Packaging material for photovoltaic module and preparation method thereof

Abstract

The invention relates to the technical field of photovoltaic packaging materials, and discloses a packaging material for a photovoltaic module and a preparation method of the packaging material. The preparation method comprises the following steps: firstly, respectively preparing the hydrolysis-resistant master batch, the ultraviolet absorption master batch and the light-stable master batch; then respectively preparing weather-resistant layer master batches (containing hydrolysis-resistant master batches, ultraviolet absorption master batches, light-stable master batches and modified polyester chips in specific parts by weight), core layer master batches (containing modified polyester chips and connecting particles in specific parts by weight) and bonding layer master batches (containing bonding materials, modified polyester chips and hydrolysis-resistant master batches in specific parts by weight); and carrying out three-layer co-extrusion and cooling on the weather-resistant layer master batch, the core layer master batch and the bonding layer master batch in specific parts by weight, and then carrying out two-way stretching, sizing and cooling to obtain the packaging material for the photovoltaic module. The packaging material is formed at a time through co-extrusion double-drawing, the processes of coating a coating and / or compounding other materials and the like do not need to be added, and the packaging material is simple in process, low in cost, excellent in comprehensive performance and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic packaging materials, and in particular to a packaging material for a photovoltaic module and a preparation method thereof. Background Art

[0002] Traditional photovoltaic backsheets all use PET (polyethylene terephthalate) as the skeleton structure, and use fluorine film or fluorocarbon coating as the weather-resistant layer. Therefore, the traditional photovoltaic backsheet is a three-layer sandwich structure (such as the CPC photovoltaic backsheet formed by the three layers of fluorocarbon coating / PET substrate / inner coating), and its production process often requires 2-4 processes (such as single coating, double coating, slitting, or single coating, compounding, aging, slitting) to complete the production, so the production efficiency is not high and the labor cost is huge.

[0003] Therefore, in order to improve the production efficiency of photovoltaic backsheets, the following existing photovoltaic encapsulation materials have been developed: As shown in the publication number CN115625870A, a super weather-resistant white polyester film and its preparation method are disclosed. The super weather-resistant white polyester film is composed of a core layer and upper and lower surface layers. The raw materials of the core layer are tackifying polyester chips, anti-hydrolysis masterbatch and white masterbatch in a mass ratio of 82~95:2~8:3~10, and the raw materials of the upper and lower surface layers are tackifying polyester chips, white masterbatch and anti-ultraviolet masterbatch in a mass ratio of 55~84:15~35:1~10; the preparation method is: respectively mixing the constituent raw materials of the core layer and the constituent raw materials of the surface layer and then melt-extruding them, extruding the melt through a three-layer co-extrusion die head, casting a sheet, and then biaxially stretching to obtain a super weather-resistant white polyester film. The light transmittance of the super weather-resistant white polyester film is ≤30%, the transmittance at an ultraviolet wavelength of 380nm is ≤5%, the elongation at break after PCT72 hours is ≥40%, and the △b after ultraviolet irradiation of 200kWh is ≤3. However, due to the influence of the preparation method of the super weather-resistant white polyester film shown in publication number CN115625870A (for example, before the three-layer co-extrusion, the constituent raw materials of the surface layer and the constituent raw materials of the core layer are not prepared as functional layer masterbatch in advance) and the raw material formula of each layer (for example, there are no particles with excellent connecting effect between the surface layer and the core layer), the tensile strength, elongation at break, heat shrinkage, resistance to UV, moisture, heat, aging and yellowing, and bonding performance with EVA film or silicone rubber film of this super weather-resistant white polyester film still need to be improved.

[0004] As shown in publication number CN109473498A, a packaged integrated backplane and its preparation method are disclosed. The packaged integrated backplane has good water-blocking properties, good adhesion to solar cells, no photothermal aging after long-term use, no corrosion to the cells, no use of adhesives, good environmental protection, easy recycling, good weather resistance, and no obvious yellowing after long-term use. However, the existing packaged integrated backplane uses polyolefin as the skeleton structure and TPO (thermoplastic polyolefin) particle material layer as the connecting layer; moreover, before the three-layer co-extrusion, no functional masterbatch and functional layer masterbatch are prepared in advance. Therefore, the performance of this packaged integrated backplane needs to be improved in terms of tensile strength, elongation at break, thermal shrinkage, resistance to ultraviolet and heat aging and yellowing, and retention rate of elongation at break after PCT48h. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a packaging material for a photovoltaic module and a preparation method thereof.

