A polyolefin uv-resistant backsheet and a method of making the same

Abstract

The present application relates to H01L, more particularly, the present application relates to a kind of polyolefin UV-resistant backboard and its preparation method.It includes: inner layer: by polyolefin adhesive layer and polyolefin structural layer co-extrusion preparation is obtained;Outer layer: including air layer and aluminized layer, the aluminized layer one side connects air layer, the other side connects polyolefin structural layer.The present application provides a kind of backboard, can be used in photovoltaic module, provide high water vapor transmission resistance and boiling resistance performance simultaneously, the present application utilizes inner layer co-extrusion polyolefin material also can keep high thickness retention simultaneously, also with EVA adhesive film has high adhesion and interlayer adhesion, and added plastic particle and filler etc. also can and UV-resistant agent jointly play the role of heat conduction, UV-resistant, can improve the usability under temperature change or humid heat condition.

Description

Technical Field

[0001] This invention relates to H01L, and more specifically, to a polyolefin UV-resistant backsheet and its preparation method. Background Technology

[0002] Photovoltaic modules are mainly composed of cover plates, encapsulant films, solar cells, encapsulant films, and backsheets. Among them, the backsheet, as the encapsulation structure of photovoltaic modules, has a significant impact on the lifespan of the cells.

[0003] CN107275429A discloses an extruded solar backsheet, in which a rigid polypropylene is added to the inner layer, which not only ensures the adhesion between the backsheet and the adhesive film, but also improves the interlayer adhesion between the backsheet and the intermediate polypropylene material, resulting in better sealing performance.

[0004] However, polypropylene has a higher melting temperature than polyethylene, and the film cannot melt during hot pressing, making it difficult to form a stable bond with the film. At the same time, the temperature resistance and water vapor permeability resistance of the resulting polyolefin backing also need to be further improved. Summary of the Invention

[0005] To address the aforementioned problems, a first aspect of the present invention provides a polyolefin UV-resistant backsheet, the backsheet comprising:

[0006] Inner layer: prepared by co-extrusion of a polyolefin adhesive layer and a polyolefin structural layer;

[0007] Outer layer: includes an air layer and an aluminum plating layer, wherein the aluminum plating layer is connected to the air layer on one side and to the polyolefin structural layer on the other side.

[0008] [Inner layer]

[0009] Polyolefin adhesive layer

[0010] In one embodiment, the raw materials for preparing the polyolefin adhesive layer include, by weight, 100 parts of polyethylene, 10-50 parts of plastic particles, 1-10 parts of UV resistant agent, and 1-10 parts of antioxidant.

[0011] In one embodiment, the plastic particles are selected from at least one of polyamide, polycarbonate, polyethylene sulfide, polyethyl ether ketone, polyether ether ketone, and polyimide. Polyether ether ketone is preferred.

[0012] Examples of polyetheretherketone (PEEK) include PEEK 021FC30 from Changchun Jida University (density: 1.45 g / cm³). 3 Melt index at 400℃ / 5kg: 22±2g / 10min), PEEK 021GF30 (density: 1.51g / cm³) 3Melt flow index at 400℃ / 5kg: 25±2g / 10min), PEEK 021CF20 (density: 1.4g / cm³) 3 Melt flow index at 400℃ / 5kg: 22±2g / 10min), PEEK 021G (density: 1.32g / cm³). 3 Melt flow index at 400℃ / 5kg: 20 to 24 g / 10min), PEEK021CF30 (density: 1.4 g / cm³) 3 The melt flow index of the polyetheretherketone (PEEK) at 400℃ / 5kg is 23 to 27 g / 10min. The density test method for PEEK is ISO 1183, and the melt flow index test method is ISO 1133-97. Preferably, the melt flow index of the PEEK at 400℃ / 5kg is 20 to 30 g / 10min.

[0013] In the process of bonding the backing sheet and EVA, fusible polyethylene is generally used to improve the adhesion between the backing sheet and EVA. However, the inventors also found that the fusible polyethylene layer is not conducive to maintaining the thickness of the backing sheet. Therefore, polypropylene is generally added to improve the thickness stability. However, the adhesion between polypropylene and EVA layer is poor. This invention is different. By constructing a two-layer co-extruded A-layer structure, infusible plastic particles are set in the polyethylene matrix of the bonding layer in contact with the EVA film to promote the maintenance of the thickness of the bonding layer during the interaction with the film. A structural layer with higher hardness is set on the side of the bonding layer away from the film to further avoid the influence of the bonding layer PE on the thickness and maintain the thickness stability.

