A TPX high-temperature-resistant polyolefin three-layer composite film backplane and a preparation method thereof

Abstract

The application relates to H01L31 / 049 and particularly relates to a TPX high-temperature-resistant polyolefin three-layer composite film back plate and a preparation method thereof. The back plate comprises a barrier layer, a supporting layer and a bonding layer; the thickness ratio of the barrier layer, the supporting layer and the bonding layer is (70-90):(280-320):(20-40). The TPX high-temperature-resistant polyolefin three-layer composite film back plate provided by the application not only has reliable insulation and water resistance, but also has excellent high-temperature resistance and aging resistance, and is particularly suitable for preparing a solar cell back plate.

Description

Technical Field

[0001] This invention relates to H01L31 / 049, specifically to a TPX high-temperature resistant polyolefin three-layer composite film backsheet and its preparation method. Background Technology

[0002] Photovoltaic backsheets are a type of encapsulation material used on the back of solar modules to support and protect the solar cells. They typically employ a three-layer structure and possess reliable insulation, water resistance, and aging resistance properties.

[0003] Patent CN201610236772.4 describes a three-layer co-extruded one-time molding solar cell module backsheet. The backsheet is made of resin materials such as PA, PE, PP, and EVA, plus substances such as titanium dioxide. The resulting backsheet has advantages such as good mechanical properties and high reflectivity.

[0004] Patent CN201610149030.8 describes a three-layer integrated solar cell backsheet and its preparation method. The backsheet is prepared using PVDF, PMMMA, acrylic elastomers, acrylic toughening agents, antioxidants, UV absorbers, and other substances. It has advantages such as high adhesion, resistance to hydrolysis, and low cost.

[0005] Photovoltaic backsheets are exposed to the outdoors for extended periods and require sufficient durability against high temperatures, high humidity, and solar energy. However, backsheets prepared using existing technologies cannot fully meet these requirements. Therefore, this invention proposes a TPX high-temperature resistant polyolefin three-layer composite film backsheet and its preparation method, which exhibits excellent high-temperature resistance, water vapor barrier properties, and superior UV resistance. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the first aspect of the present invention provides a TPX high-temperature resistant polyolefin three-layer composite film backsheet, including a barrier layer, a support layer, and an adhesive layer; the thickness ratio of the barrier layer, support layer, and adhesive layer is (70-90):(280-320):(20-40).

[0007] Barrier layer

[0008] Preferably, the raw materials for preparing the barrier layer include: polyolefin copolymer, inorganic filler, and additives.

[0009] Preferably, the polyolefin copolymer includes at least one of polypropylene random copolymer, POE, EVA, TPX, TPV, and TPU.

[0010] More preferably, the polyolefin copolymer includes a random copolymer of polypropylene and TPX.

[0011] Preferably, the melt flow rate of the polypropylene random copolymer at 230℃ / 2.16kg is 5-10g / 10min.

[0012] More preferably, the melt flow rate of the polypropylene random copolymer at 230°C / 2.16 kg is 7 g / 10 min.

[0013] Preferably, the melt flow rate of the TPX at 260℃ / 5.0kg is 90-105g / 10min.

[0014] Preferably, the Vicat softening point of the TPX is 170-180℃, and the melting point is 220-240℃.

[0015] Solar cell composite film backsheets need to withstand high temperatures year-round. Over time, their performance deteriorates significantly. The inventors significantly improved the high-temperature resistance of the material by using TPX as the main material. They also unexpectedly discovered that when a specific amount of polypropylene is added to the barrier layer, and the melt flow rate of polypropylene is 7 g / 10 min, not only does the solar cell composite film backsheet have good high-temperature resistance, but it also avoids the problem of reduced gas barrier properties caused by a higher TPX content. This may be because the specific polypropylene allows the polypropylene segments of the molecular chain and inorganic particles such as fumed silica to embed into the helical structure of the TPX polymer during the melting process of the barrier layer raw material, and remain relatively stable without detaching.

[0016] Preferably, the inorganic filler includes at least one of carbon black, calcium carbonate, talc, titanium dioxide, mica powder, kaolin, wollastonite, diatomaceous earth, and fumed silica.

