one or two of PMMA, PVB, phenoxy resin and crystalline polyester polyol; the component D is nylon polyolefin graft copolymer; and the first functional filler is selected from one or more of Al.sub.2O.sub.3, aluminium hydroxide, CaCO.sub.3, barium sulfate, diatomaceous earth, pumice powder and diamond powder; wherein the middle layer (3) comprises the following components by weight ratio: 0-99% of the component A, 0.5%-99% of the component B, 0.5%-99% of the component C, 0-99% of the component D and 0.5%-90% of the first functional filler.

2. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 1, characterized in that: the middle layer (3) comprises the following components by weight ratio: 0-90% of the component A, 0.5%-80% of the component B, 0.5%-90% of the component C, 0-50% of the component D and 0.5%-30% of the first functional filler.

3. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 1, wherein the outer layer (1) is composed of a polymer network plastic alloy obtained from a crosslinking reaction between two or more of a component E, a component F, a component G, and a second functional filler in a co-extrusion process; the component E is composed of one or two of LLDPE, LDPE, MDPE, HDPE, UHMWPE, SEBS, ethylene octene copolymerized POE, ethylene pentene copolymerized POE, PMMA, PVB and COC; the component F is composed of one or two of LLDPE-g-GMA, LDPE-g-GMA, MDPE-g-GMA, HDPE-g-GMA, UHMWPE-g-GMA, SEBS-g-GMA, ethylene octene copolymerized POE-g-GMA, ethylene pentene copolymerized POE-g-GMA, EPDM-g-GMA, LLDPE-g-Maleic Anhydride (MAH), LDPE-g-MAH, MDPE-g-MAH, HDPE-g-MAH, UHMWPE-g-MAH, SEBS-g-MAH, ethylene octene copolymerized POE-g-MAH, ethylene pentene copolymerized POE-g-MAH, EPDM-g-MAH and nylon polyolefin graft copolymer; the component G is composed of one or two of, PMMA, PVB, phenoxy resin and crystalline polyester polyol; and the second functional filler is selected from one or more of Al.sub.2O.sub.3, aluminium hydroxide, SiO.sub.2, CaCO.sub.3, carbon black, barium sulfate, diatomaceous earth, pumice powder and diamond powder.

4. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 3, wherein the outer layer (1) comprises the following components by weight ratio: 0-99% of the component E, 0.5%-99% of the component F, 0.5%-99% of the component G and 0.5%-90% of the second functional filler.

5. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 4, wherein the outer layer (1) comprises the following components by weight ratio: 0-90% of the component E, 0.5%-90% of the component F, 0.5%-90% of the component G and 1%-40% of the second functional filler.

6. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 1, wherein the inner layer (2) is composed of a polymer network plastic alloy obtained from a crosslinking reaction between two or more of a component H, a component J, a component K, and a third functional filler in a co-extrusion process; wherein the component H is composed of one or two of LLDPE, LDPE, MDPE, HDPE, UHMWPE, SEBS, ethylene octene copolymerized POE, ethylene pentene copolymerized POE, PMMA, PVB and COC; the component J is composed of one or two of LLDPE-g-GMA, LDPE-g-GMA, MDPE-g-GMA, HDPE-g-GMA, UHMWPE-g-GMA, SEBS-g-GMA, ethylene octene copolymerized POE-g-GMA, ethylene pentene copolymerized POE-g-GMA, EPDM-g-GMA, LLDPE-g-MAH, LDPE-g-MAH, MDPE-g-MAH, HDPE-g-MAH, UHMWPE-g-MAH, SEBS-g-MAH, ethylene octene copolymerized POE-g-MAH, ethylene pentene copolymerized POE-g-MAH, EPDM-g-MAH and nylon polyolefin graft copolymer; the component K is composed of one or two of PMMA, PVB, phenoxy resin and crystalline polyester polyol; and the third functional filler is selected from one or more of Al.sub.2O.sub.3, aluminium hydroxide, SiO.sub.2, CaCO.sub.3, carbon black, barium sulfate, diatomaceous earth, pumice powder and diamond powder.

7. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 6, wherein the inner layer (2) comprises the following components by weight ratio: 0-99% of the component H, 0.5%-99% of the component J, 0.5%-99% of the component K and 0.5%-90% of the third functional filler.

8. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 7, wherein the inner layer (2) comprises the following components by weight ratio: 0-90% of the component H, 0.5%-90% of the component J, 0.5%-90% of the component K and 1%-40% of the third functional filler.

9. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 1, wherein a thickness of the middle layer (3) is 0.010 mm-0.500 mm, the thickness of the outer layer (1) is 0.010 mm-0.100 mm, and the thickness of the inner layer (2) is 0.010 mm-0.100 mm.

10. The co-extruded one-time-formed solar cell module backboard in the three-layer structure of claim 1, wherein when an angle of projection of a light ray for measuring a gloss is 60 degrees, a surface gloss of the outer layer (1) is 1-99, and the surface gloss of the inner layer (2) is 1-99; and when a range of wavelength of a light ray for measuring a reflectivity is 400-1100 nm, a surface reflectivity of the inner layer (2) is 1%-99%.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a structural schematic diagram of a co-extruded one-time-formed solar cell module backboard of the present invention; and

(2) FIG. 2 is a structural schematic diagram of a solar cell module composed by the co-extruded one-time-formed solar cell module backboard of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1

(3) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production, namely, hybrid polymerized films are formed by a high-temperature co-extrusion film making process,

(4) wherein the outer layer (1) comprises raw materials (by mass percent, similarly hereinafter) of 88% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(5) the chemical formula of the outer layer (1) is: [NH(CH.sub.2).sub.11CO].sub.n; the inner layer (2) comprises raw materials of 19% of EVA, 69% of LLDPE and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(6) the chemical formula of the inner layer (2) is: (C.sub.2H.sub.4)(C.sub.4H).sub.2)+(C.sub.2H.sub.4).sub.n,

(7) wherein the chemical formula of EVA is: (C.sub.2H.sub.4)(C.sub.4H.sub.6O.sub.2).sub.y, and the chemical formula of LLDPE is: (C.sub.2H.sub.4).sub.6; and

(8) the middle layer (3) comprises raw materials of 98% of HOPP and 2% of TiO.sub.2 and is 0.250 mm in thickness,

(9) wherein the chemical formula of HOPP is: (C.sub.3H.sub.6).sub.n.

(10) The hybrid polymerized films are formed by the high-temperature co-extrusion film making process.

Embodiment 2

(11) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer,

(12) wherein the outer layer (1) comprises raw materials of 88% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(13) the chemical formula of PA12 is: [NH(CH.sub.2).sub.11CO].sub.n;

(14) the inner layer (2) comprises raw materials of 88% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(15) the middle layer (3) comprises raw materials of 98% of PA12 and 2% of TiO.sub.2 and is 0.250 mm in thickness;

(16) Hybrid polymerized films are formed by a high-temperature co-extrusion film making process.

Embodiment 3

(17) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(18) wherein the outer layer (1) comprises raw materials of 65% of HDPE-g-GMA, 23% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness, and the chemical formula of HDPE is: [CH.sub.2CH.sub.2-].sub.n;

(19) the inner layer (2) comprises raw materials of 65% of HDPE-g-GMA, 23% of PA112 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(20) the middle layer (3) comprises raw materials of 58% of HOPP, 20% of PP-g-GMA, 20% of PA12 and 2% of TiO.sub.2 and is 0.250 mm in thickness. A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(21) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time; one hybrid polymerized alloy film is formed at each layer, while every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 4

(22) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(23) wherein the outer layer (1) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(24) the inner layer (2) comprises raw materials of 20% of LLDPE, 48% of POE, 10% of POE-g-GMA, 10% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(25) the middle layer (3) comprises raw materials of 58% of HOPP, 20% of PP-g-GMA, 20% of PA12 and 2% of TiO.sub.2 and is 0.250 mm in thickness. A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(26) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 5

(27) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(28) wherein the outer layer (1) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness,

(29) wherein the chemical formula of HDPE is: [CH.sub.2CH.sub.2-].sub.n;

(30) the inner layer (2) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(31) the middle layer (3) comprises raw materials of 70% of HDPE-g-GMA, 24% of PA12 and 6% of TiO.sub.2 and is 0.250 mm in thickness. A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(32) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymer alloy film.

Embodiment 6

(33) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(34) wherein the outer layer (1) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(35) the inner layer (2) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(36) the middle layer (3) comprises raw materials of 60% of HOPP/COPP-g-GMA, 16% of PA12, 4% of TiO.sub.2 and 20% of HDPE-g-GMA and is 0.250 mm in thickness.