[0014] In one embodiment, the polyethylene in the polyolefin adhesive layer is selected from at least one of low-density polyethylene, medium-density polyethylene, and linear low-density polyethylene, preferably medium-density polyethylene or linear low-density polyethylene, with a weight ratio of 1:1 to 2.

[0015] As an example of medium-density polyethylene, DowDuPont's MDPE FO A-6548 BK (density: 0.945 g / cm³) can be cited. 3 Melt flow index at 190℃ / 2.16kg: 0.7g / 10min), MDPE FO A-8864 BK (density: 0.941g / cm³). 3 The melt flow index (MFI) of the medium-density polyethylene at 190℃ / 2.16kg is 0.7g / 10min. The density test method for polyethylene is ASTM D792, and the melt flow index test method is ASTM D1238. Preferably, the melt flow index of the medium-density polyethylene at 190℃ / 2.16kg is 0.6–0.8g / 10min.

[0016] Examples of linear low-density polyethylene include DowDuPont's LLDPE 4105 (density: 0.930 g / cm³). 3 Melt flow index at 190℃ / 2.16kg: 4.0g / 10min), LLDPE 4157 (density: 0.920g / cm³). 3 Melt flow index at 190℃ / 2.16kg: 3.0g / 10min), LLDPE 2535 (density: 0.919g / cm³). 3 Melt flow index (190℃ / 2.16kg: 6g / 10min) and LLDPE IP 20 (density: 0.926g / cm³) are also mentioned. 3 Melt index at 190℃ / 2.16kg: 20g / 10min). Preferably, the melt index of the linear low-density polyethylene at 190℃ / 2.16kg is 3-6g / 10min.

[0017] In one embodiment, the thickness of the polyolefin adhesive layer is 10-50 μm, and the particle size of the plastic particles is 60-70% of the thickness of the polyolefin adhesive layer. Furthermore, the inventors have discovered that when plastic particles are added, the structural differences between the plastic particles and polyethylene make it difficult to uniformly form the adhesive layer structure during co-extrusion. However, the inventors have found that by adding polyetheretherketone (PEEK) as plastic particles, its alternating ether and ketone bond structure promotes suitable fluidity in low-density polyethylene and medium-density polyethylene with appropriate melt indices, thereby promoting film extrusion molding and structural uniformity. Moreover, by controlling the particle size of the plastic particles relative to the extruded layer, the polyolefin adhesive layer obtained in this invention can uniformly encapsulate the particles, allowing the polyethylene to contact the plastic particles during melting and EVA film entanglement, reducing direct contact between the film and plastic particles during hot pressing, and minimizing the reduction in thickness caused by penetration into the film.

[0018] Examples of UV resistant agents include, but are not limited to, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, phenyl benzoate, 2-(2-hydroxy-3,5-ditert-pentylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(4,6-diphenyl-1,3,5-triazine-2)-5-n-hexyloxyphenol.

[0019] Examples of antioxidants include, but are not limited to, 2,6-tert-butyl-4-methylphenol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester, 2,6-di-tert-butylphenol, triphenyl phosphite, 2,6-di-tert-butyl-p-cresol, 3,5-di-tert-butyl-4-hydroxybenzyl diethylphosphonate, pentaerythritol tetrakis[β-(3,5-di-tert-butylphenyl)propionate], and tris(2,4-di-tert-butylphenyl)phosphite.

[0020] Polyolefin structural layer

[0021] In one embodiment, the raw materials for preparing the polyolefin structural layer, by weight, include 100 parts polypropylene, 10-20 parts polyethylene, 10-20 parts ethylene copolymer, 1-10 parts UV resistant agent, and 1-10 parts antioxidant. The thickness of the polyolefin structural layer is 150-300 μm.

[0022] In one embodiment, the polypropylene is selected from random copolymer polypropylene and / or block copolymer polypropylene.