[0006] Based on this, the present invention discloses a method for preparing a packaging material for a photovoltaic module, comprising the following preparation steps: Step 1: Preparation of functional masterbatch: The anti-hydrolysis agent and the modified polyester chips are uniformly mixed in a mass ratio of 7-20:100, and then melt-extruded and granulated to obtain an anti-hydrolysis masterbatch; The ultraviolet absorber and the modified polyester chips are uniformly mixed in a mass ratio of 5-25:100, and then melt-extruded and granulated to obtain ultraviolet absorbing masterbatch; The light stabilizer and the modified polyester chips are uniformly mixed in a mass ratio of 1-3:100, and then melt-extruded and granulated to obtain a light-stabilized masterbatch; Step 2: Preparation of functional layer masterbatch: By weight, 10-30 parts of anti-hydrolysis masterbatch, 5-20 parts of ultraviolet absorption masterbatch, 5-10 parts of light-stabilizing masterbatch and 185-230 parts of modified polyester chips are mixed evenly, and then melt-extruded and granulated to obtain weather-resistant layer masterbatch; By weight, 70-80 parts of modified polyester chips and 20-30 parts of connecting particles (particles capable of bonding) are mixed evenly, and then melt-extruded and granulated to obtain a core layer masterbatch; By weight, 20-60 parts of adhesive, 20-50 parts of modified polyester chips and 2-10 parts of anti-hydrolysis masterbatch are mixed evenly, and then melt-extruded and granulated to obtain a bonding layer masterbatch; Step 3, by weight, 100-175 parts of weather-resistant layer masterbatch, 200-300 parts of core layer masterbatch, and 50-70 parts of bonding layer masterbatch are respectively put into the A machine, B machine, and C machine of the co-extrusion equipment, and the masterbatch of each layer is melted and co-extruded in three layers, and cooled to obtain a cast sheet; Step 4: The casting sheet is subjected to biaxial stretching, shaping and cooling in sequence to obtain a packaging material for photovoltaic modules.

[0007] Preferably, the modified polyester chips are acid-modified polyester chips, with a discharge temperature of 260-285°C, an intrinsic viscosity of 0.7-0.9 dL / g, a terminal carboxyl range of 20-30 mol / t, and a melting point in the range of 252-262°C.

[0008] Preferably, the anti-hydrolysis agent is at least one of monomeric carbodiimide, polycarbodiimide, and oxazoline-type compounds; the anti-hydrolysis agent is preferably carbodiimide.

[0009] Preferably, the ultraviolet absorber is at least one of a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a triazine ultraviolet absorber; the ultraviolet absorber is preferably a UV239 ultraviolet absorber.

[0010] The light stabilizer is a hindered amine light stabilizer; the light stabilizer is preferably BASF light stabilizer UV791.

[0011] Preferably, in step 1, the preparation of the anti-hydrolysis masterbatch, the ultraviolet absorption masterbatch and the light-stabilizing masterbatch is carried out by uniformly mixing in a double-cone rotary mixer, the speed of the double-cone rotary mixer is controlled to be 8-12 rpm, and the mixing time is less than or equal to 1 hour.

[0012] Preferably, the connecting particles are the following resin particles F534A, M545, M704, M603, P553A, P565, F502C, F535, ADMER™, BYNEL™2200, NUCREL™, Plexar PX3080, Plexar ® The connecting particles are preferably resin particles F534A, which are produced by Mitsubishi Chemical Functional Plastics (China) Co., Ltd. Among them, the manufacturer of the above F, M, and P series resins is Mitsubishi Chemical Functional Plastics (China) Co., Ltd.

[0013] Preferably, the adhesive is the following olefin resin VESTOPLAST ® 206. VESTOPLAST ® 206 EPP、VESTOPLAST ® 308. VESTOPLAST ® 508.VESTOPLAST ® 608, VESTOPLAST ® 704、VESTOPLAST ® 750, VESTOPLAST ® 792. VESTOPLAST® EP V2094、VESTOPLAST ® 828, VESTOPLAST ® 891、VESTOPLAST ® At least one of SR, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene; the adhesive is preferably an olefin resin VESTOPLAST ® 206. Among them, Vestoplast series is olefin resin of Evonik Specialty Chemicals (Shanghai) Co., Ltd.

[0014] Preferably, in step 2, the preparation of the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch are all carried out by the uniform mixing operation in a double-cone rotary mixer, and the melt extrusion granulation operation is carried out by a twin-screw extruder, the extrusion temperature is 200-280°C, and the screw speed is 5-13rpm.