[0017] More preferably, the inorganic filler includes fumed silica and titanium dioxide.

[0018] Preferably, the specific surface area of ​​the fumed silica is 120-210 g / cm³. 2 .

[0019] Preferably, the fumed silica is hydrophobic fumed silica.

[0020] Preferably, the surface treatment reagent for the hydrophobic fumed silica is methylchlorosilane or hexamethylsilazane.

[0021] Preferably, the titanium dioxide content in the titanium dioxide is ≥90wt%.

[0022] Preferably, the titanium dioxide is rutile titanium dioxide.

[0023] Preferably, the additives include antioxidants, a first UV stabilizer, and a compatibilizer.

[0024] Preferably, the antioxidant comprises at least one of 2,4-dimethyl-6-tert-butylphenol, 1-hydroxy-3-methyl-4-isopropylbenzene, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), N,N'-di-2-naphthyl-p-phenylenediamine, and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0025] More preferably, the antioxidant comprises 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0026] Preferably, the weight ratio of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol is (3-7):(0.8-1.2).

[0027] More preferably, the weight ratio of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol is 5:1.

[0028] The inventors discovered that composite film backsheets using TPX as the main material would yellow after a period of time, affecting the appearance. However, after adding antioxidants and photosensitizers, the effect was not significant. The inventors unexpectedly discovered that when the antioxidant was a 5:1 weight ratio of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol, and the specific surface area of ​​fumed silica was 140-200 g / cm³, the effect was more pronounced. 2 However, it can significantly reduce yellowing resistance, possibly because the antioxidants and silica in this structure are less affected by the TPX helical structure, resulting in good dispersibility and avoiding active concentration of material molecular chains and carbon chain breakage.

[0029] Preferably, the first UV stabilizer includes at least one of UV-P, UV-O, UV-9, UV-531, UV-326, UV-327, UV-234, and UV-1164.

[0030] More preferably, the first UV stabilizer comprises UV-P and UV-O. The weight ratio of UV-P to UV-O is 1:(1.5-2.5).

[0031] Preferably, the raw materials for preparing the barrier layer, by weight, include: 10-20 parts of polypropylene random copolymer, 70-80 parts of TPX, 3-10 parts of titanium dioxide, 10-20 parts of fumed silica, 1-5 parts of antioxidant, 0.1-2 parts of primary UV stabilizer, and 2-3 parts of compatibilizer.

[0032] Preferably, the melt flow rate of the compatibilizer at 230℃ / 2.16kg is 145-160g / 10min.

[0033] Preferably, the compatibilizer comprises maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted polyethylene.

[0034] Preferably, the grafting rate of the compatibilizer is 1.3-1.6%.

[0035] support layer

[0036] Preferably, the raw materials for preparing the support layer, by weight, include: 90-100 parts of thermoplastic resin, 0.1-1 parts of alcohol ester compound, and 1-10 parts of second UV stabilizer.

[0037] Preferably, the melt flow rate of the thermoplastic resin at 260°C / 5kg is 22-28g / 10min.

[0038] Preferably, the thermoplastic resin includes at least one of PE, PP, PS, POM, PC, TPX, PVAc, and PMPA.

[0039] More preferably, the thermoplastic resin includes TPX.

[0040] Preferably, the alcohol ester compound includes octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and distearate thiodipropionate. The weight ratio of octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and distearate thiodipropionate is (0.5-2.5):1.

[0041] Preferably, the second UV stabilizer includes UV stabilizer KZ-1145.

[0042] Adhesive layer

[0043] Preferably, the raw materials for preparing the adhesive layer include: 20-30 parts TPX, 60-70 parts ethylene copolymer, 1-5 parts composite antioxidant, and 0.1-5 parts third UV stabilizer.

[0044] Preferably, the melt flow rate of the TPX at 260℃ / 5kg is 22-28g / 10min.

[0045] Preferably, the melt flow rate of the ethylene copolymer at 190°C / 2.16 kg is 50-60 g / 10 min.

[0046] Preferably, the ethylene copolymer includes at least one of ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, and ethylene-propylene copolymer.

[0047] More preferably, the ethylene copolymer is an ethylene-vinyl acetate copolymer.