(37) A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(38) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 7

(39) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(40) wherein the outer layer (1) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(41) the inner layer (2) comprises raw materials of 64% of HDPE-g-GMA, 24% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(42) the middle layer (3) comprises raw materials of 60% of HOPP, 26% of COC (Cyclic Olefin Copolymer) and 4% of TiO.sub.2 and is 0.250 mm in thickness, and the chemical formula of COC is:

(43) ##STR00001##

(44) A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(45) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 8

(46) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(47) wherein the outer layer (1) comprises raw materials of 43% of nylon polyolefin graft copolymer Apolhya, 30% of HDPE-g-GMA, 15% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(48) the inner layer (2) comprises raw materials of 43% of nylon polyolefin graft copolymer Apolhya, 30% of HDPE-g-GMA, 15% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(49) the middle layer (3) comprises raw materials of 46% of HOPP, 30% of HOPP/COPP-g-GMA, 10% of nylon polyolefin graft copolymer Apolhya, 10% of PA12 and 4% of TiO.sub.2 and is 0.250 mm in thickness. A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(50) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 9

(51) FIG. 1 is a structural schematic diagram of a solar cell module backboard (4) in a three-layer structure. The solar cell module backboard (4) comprises a middle layer (3) which is located in the middle as well as an outer layer (1) and an outer layer 2 which are located at the two sides of the middle layer, and is made by three-layer co-extrusion one-time continuous production,

(52) wherein the outer layer (1) comprises raw materials of 43% of nylon polyolefin graft copolymer Apolhya, 30% of HDPE-g-GMA, 15% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness;

(53) the inner layer (2) comprises raw materials of 43% of nylon polyolefin graft copolymer Apolhya, 30% of HDPE-g-GMA, 15% of PA12 and 12% of TiO.sub.2 and is 0.050 mm in thickness; and

(54) the middle layer (3) comprises raw materials of 75% of HOPP/COPP-g-GMA, 21% of PA12 and 4% of TiO.sub.2 and is 0.250 mm in thickness. A crosslinking reaction is carried out on a part of raw materials by a high-temperature co-extrusion film making process, so as to form hybrid polymerized alloy films.

(55) In an actual manufacturing process, the three layers of materials are processed by the high-temperature co-extrusion film making process at one time, one hybrid polymerized alloy film is formed at each layer, and every two adjacent layers are fused, crosslinked and adhered together by the compatibility of polymers and the crosslinking reaction, so as to form an integrated polymerized alloy film.

Embodiment 10

(56) FIG. 2 is a structural schematic diagram of a solar cell module backboard (9) in a common structure type. The solar cell module backboard (9) is in a five-layer structure, which comprises a middle layer (10) which is located in the middle, a fluorine-containing film which is located at an outer layer (11), an adhesive layer (12) which is used for adhering the outer layer (11) and the middle layer (10), an inner layer 13) which is located at the side of a cell piece and an adhesive layer (14) which is used for adhering the inner layer (13) and the middle layer (10), and the five layers are adhered together by a compounding method, wherein the outer layer (11) is made of the fluorine-containing film and is 0.025 mm in thickness; the inner layer (13) is made of LLDPE and is 0.095 mm in thickness; the middle layer (10) is made of a PET film and is 0.250 mm in thickness; and the adhesive layer (12) is 0.015 mm in thickness, and the adhesive layer (14) is 0.015 mm in thickness. Assessment and test results are shown in Table 1.