[0015] Preferably, step 3 specifically includes: putting the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch into the A machine, the B machine and the C machine of the co-extrusion equipment respectively, drying them at 150-170°C for 2-4h, adjusting the melt pump flow ratio of the A machine, the B machine and the C machine to 1-3:2-4:0.5-1 respectively, and melt-mixing the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch through the three single-screw extruders ABC respectively, and then extruding them through three-layer co-extrusion at 200-280°C, and rapidly cooling them through a 3-10°C chill roller to make a cast sheet.

[0016] In step 3, by adjusting the melt pump flow rates of machines A, B, and C online, production switching of packaging materials for different product types can be achieved, and packaging materials for different product types can be directly processed to meet different demands for packaging materials in different application scenarios.

[0017] Polyester can form crystals within the range between the melting point and the glass transition temperature. Therefore, the main function of the chill roll is to form a transparent amorphous packaging material through the rapid cooling of the melt.

[0018] Preferably, the step 4 specifically includes: asynchronously stretching the cast sheet, with a transverse stretching ratio of 1-3.5 times, a longitudinal stretching ratio of 1-3.5 times, a preheating time of 80-150s, a stretching temperature of 90-120°C, a setting temperature of 200-230°C, a setting time of 10-30s, and after cooling roller extrusion, cooling, pulling, trimming, and winding, the packaging material for the photovoltaic module is obtained.

[0019] The present invention also discloses a packaging material for a photovoltaic module, which is prepared by the preparation method of the packaging material for a photovoltaic module described above in the present invention; The packaging material for photovoltaic modules is applied to the back of photovoltaic modules (especially single-glass photovoltaic modules), and includes a weather-resistant layer (made of weather-resistant layer masterbatch), a core layer (made of the above-mentioned core layer masterbatch) and a bonding layer (made of the above-mentioned bonding layer masterbatch) formed in one step by co-extrusion and double-drawing. The weather-resistant layer and the bonding layer are respectively provided on the upper and lower surfaces of the core layer.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The packaging material for photovoltaic modules of the present invention is formed by intra-film compounding and online double-drawing in one step through a three-layer co-extrusion device. There is no need to go through subsequent processes such as coating and / or compounding other materials with adhesives. No adhesive is used, and no fluorocarbon coating is required. There is no VOC emission, which greatly saves energy consumption and material costs. The processing cost is low, continuous production can be achieved, no separate maintenance is required, the processing technology is simple, and recycling can be achieved.

[0021] 2. Compared with the conventional three-layer co-extruded PET photovoltaic encapsulation film on the market, the encapsulation material for photovoltaic modules prepared by the present invention firstly mixes a certain amount of anti-hydrolysis agent, ultraviolet absorber and light stabilizer with modified polyester chips respectively, and melts and extrudes them to obtain anti-hydrolysis masterbatch, ultraviolet absorption masterbatch and light stabilization masterbatch. Then, on the basis of the weather-resistant layer masterbatch composed of the above-mentioned raw materials in weight ratio, the core layer masterbatch composed of the above-mentioned raw materials in weight ratio and the bonding layer masterbatch composed of the above-mentioned raw materials in weight ratio are used. The masterbatch of each layer is formed by co-extrusion and double-drawing at one time; therefore, the structural defects of the encapsulation material are few, and in the long-term aging test (ultraviolet absorption), the UV absorption masterbatch is less than 0.05. The elongation at break retention rate in the process of UV, humidity and heat, and pressure cooking is high, and the yellowing caused by UV, humidity and heat aging is small. At the same time, the packaging material has excellent tensile strength and elongation at break, low UV light transmittance and low MD (longitudinal) thermal shrinkage. The core layer made of the core layer masterbatch is used as the middle layer, so that the weather-resistant layer and the bonding layer are more closely connected without stratification. In combination with the bonding layer, the bonding performance of the packaging material to different films (such as EVA films and silicone) can be improved without using coatings or adhesives, thereby improving the peeling force and having universal bonding properties. Therefore, the packaging material is applied to the back of photovoltaic modules (especially single-glass photovoltaic modules) to effectively improve the service life of photovoltaic modules. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0023] The modified polyester chips in the following examples and comparative examples are acid-modified polyester chips, with a discharge temperature of 270°C, an intrinsic viscosity of 0.8 dL / g, a terminal carboxyl range of 28 mol / t, and a melting point in the range of 261°C.

[0024] Example 1 A method for preparing a packaging material for a photovoltaic module in this embodiment includes the following preparation steps: Step 1: Preparation of functional masterbatch: Preparation of anti-hydrolysis masterbatch: 10 parts (weight parts, the same below) of anti-hydrolysis agent and 135 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 10rpm, the mixing time is 0.5h, and the mixed particles are melt extruded and granulated through a twin screw extruder to obtain anti-hydrolysis masterbatch. Among them, the anti-hydrolysis agent is carbodiimide.