[0048] Preferably, the VA content in the ethylene-vinyl acetate copolymer is 35-45 wt%.

[0049] Preferably, the composite antioxidant includes antioxidant 1010 and antioxidant 168.

[0050] Preferably, the third UV stabilizer includes UV stabilizer KZ-808A and / or UV stabilizer KZ-808B.

[0051] The second aspect of the present invention provides a method for preparing a TPX high-temperature resistant polyolefin three-layer composite film backsheet, comprising the following steps: mixing the raw materials of the barrier layer, support layer and adhesive layer uniformly in a high-speed mixer, melting and extruding them through a twin-screw extruder, and granulating them; obtaining barrier layer masterbatch, support layer masterbatch and adhesive layer masterbatch; and then placing the obtained barrier layer masterbatch, support layer masterbatch and adhesive layer masterbatch into a screw extruder and forming them through a three-layer co-extrusion casting equipment to obtain the final product.

[0052] Beneficial effects:

[0053] 1) By limiting the specific content and type of raw materials in each layer of the system, the present invention uses a three-layer co-extrusion method to prepare a polyolefin three-layer composite film backsheet including a barrier layer, a support layer and an adhesive layer. It not only has reliable insulation and water resistance, but also has excellent high temperature resistance and aging resistance, and is especially suitable for preparing solar cell backsheets.

[0054] 2) Solar cell composite film backsheets need to withstand high temperatures year-round. Over time, their performance deteriorates significantly. This invention uses TPX as the main material in conjunction with a polypropylene random copolymer with a melt flow rate of 5-10 g / 10 min to improve the high-temperature resistance of the polyolefin three-layer composite film backsheet. In particular, when the polypropylene random copolymer is 10-20 parts, it avoids the problem of reduced gas barrier properties caused by a higher TPX content, making the prepared polyolefin three-layer composite film backsheet more stable and preventing it from detaching.

[0055] 3) Composite film backsheets with TPX as the main material will yellow after a period of time, affecting their appearance. Further research in this invention revealed that when 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol are combined, especially at a weight ratio of (3-7):(0.8-1.2), the yellowing resistance is significantly reduced, while the specific surface area is 140-200 g / cm³. 2 The combined action of fumed silica and other substances prevents the formation of active concentrations in the material's molecular chains and the breakage of carbon chains.

[0056] 4) In addition, the present invention further specifies that TPX with a melt flow rate of 22-28 g / 10 min at 260℃ / 5 kg is used as the main material of the support layer, and ethylene-vinyl acetate copolymer with a melt flow rate of 22-28 g / 10 min at 260℃ / 5 kg and a melt flow rate of 50-60 g / 10 min at 190℃ / 2.16 kg is used as the main material of the adhesive layer. This results in high bonding strength between the three layers, avoiding damage to the component caused by delamination. In particular, when using ethylene-vinyl acetate copolymer with a VA content of 35-45 wt%, it has higher water vapor barrier performance, better encapsulation performance, and further improved adhesion and high temperature aging resistance.

[0057] 5) The barrier layer, support layer and adhesive layer of the present invention with a thickness ratio of (70-90):(280-320):(20-40) combined with the raw materials of each layer can more effectively absorb and utilize light, while making the product resistant to low temperature, with high aging performance, no cracking, and preventing delamination. Detailed Implementation

[0058] Example

[0059] Example 1

[0060] A TPX high-temperature resistant polyolefin three-layer composite film backsheet includes a barrier layer, a support layer, and an adhesive layer; the thickness ratio of the barrier layer, support layer, and adhesive layer is 80μm:300μm:30μm.

[0061] The raw materials for preparing the barrier layer, by weight, include: 15 parts of polypropylene random copolymer, 75 parts of TPX, 7 parts of titanium dioxide, 50 parts of fumed silica, 3 parts of antioxidant, 0.8 parts of first UV stabilizer, and 2 parts of compatibilizer.

[0062] The random copolymer of polypropylene has a melt flow rate of 7 g / 10 min at 230°C / 2.16 kg. The polypropylene was purchased from Singapore Polyolefins, product: FL7632L.