[0023] As an example of block polypropylene, one can cite JPC Iran's PP EP-YS30RE (density: 0.9 g / cm³). 3 Melt flow index of 1.3 g / 10 min at 230℃ / 2.16 kg), PP EP-S31HP (density: 0.9 g / cm³). 3 Melt flow index of 1.3 g / 10 min at 230℃ / 2.16 kg), PP EP-Q30M (density: 0.9 g / cm³). 3 Melt flow index of 0.8 g / 10 min at 230℃ / 2.16 kg), PP EP-D60R (density: 0.9 g / cm³). 3 The melt flow index (MFI) of the block polypropylene at 230℃ / 2.16kg is 0.4 g / 10min. The density test method for the block polypropylene is ISO 1183, and the melt flow index test method is ISO 1133-97. Preferably, the melt flow index of the block polypropylene at 230℃ / 2.16kg is 0.9 to 1.5 g / 10min.

[0024] In one embodiment, the polyethylene in the polyolefin structural layer is selected from high-density polyethylene.

[0025] Examples of high-density polyethylene include DowDuPont's HDPE DGDA-6944 NT (density: 0.965 g / cm³). 3 Melt flow index (190℃ / 2.16kg: 8g / 10min) and HDPE DMDA-8910 NT 7 (density: 0.943g / cm³) are also mentioned. 3Melt flow index: 10g / 10min (190℃ / 2.16kg), HDPE DGDP-6097NT 7 (density: 0.950g / cm³). 3 Melt index at 190℃ / 2.16kg: 11g / 10min). Preferably, the melt index of the high-density polyethylene at 190℃ / 2.16kg is 8 to 11g / 10min.

[0026] In one embodiment, the polyolefin structural layer further includes 10-20 parts of filler, wherein the filler is selected from one or more of carbon nanotubes, nano-magnesium oxide, titanium dioxide, and nano-alumina. Preferably, carbon nanotubes and nano-magnesium oxide are used in a weight ratio of 1:2-3. Carbon nanotubes are one-dimensional quantum materials with radial dimensions on the nanometer scale and axial dimensions on the micrometer scale. They can be self-made or purchased. When purchased, LUCAN CP 1002M (radial dimension 8-15 nm, axial dimension 10-70 μm) from LG Chem is available. This invention does not specifically limit the nano-magnesium oxide; it can be purchased from Beijing Deco Island Gold Technology Co., Ltd., specifically nano-magnesium oxide DK-MgO-001 (particle size 30-50 nm).

[0027] Furthermore, the inventors discovered that the incompatibility between plastic particles and PE creates micropores, leading to problems such as moisture penetration, UV exposure, or increased shrinkage. The presence of plastic particles also affects the adhesion performance with EVA. This invention addresses these issues by adding a polyolefin air layer and aluminum foil to isolate the effects of air and water vapor. Additionally, it incorporates nano-carbon nanotubes and high-hardness nano-zinc oxide in the structural layer. During co-extrusion, these nanotubes partially enter the micropores of the adhesive layer at the interface, reducing shrinkage and improving adhesion to the EVA film when interacting with it.

[0028] In one embodiment, the ethylene copolymer includes binary ethylene copolymers, such as POE, maleic anhydride grafts of homopolymer polyethylene, and silane grafts of homopolymer polyethylene. Examples of POE include DowDuPont's POE 8540 (melt index at 190°C / 2.16 kg: 1.0 g / 10 min), POE 8450 (melt index at 190°C / 2.16 kg: 3.0 g / 10 min), and POE 8480 (melt index at 190°C / 2.16 kg: 1 g / 10 min). The melt index test method for POE is ASTM D1238. Preferably, the melt index of the POE at 190°C / 2.16 kg is 1–3 g / 10 min.

[0029] In one embodiment, the ethylene copolymer further includes terpolymers, such as CO-ethylene-n-butyl acrylate terpolymer and ethylene-propylene-butadiene terpolymer. Examples of ethylene-propylene-nonconjugated diene terpolymers include DowDuPont's EPMD 4640 (ethylene content: 55wt%, ethylene-norbornene content: 5wt%, Mooney viscosity at ML 1+4, 125°C: 40MU), EPMD 4725P (ethylene content: 70wt%, ethylene-norbornene content: 5wt%, Mooney viscosity at ML 1+4, 125°C: 25MU), EPMD 3722P (ethylene content: 70.5wt%, ethylene-norbornene content: 0.5wt%, Mooney viscosity at ML 1+4, 125°C: 20MU), EPMD 3720P (ethylene content: 69wt%, ethylene-norbornene content: 0.5wt%, Mooney viscosity at ML 1+4, 125°C: 20MU), and EPMD 3722P. EL (ethylene content: 70 wt%, ethylene-norbornene content: 0.5 wt%, Mooney viscosity at ML 1+4, 125°C: 20 MU). The ethylene content test method for EPDM is ASTM D3900, the ethylene-norbornene test method is ASTM D6047, and the Mooney viscosity at ML 1+4, 125°C is ASTM D1646. Preferably, the ethylene-propylene-non-conjugated diene terpolymer has an ethylene content of 65–75 wt%, an ethylene-norbornene content of 0.1–1 wt%, and a Mooney viscosity at ML 1+4, 125°C of 15–25 MU.