(57) TABLE-US-00001 TABLE 1 Assessment and Test Results of Solar Cell Module Backboards in Embodiments 1-10 Specification Test Item Judgment Value Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Overall Thickness (mm) 350 350 350 350 350 Initial Breaking MD 30 MD = 23 MD = 55 MD = 24 MD = 21 MD = 25 Tensile Strength (MPa) TD 30 TD = 18 TD = 51 TD = 20 TD = 19 TD = 21 Breaking Tensile None MD = 18 MD = 38 MD = 20 MD = 17 MD = 20 Strength (MPa) TD = 12 TD = 35 TD = 15 TD = 15 TD = 16 after DH2000 Hours Attenuation Rate (%) None MD = 21.74 MD = 30.91 MD = 16.67 MD = 19.05 MD = 20 TD = 33.33 TD = 31.37 TD = 25 TD = 21.05 TD = 23.81 Assessment Initial Breaking MD 50 MD = 80 MD = 200 MD = 67 MD = 62 MD = 60 Tensile Rate (%) TD 50 TD = 75 TD = 168 TD = 56 TD = 53 TD = 52 Initial Breaking None MD = 58 MD = 108 MD = 58 MD = 53 MD = 51 Tensile Rate (%) TD = 54 TD = 97 TD = 46 TD = 42 TD = 41 after DH2000 Hours Attennation Rate (%) None MD = 27.5 MD = 46.00 MD = 13.43 MD = 14.52 MD = 15 TD = 28.00 TD = 42.26 TD = 17.85 TD = 20.76 TD = 21.57 Assessment Inner-Layer 80 90% 91% 92% 90.5%.sup. 90.8%.sup. Reflectivity (%) (400-1100 nm) Assessment Dimension Stability MD 1.5 MD = 1.46 MD = 1.40 MD = 0.85 MD = 1.08 .sup.MD = 0.95 (%) (150 C., 30 TD 1.5 TD = 1.40: .sup.TD = 1.20 .sup.TD = 0.70 .sup.TD = 1.02 TD = 0.92 Minutes) Assessment Water Vapor 2.5 1.03 3.5 0.75 0.8 0.9 Permeation Rate (g/m.sup.2 day) Assessment X Heat Resistance (TI) 90 90 105 105 105 125 Assessment Breakdown Voltage 15 17.6 17.2 18.7 18.2 18.5 Resistance (KV) Assessment Partial Discharge (V) 1000 1020 1112 1280 1272 1260 (PDV) (in the air) Assessment UV and Yellowing Yellowing index: 5.1 5 3 2.2 2.1 Resistance YI < 5 after 300 KWh of irradiation on the surface of the inner layer Assessment X UV and Yellowing Yellowing index: 5.2 5 3 2.0 2.1 Resistance YI < 5 after 300 KWh of irradiation on the surface of the outer layer Assessment X General Assessment X Standard of Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Embodiment 10 Testing Method 350 350 350 350 350 MD = 39 MD = 34 MD = 32 MD = 38 MD = 106 GB/T TD = 32 TD = 31 TD = 31 TD = 33 TD = 92 31034-2014 MD = 31 MD = 29 MD = 28 MD = 32 MD = 15 TD = 25 TD = 26 TD = 25 TD = 27 TD = 12 MD = 20.51 MD = 14.71 MD = 12.5 MD = 15.79 MD = 85.85 TD = 21.88 TD = 16.13 TD = 19.36 TD = 18.19 TD = 86.96 X MD = 63 MD = 61 MD = 65 MD = 67 MD = 108 GB/T TD = 53 TD = 56 TD = 58 TD = 59 TD = 100 31034-2014 MD = 50 MD = 52 MD = 53 MD = 55 MD = 13 GB/T TD = 43 TD = 45 TD = 48 TD = 49 TD = 9 31034-2014 MD = 20.64 MD = 14.75 MD = 18.46 MD = 17.91 MD = 87.96 TD = 18.87 TD = 19.64 TD = 17.24 TD = 16.95 TD = 91 X 91.2%.sup. 91.2%.sup. 91% 91.5%.sup. 85% Demands of mainstream customers MD = 0.80 MD = 0.80 MD = 0.70 MD = 0.66 MD = 1.05 GB/T .sup.TD = 0.75 .sup.TD = 0.75 .sup.TD = 0.69 .sup.TD = 0.60 TD = 0.8 31034-2014 0.92 0.92 0.80 0.81 1.8 GB/T 31034-2014 Infrared method 125 125 125 125 105 IEC60216-5 18.8 18.9 19 18.5 18 GB/T 31034-2014 1310 1310 1320 1301 1021 GB/T 31034-2014 2.1 2.2 2.5 2.2 4 ASTM E313 2.1 2.2 2.6 2.5 2 ASTM E313

(58) The embodiments 4-9 have the best comprehensive assessments. Therefore, it is concluded that the performance of the embodiments using the dynamic crosslinking technology are obviously improved, is obviously more excellent than a backboard in a same structure not using the technology and is also better than currently widely-used backboards in different structures.

(59) Notes: =optimal =excellent =good x=poor

(60) From the above embodiments, it is observed that the solar cell module backboard in the three-layer structure in the present invention has excellent performance of high heat dissipation rate, high reflective rate, high water resistance ratio, good long-term ageing resistance and the like. Compared with the prior art, the backboard has better water resisting ability, higher reflective rate, better long-term aging resistance performance of hydrolysis resistance, UV resistance and heat resistance, better recoverability and environmental protection performance and lower cost. Compared with a backboard in a structure in the prior art, which is directly formed by co-extrusion without the crosslinking reaction, the backboard of the present invention has better heat resistance, better dimensional stability and higher mechanical breaking strength after the dynamic crosslinking technology or the reactive extrusion technology is used.

(61) The above embodiments are only used for explaining the technical conceptions and characteristics of the present invention, for the purpose that those skilled in the art can understand the contents of the present invention and implement the present invention according to the contents, and the above embodiments do not limit the protection scope of the present invention. Any equivalent change or modification made according to the spiritual substance of the present invention shall be included in the protection scope of the present invention.