[0063] The TPX has a Vicat softening point of 172-178℃, a melting point of 232℃, and a melt flow rate of 100g / 10min at 260℃ / 5.0kg. It was purchased from Mitsui Chemicals, Japan, model: DX231.

[0064] The titanium dioxide content in the titanium dioxide is ≥92wt%, and the titanium dioxide is rutile titanium dioxide, purchased from Hunan Longbai New Materials Co., Ltd., model: R-9699.

[0065] The fumed silica is hydrophobic. The specific surface area of ​​the fumed silica is 140-200 g / cm³.2 Purchased from Shanghai Tikham Industrial Co., Ltd., Model: H20.

[0066] The antioxidant comprises 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol. The weight ratio of 1-hydroxy-3-methyl-4-isopropylbenzene to 2,6-di-tert-butyl-α-dimethylamino-p-cresol is 5:1. The 1-hydroxy-3-methyl-4-isopropylbenzene was purchased from Osaka Chemicals, model: Antioxidant HMPB; the 2,6-di-tert-butyl-α-dimethylamino-p-cresol was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., model: Antioxidant 703.

[0067] The first UV stabilizer comprises UV-P and UV-O. The weight ratio of UV-P to UV-O is 1:2. All of the first UV stabilizers were purchased from Changzhou Xince Polymer Materials Co., Ltd.

[0068] The compatibilizer has a melt flow rate of 150 g / 10 min at 230℃ / 2.16 kg, and the compatibilizer comprises maleic anhydride-grafted polypropylene with a grafting rate of 1.3-1.6%. It was purchased from Qingdao Youdian Chemical Co., Ltd.

[0069] The raw materials for preparing the support layer, by weight, include: 95 parts of thermoplastic resin, 0.8 parts of alcohol ester compound, and 3 parts of second UV stabilizer.

[0070] The thermoplastic resin has a melt flow rate of 25 g / 10 min at 260°C / 5 kg. The thermoplastic resin includes TPX, purchased from Mitsui Chemicals, Japan, model number MX004.

[0071] The alcohol ester compounds include octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and distearate thiodipropionate. The weight ratio of octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate to distearate thiodipropionate is 2:1. The octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is designated as Antioxidant 1076, and the distearate thiodipropionate is designated as Antioxidant DSTP. All alcohol ester compounds were purchased from Changzhou Xince Polymer Materials Co., Ltd.

[0072] The second UV stabilizer includes UV stabilizer KZ-1145, purchased from Changzhou Xince Polymer Materials Co., Ltd.

[0073] The raw materials for preparing the adhesive layer, by weight, include: 25 parts TPX, 65 parts ethylene copolymer, 3 parts composite antioxidant, and 2 parts third UV stabilizer.

[0074] The TPX had a melt flow rate of 26 g / 10 min at 260℃ / 5 kg and was purchased from Mitsui Chemicals, Japan, model: RT 18.

[0075] The ethylene copolymer has a melt flow rate of 55 g / 10 min at 190℃ / 2.16 kg. The ethylene copolymer is an ethylene-vinyl acetate copolymer with a VA content of 40 wt%, purchased from Dongguan Yiding Plastics Co., Ltd., model: Celanese 4030AC (USA).

[0076] The composite antioxidant comprises antioxidant 1010 and antioxidant 168. The mass ratio of antioxidant 1010 to antioxidant 168 is 1:2, and they are purchased from Changzhou Xince Polymer Materials Co., Ltd., model: antioxidant 215.

[0077] The third UV stabilizer includes UV stabilizer KZ-808A, manufactured by Changzhou Xince Polymer Materials Co., Ltd.

[0078] A method for preparing a TPX high-temperature resistant polyolefin three-layer composite film backsheet includes the following steps: mixing the raw materials of the barrier layer, support layer and adhesive layer uniformly in a high-speed mixer, melting and extruding them through a twin-screw extruder, and granulating them; obtaining barrier layer masterbatch, support layer masterbatch and adhesive layer masterbatch; and then placing the obtained barrier layer masterbatch, support layer masterbatch and adhesive layer masterbatch into a screw extruder and forming them through a three-layer co-extrusion casting equipment to obtain the final product.