[0025] Preparation of UV absorber masterbatch: 5 parts of UV absorber and 100 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 8 rpm, the mixing time is 1 hour, and the mixed particles are melt extruded and granulated by a twin screw extruder to obtain UV absorber masterbatch. Among them, the UV absorber is UV239 UV absorber.

[0026] Preparation of light-stabilized masterbatch: 2 parts of light stabilizer and 100 parts of modified polyester chips were mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer was controlled to be 8 rpm, the mixing time was 1 hour, and the mixed particles were melt extruded and granulated through a twin screw extruder to obtain light-stabilized masterbatch. Among them, the light stabilizer was BASF light stabilizer UV791.

[0027] Step 2: Preparation of functional layer masterbatch: Preparation of weather-resistant layer masterbatch: 20 parts of anti-hydrolysis masterbatch, 8 parts of UV absorption masterbatch, 9 parts of light-stabilizing masterbatch and 193 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated through a twin-screw extruder. The extrusion temperature is 275°C and the screw speed is 13rpm to obtain the weather-resistant layer masterbatch.

[0028] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles were mixed evenly in a double cone rotary mixer, and then melt extruded and granulated by a twin screw extruder at an extrusion temperature of 275°C and a screw speed of 13 rpm to obtain core layer masterbatch. The connecting particles were resin particles F534A.

[0029] Preparation of bonding layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of anti-hydrolysis masterbatch were mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated by a twin-screw extruder at an extrusion temperature of 275°C and a screw speed of 12rpm to obtain the bonding layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0030] Step 3, 175 parts of weather-resistant layer masterbatch, 200 parts of core layer masterbatch, and 50 parts of bonding layer masterbatch are respectively put into machine A, machine B, and machine C of the co-extrusion equipment. After drying at 160°C for 4 hours, the melt pump flow ratio of machine A, machine B, and machine C is adjusted to 1:1.03:0.5, respectively. The weather-resistant layer masterbatch, core layer masterbatch, and bonding layer masterbatch are melt-mixed by the three single-screw extruders ABC, respectively, and extruded by three-layer co-extrusion at 265°C, and rapidly cooled by a 5°C chill roller to make a cast sheet.

[0031] Step 4: The cast sheet is asynchronously stretched, with the transverse stretching ratio and the longitudinal stretching ratio both being 3 times, the preheating time being 90 seconds, the stretching temperature being 95°C, the setting temperature being 220°C, and the setting time being 10 seconds. After being extruded by a cooling roller, cooled, pulled, trimmed, and rolled up, a packaging material for a photovoltaic module in this embodiment is obtained.

[0032] The encapsulation material for photovoltaic modules of this embodiment includes a weather-resistant layer, a core layer and an adhesive layer stacked in sequence, and the weather-resistant layer and the adhesive layer are connected through the core layer; and the weather-resistant layer masterbatch (used to prepare the weather-resistant layer), the core layer masterbatch (used to prepare the core layer), and the adhesive layer masterbatch (used to prepare the adhesive layer) are respectively co-extruded into cast sheets through three single-screw extruders through in-film composite three-layer co-extrusion, and then directly stretched through a double-drawing process. Among them, the total thickness of the encapsulation material is 285μm, and the thickness ratio of the weather-resistant layer, the core layer and the adhesive layer is 1:2:1.

[0033] Example 2 A method for preparing a packaging material for a photovoltaic module in this embodiment includes the following preparation steps: Step 1: Preparation of functional masterbatch: Preparation of anti-hydrolysis masterbatch: 15 parts of anti-hydrolysis agent (parts by weight, the same below) and 120 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 12rpm, the mixing time is 0.8h, and the mixed particles are melt-extruded and granulated through a twin-screw extruder to obtain anti-hydrolysis masterbatch. Among them, the anti-hydrolysis agent is carbodiimide.

[0034] Preparation of UV absorber masterbatch: 15 parts of UV absorber and 100 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 9 rpm, the mixing time is 1 hour, and the mixed particles are melt extruded and granulated by a twin screw extruder to obtain UV absorber masterbatch. The UV absorber is UV239 UV absorber.

[0035] Preparation of light-stabilized masterbatch: 2 parts of light stabilizer and 100 parts of modified polyester chips were mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer was controlled to be 8 rpm, the mixing time was 1 hour, and the mixed particles were melt extruded and granulated through a twin screw extruder to obtain light-stabilized masterbatch. Among them, the light stabilizer was BASF light stabilizer UV791.