[0030] In one embodiment, the weight ratio of the binary ethylene copolymer to the terethylene copolymer is 1:0.3 to 0.5. The inventors discovered that further addition of terethylene and binary ethylene copolymers to the structural layer not only further promotes entanglement with the adhesive layer but also enhances the interaction with plastic particles, further reducing micropores and improving adhesion. Furthermore, the inventors found that utilizing the formation of the dispersed phase of the copolymer within the continuous phases of polyethylene and polypropylene further promotes the retention of thickness during hot pressing of the film, resulting in an inner layer film material with low shrinkage and high adhesion.

[0031] This invention does not limit the specific method of inner layer co-extrusion molding, but can be co-extrusion casting molding, co-extrusion stretch molding, co-extrusion blow molding, etc., which are well known in the art.

[0032] [Outer layer]

[0033] In one embodiment, the thickness of the air layer is 10–50 μm. This invention does not specifically limit the air layer; examples include PET air layers, polyolefin air layers, and fluorocarbon air layers. As an example of a polyolefin air layer, its raw materials, by weight, include 100 parts polypropylene, 10–20 parts polyethylene, 1–10 parts UV resistant agent, 1–10 parts antioxidant, and 5–15 parts titanium dioxide. It may also include other additives, such as free radical scavengers and free radical quenchers. The specific types and amounts of additives are not specifically limited; additives well-known in the art can be used. This invention does not specifically limit the polypropylene and polyethylene in the air layer; the polypropylene can be block polypropylene, atactic polypropylene, etc., and the polyethylene can be high-density polyethylene, high-density linear polyethylene, etc.

[0034] In one embodiment, the thickness of the aluminum plating layer is 10-40 nm; the side of the air layer near the aluminum plating layer is electroplated.

[0035] The second aspect of the present invention provides a method for preparing the aforementioned polyolefin UV-resistant backsheet, comprising: preparing an inner layer and an outer layer by adhesive bonding; the adhesive used in the present invention is an adhesive well known in the art, such as epoxy resin adhesive, polyurethane adhesive, acrylate adhesive, etc., and is not specifically limited thereto.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a backsheet that can be used in photovoltaic modules, providing high resistance to water vapor transmission and boiling. At the same time, the present invention utilizes inner co-extruded polyolefin material to maintain high thickness retention while also having high adhesion and interlayer adhesion with EVA film. Furthermore, the added plastic particles and fillers can work together with UV resistant agents to play a role in thermal conductivity and UV resistance, which can improve usability under temperature changes or humid conditions. Detailed Implementation

[0037] Example

[0038] Example 1

[0039] This example provides a backplate, including:

[0040] Inner layer: prepared by co-extrusion casting of a polyolefin adhesive layer and a polyolefin structural layer; the thickness of the prepared polyolefin adhesive layer is 50 μm, and the thickness of the polyolefin structural layer is 300 μm;

[0041] The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 20 parts of plastic particles, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, and 5 parts of triphenyl phosphite. The plastic particles are polyetheretherketone (PEEK) with a particle size of 35 μm, purchased from Changchun Jida University as PEEK 021FC30. The polyethylene is medium-density polyethylene (MDPE) FO A-6548BK and linear low-density polyethylene (LLDPE) 4105, with a weight ratio of 1:2.

[0042] The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 20 parts of polyethylene (HDPE) DGDA-6944NT, 20 parts of ethylene copolymer, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, 5 parts of triphenyl phosphite, and 20 parts of filler, which are carbon nanotubes LUCAN CP1002M and nano-magnesium oxide DK-MgO-001, with a weight ratio of 1:3. The ethylene copolymer includes binary ethylene copolymer POE 8480 and tertiary ethylene copolymer EPMD 3722P, with a weight ratio of 1:0.5.