[0079] Example 2

[0080] A TPX high-temperature resistant polyolefin three-layer composite film backsheet, the specific implementation method is the same as that in Example 1, the difference being that the raw materials for preparing the adhesive layer include: 30 parts TPX, 70 parts ethylene copolymer, 3 parts composite antioxidant, and 2 parts third UV stabilizer.

[0081] Example 3

[0082] A TPX high-temperature resistant polyolefin three-layer composite film backsheet, the specific implementation method is the same as that in Example 1, the difference being that the raw materials for preparing the barrier layer include: 20 parts of polypropylene random copolymer, 80 parts of TPX, 10 parts of titanium dioxide, 20 parts of fumed silica, 3 parts of antioxidant, 1.8 parts of first anti-ultraviolet agent, and 2 parts of compatibilizer.

[0083] Comparative Example 1

[0084] A TPX high-temperature resistant polyolefin three-layer composite film backsheet is implemented in the same way as in Example 1, except that the weight ratio of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol is 1:1.

[0085] Comparative Example 2

[0086] A TPX high-temperature resistant polyolefin three-layer composite film backsheet is described, with the specific implementation method being the same as in Example 1, except that the melt flow rate of the polypropylene random copolymer at 230℃ / 2.16kg is 12g / 10min. The polypropylene was purchased from ExxonMobil. TM PP9574E6.

[0087] Performance testing

[0088] 1. High Temperature Resistance Test: Polycrystalline silicon 156mm*156mm cells were used to construct crystalline silicon modules. Hot spot durability testing was conducted according to GB / T9535-2005, using 8 modules connected in series. Irradiation source 1 was 800W / m². 2 Irradiation source 2 is 1000W / m 2 Test the attenuation value of the maximum power.

[0089] 2. Yellowing resistance test: The backing materials obtained in the examples and comparative examples were pretreated with 15KW·h / m2 UV light, and then the backing materials were placed in an autoclave and treated at 180°C and 100%RH for 36 hours. Yellowing was observed.

[0090] Table 1 Performance Test Results

[0091] Attenuation value Yellowing resistance Example 1 1.00％ No yellowing Example 2 1.25％ No yellowing Example 3 1.37％ No yellowing Comparative Example 1 1.51％ Yellowing Comparative Example 2 2.32％ Yellowing

Claims

1. A TPX high-temperature resistant polyolefin three-layer composite film backsheet, characterized in that, It includes a barrier layer, a support layer, and an adhesive layer; the thickness ratio of the barrier layer, support layer, and adhesive layer is (70-90):(280-320):(20-40); The raw materials for preparing the barrier layer include: polyolefin copolymer, inorganic filler, and additives; The polyolefin copolymer includes a random copolymer of polypropylene and TPX; The melt flow rate of the polypropylene random copolymer at 230℃ / 2.16kg is 5-10g / 10min; The additives include antioxidants, primary UV stabilizers, and compatibilizers; The antioxidant comprises 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol in a weight ratio of (3-7):(0.8-1.2). The inorganic filler includes at least one of carbon black, calcium carbonate, talc, titanium dioxide, mica powder, kaolin, wollastonite, diatomaceous earth, and fumed silica. The specific surface area of ​​the fumed silica is 140-200 g / cm³. 2 .

2. The TPX high-temperature resistant polyolefin three-layer composite film backsheet according to claim 1, characterized in that, The titanium dioxide content in the titanium dioxide is ≥90wt%.

3. The TPX high-temperature resistant polyolefin three-layer composite film backsheet according to claim 1, characterized in that, The first UV protectant includes at least one of UV-P, UV-O, UV-9, UV-531, UV-326, UV-327, UV-234, and UV-1164.

4. A method for preparing a TPX high-temperature resistant polyolefin three-layer composite film backsheet according to claim 1, characterized in that, Includes the following steps: The raw materials for the barrier layer, support layer, and adhesive layer are mixed evenly in a high-speed mixer, then melt-extruded and granulated through a twin-screw extruder to obtain barrier layer masterbatch, support layer masterbatch, and adhesive layer masterbatch. The obtained barrier layer masterbatch, support layer masterbatch, and adhesive layer masterbatch are then fed into a screw extruder and formed by a three-layer co-extrusion casting equipment to obtain the final product.