[0043] Outer layer: includes an air layer and an aluminum plating layer. One side of the aluminum plating layer is connected to the air layer, and the other side is connected to the polyolefin structural layer. The thickness of the air layer is 50 μm, and the thickness of the aluminum plating layer is 40 nm. The raw materials for preparing the air layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 20 parts of polyethylene (HDPE) DGDA-6944 NT, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, 5 parts of triphenyl phosphite, and 15 parts of titanium dioxide. The air layer is formed by extrusion casting. The side of the air layer closest to the aluminum plating layer is electroplated.

[0044] This example also provides a method for preparing the olefin UV-resistant backsheet as described above, including: preparing the inner layer and the outer layer by adhesive bonding, wherein the adhesive used for adhesive bonding is an acrylic adhesive.

[0045] Example 2

[0046] This example provides a backplate, including:

[0047] Inner layer: prepared by co-extrusion casting of a polyolefin adhesive layer and a polyolefin structural layer; the thickness of the prepared polyolefin adhesive layer is 25 μm, and the thickness of the polyolefin structural layer is 250 μm;

[0048] The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 15 parts of plastic particles, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, and 4 parts of triphenyl phosphite. The plastic particles are polyetheretherketone (PEEK) with a particle size of 15 μm, purchased from Changchun Jida University as PEEK 021GF30. The polyethylene is medium-density polyethylene (MDPE) FO A-8864BK and linear low-density polyethylene (LLDPE) 4157, with a weight ratio of 1:1.2.

[0049] The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene (PP) EP-S31HP, 15 parts of polyethylene (HDPE) DGDP-6097NT, 15 parts of ethylene copolymer, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, 4 parts of triphenyl phosphite, and 15 parts of filler. The filler is carbon nanotube LUCAN CP1002M and nano magnesium oxide DK-MgO-001, with a weight ratio of 1:2.4. The ethylene copolymer includes binary ethylene copolymer POE8480 and ternary ethylene copolymer EPMD 3720P, with a weight ratio of 1:0.4.

[0050] Outer layer: includes an air layer and an aluminum plating layer. One side of the aluminum plating layer is connected to the air layer, and the other side is connected to the polyolefin structural layer. The thickness of the air layer is 30 μm, and the thickness of the aluminum plating layer is 30 nm. The raw materials for preparing the air layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 20 parts of polyethylene (HDPE) DGDA-6944 NT, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, 5 parts of triphenyl phosphite, and 15 parts of titanium dioxide. The air layer is formed by extrusion casting. The side of the air layer closest to the aluminum plating layer is electroplated.

[0051] This example also provides a method for preparing the olefin UV-resistant backsheet as described above, including: preparing the inner layer and the outer layer by adhesive bonding, wherein the adhesive used for adhesive bonding is an acrylic adhesive.

[0052] Example 3

[0053] This example provides a backplate, including:

[0054] Inner layer: prepared by co-extrusion casting of a polyolefin adhesive layer and a polyolefin structural layer; the thickness of the prepared polyolefin adhesive layer is 10 μm, and the thickness of the polyolefin structural layer is 150 μm;

[0055] The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 10 parts of plastic particles, 5 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 3 parts of antioxidant 2,6-di-tert-butylphenol, and 3 parts of triphenyl phosphite. The plastic particles are polyetheretherketone (PEEK) with a particle size of 6 μm, purchased from Changchun Jida University as PEEK 021CF20. The polyethylene is medium-density polyethylene (MDPE) FO A-8864BK and linear low-density polyethylene (LLDPE) 2535, with a weight ratio of 1:1.

[0056] The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene (PP) EP-S31HP, 10 parts of polyethylene (HDPE) DGDP-6097NT, 10 parts of ethylene copolymer, 5 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 3 parts of antioxidant 2,6-di-tert-butylphenol, 3 parts of triphenyl phosphite, and 10 parts of filler, which are carbon nanotubes LUCAN CP1002M and nano-magnesium oxide DK-MgO-001, with a weight ratio of 1:2. The ethylene copolymer includes binary ethylene copolymer POE 8450 and tertiary ethylene copolymer EPMD 3722P EL, with a weight ratio of 1:0.3.

[0057] Outer layer: includes an air layer and an aluminum plating layer. One side of the aluminum plating layer is connected to the air layer, and the other side is connected to the polyolefin structural layer. The thickness of the air layer is 10 μm, and the thickness of the aluminum plating layer is 10 nm. The raw materials for preparing the air layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 10 parts of polyethylene (HDPE) DGDA-6944 NT, 5 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 3 parts of antioxidant 2,6-di-tert-butylphenol, 3 parts of triphenyl phosphite, and 10 parts of titanium dioxide. The air layer is formed by extrusion casting. The side of the air layer closest to the aluminum plating layer is electroplated.

[0058] This example also provides a method for preparing the olefin UV-resistant backsheet as described above, including: preparing the inner layer and the outer layer by adhesive bonding, wherein the adhesive used for adhesive bonding is an acrylic adhesive.

[0059] Example 4

[0060] This example provides a backplate, including:

[0061] Inner layer: prepared by co-extrusion casting of a polyolefin adhesive layer and a polyolefin structural layer; the thickness of the prepared polyolefin adhesive layer is 25 μm, and the thickness of the polyolefin structural layer is 250 μm;

[0062] The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 15 parts of plastic particles, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, and 4 parts of triphenyl phosphite. The plastic particles are polyetheretherketone (PEEK) with a particle size of 15 μm, purchased from Changchun Jida University as PEEK 021GF30. The polyethylene is medium-density polyethylene (MDPE) FO A-8864BK and linear low-density polyethylene (LLDPE) 4157, with a weight ratio of 1:1.2.

[0063] The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene (PP) EP-S31HP, 15 parts of polyethylene (HDPE) DGDP-6097NT, 15 parts of ethylene copolymer, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, 4 parts of triphenyl phosphite, and 15 parts of filler, the filler being nano-magnesium oxide DK-MgO-001. The ethylene copolymer includes binary ethylene copolymer POE 8480 and tertiary ethylene copolymer EPMD 3720P, with a weight ratio of 1:0.4.

[0064] Outer layer: includes an air layer and an aluminum plating layer. One side of the aluminum plating layer is connected to the air layer, and the other side is connected to the polyolefin structural layer. The thickness of the air layer is 30 μm, and the thickness of the aluminum plating layer is 30 nm. The raw materials for preparing the air layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 20 parts of polyethylene (HDPE) DGDA-6944NT, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, 5 parts of triphenyl phosphite, and 15 parts of titanium dioxide. The air layer is formed by extrusion casting. The side of the air layer closest to the aluminum plating layer is electroplated.

[0065] This example also provides a method for preparing the olefin UV-resistant backsheet as described above, including: preparing the inner layer and the outer layer by adhesive bonding, wherein the adhesive used for adhesive bonding is an acrylic adhesive.

[0066] Example 5

[0067] This example provides a backplate, including:

[0068] Inner layer: prepared by co-extrusion casting of a polyolefin adhesive layer and a polyolefin structural layer; the thickness of the prepared polyolefin adhesive layer is 25 μm, and the thickness of the polyolefin structural layer is 250 μm;

[0069] The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 15 parts of plastic particles, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, and 4 parts of triphenyl phosphite. The plastic particles are polyetheretherketone (PEEK) with a particle size of 15 μm, purchased from Changchun Jida University as PEEK 021GF30. The polyethylene is medium-density polyethylene (MDPE) FO A-8864BK and linear low-density polyethylene (LLDPE) 4157, with a weight ratio of 1:1.2.

[0070] The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene (PP) EP-S31HP, 15 parts of polyethylene (HDPE) DGDP-6097NT, 15 parts of ethylene copolymer, 8 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 4 parts of antioxidant 2,6-di-tert-butylphenol, 4 parts of triphenyl phosphite, and 15 parts of filler, which are carbon nanotubes LUCAN CP1002M and nano-magnesium oxide DK-MgO-001, with a weight ratio of 1:2.4. The ethylene copolymer includes binary ethylene copolymer POE8480.

[0071] Outer layer: includes an air layer and an aluminum plating layer. One side of the aluminum plating layer is connected to the air layer, and the other side is connected to the polyolefin structural layer. The thickness of the air layer is 30 μm, and the thickness of the aluminum plating layer is 30 nm. The raw materials for preparing the air layer, by weight, include 100 parts of polypropylene (PP) EP-YS30RE, 20 parts of polyethylene (HDPE) DGDA-6944 NT, 10 parts of UV resistant agent 2-hydroxy-4-n-octyloxybenzophenone, 5 parts of antioxidant 2,6-di-tert-butylphenol, 5 parts of triphenyl phosphite, and 15 parts of titanium dioxide. The air layer is formed by extrusion casting. The side of the air layer closest to the aluminum plating layer is electroplated.

[0072] This example also provides a method for preparing the olefin UV-resistant backsheet as described above, including: preparing the inner layer and the outer layer by adhesive bonding, wherein the adhesive used for adhesive bonding is an acrylic adhesive.

[0073] Performance Evaluation

[0074] 1. Thickness retention rate: After the backing plate with an inner layer thickness of D0, EVA film, and glass provided in the example are laminated, the thickness D1 of the inner layer after the backing plate is laminated is observed under a microscope. The thickness retention rate is calculated as D1 / D0*100%. The results are shown in Table 1.

[0075] 2. Interlayer peel force: The inner layer provided in the example was tested for 180-degree interlayer peel force using a tensile testing machine. The results are shown in Table 1.

[0076] 3. Shrinkage rate: The shrinkage rate of the inner layer provided in the example was tested according to GB 13519, and the results are shown in Table 1.

[0077] 4. Water vapor transmission rate: The water vapor transmission rate of the backsheets provided in Examples 1-3 was calculated according to GB / T21529 at 23 degrees Celsius and 85% relative humidity. It was found that the water vapor transmission rate was less than 0.1 g·m⁻¹. -2 d -1 .

[0078] Table 1

[0079] Example Thickness retention rate % Interlayer peel force (N / cm) Shrinkage % 1 91 41 1.8 2 95 37 1 3 96 34 1.2 4 92 31 1.5 5 93 32 1.2

[0080] The test results show that the backsheet provided by the present invention has good water vapor barrier and heat resistance, and the thickness loss after hot pressing is small, so it can be used as the backsheet for a variety of photovoltaic modules.

Claims

1. A polyolefin UV-resistant backsheet, characterized in that, The back plate includes: Inner layer: prepared by co-extrusion of a polyolefin adhesive layer and a polyolefin structural layer; Outer layer: includes an air layer and an aluminum plating layer, wherein one side of the aluminum plating layer is connected to the air layer and the other side is connected to the polyolefin structural layer; The raw materials for preparing the polyolefin adhesive layer, by weight, include 100 parts of polyethylene, 10-50 parts of plastic particles, 1-10 parts of UV resistant agent, and 1-10 parts of antioxidant. The plastic particles are selected from at least one of polyamide, polycarbonate, polyethylene sulfide, polyethyl ether ketone, polyether ether ketone, and polyimide; The raw materials for preparing the polyolefin structural layer, by weight, include 100 parts of polypropylene, 10-20 parts of polyethylene, 10-20 parts of ethylene copolymer, 1-10 parts of UV resistant agent, and 1-10 parts of antioxidant. The polyolefin structural layer also includes 10 to 20 parts of filler, wherein the filler is selected from one or more of carbon nanotubes, nano magnesium oxide, titanium dioxide, and nano aluminum oxide.

2. The polyolefin UV-resistant backsheet according to claim 1, characterized in that, The polyethylene in the polyolefin adhesive layer is selected from at least one of low-density polyethylene, medium-density polyethylene, and linear low-density polyethylene.

3. The polyolefin UV-resistant backsheet according to claim 2, characterized in that, The medium-density polyethylene and linear low-density polyethylene are in a weight ratio of 1:1 to 2.

4. The polyolefin UV-resistant backsheet according to claim 1, characterized in that, The ethylene copolymer includes a binary ethylene copolymer, which is selected from one or more of POE, maleic anhydride grafts of homopolymer polyethylene, and silane grafts of homopolymer polyethylene.

5. The polyolefin UV-resistant backsheet according to claim 4, characterized in that, The ethylene copolymer further includes a terpolymer, which is selected from one or more of CO-ethylene-n-butyl acrylate terpolymer and ethylene-propylene-butadiene terpolymer.

6. A method for preparing a polyolefin UV-resistant backsheet according to any one of claims 1 to 5, characterized in that, include: The inner and outer layers are prepared by bonding them together.