[0036] Step 2: Preparation of functional layer masterbatch: Preparation of weather-resistant layer masterbatch: 15 parts of anti-hydrolysis masterbatch, 10 parts of UV absorption masterbatch, 7 parts of light-stabilizing masterbatch and 198 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated through a twin-screw extruder. The extrusion temperature is 265°C and the screw speed is 12rpm to obtain the weather-resistant layer masterbatch.

[0037] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles were mixed evenly in a double cone rotary mixer, and then melt extruded and granulated by a twin screw extruder at an extrusion temperature of 275°C and a screw speed of 13 rpm to obtain core layer masterbatch. The connecting particles were resin particles F534A.

[0038] Preparation of bonding layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of anti-hydrolysis masterbatch were mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated by a twin-screw extruder at an extrusion temperature of 275°C and a screw speed of 12rpm to obtain the bonding layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0039] Step 3, 150 parts of weather-resistant layer masterbatch, 300 parts of core layer masterbatch, and 70 parts of bonding layer masterbatch are respectively put into machine A, machine B, and machine C of the co-extrusion equipment. After drying at 170°C for 3 hours, the melt pump flow ratio of machine A, machine B, and machine C is adjusted to 1:1.5:0.5, respectively. The weather-resistant layer masterbatch, core layer masterbatch, and bonding layer masterbatch are melt-mixed by the three single-screw extruders ABC, respectively, and extruded by three-layer co-extrusion at 270°C, and rapidly cooled by a 3°C chill roller to make a cast sheet.

[0040] Step 4: asynchronously stretch the cast sheet with a transverse stretching ratio of 3.3 times, a longitudinal stretching ratio of 3 times, a preheating time of 120 seconds, a stretching temperature of 100°C, a setting temperature of 220°C, and a setting time of 15 seconds. After extrusion with a cooling roller, cooling, pulling, trimming, and winding, a packaging material for a photovoltaic module in this embodiment is obtained.

[0041] The specific structure of the packaging material for a photovoltaic module in this embodiment is similar to that in Embodiment 1 and will not be described in detail here.

[0042] Example 3 A method for preparing a packaging material for a photovoltaic module in this embodiment includes the following preparation steps: Step 1: Preparation of functional masterbatch: Preparation of anti-hydrolysis masterbatch: 30 parts of anti-hydrolysis agent (parts by weight, the same below) and 150 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 10rpm, the mixing time is 0.5h, and the mixed particles are melt-extruded and granulated through a twin-screw extruder to obtain anti-hydrolysis masterbatch. Among them, the anti-hydrolysis agent is carbodiimide.

[0043] Preparation of UV absorber masterbatch: 20 parts of UV absorber and 80 parts of modified polyester chips are mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer is controlled to be 12 rpm, the mixing time is 1 hour, and the mixed particles are melt extruded and granulated by a twin screw extruder to obtain UV absorber masterbatch. The UV absorber is UV239 UV absorber.

[0044] Preparation of light-stabilized masterbatch: 2 parts of light stabilizer and 100 parts of modified polyester chips were mixed evenly in a double cone rotary mixer, the speed of the double cone rotary mixer was controlled to be 8 rpm, the mixing time was 1 hour, and the mixed particles were melt extruded and granulated through a twin screw extruder to obtain light-stabilized masterbatch. Among them, the light stabilizer was BASF light stabilizer UV791.

[0045] Step 2: Preparation of functional layer masterbatch: Preparation of weather-resistant layer masterbatch: 12 parts of anti-hydrolysis masterbatch, 15 parts of UV absorption masterbatch, 5 parts of light-stabilizing masterbatch and 198 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated through a twin-screw extruder. The extrusion temperature is 275°C and the screw speed is 12rpm to obtain the weather-resistant layer masterbatch.

[0046] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles were mixed evenly in a double cone rotary mixer, and then melt extruded and granulated by a twin screw extruder at an extrusion temperature of 275°C and a screw speed of 13 rpm to obtain core layer masterbatch. The connecting particles were resin particles F534A.

[0047] Preparation of bonding layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of anti-hydrolysis masterbatch were mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated by a twin-screw extruder at an extrusion temperature of 275°C and a screw speed of 12rpm to obtain the bonding layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0048] Step 3, put 100 parts of weather-resistant layer masterbatch, 200 parts of core layer masterbatch, and 50 parts of bonding layer masterbatch into the A machine, B machine, and C machine of the co-extrusion equipment respectively, and after drying at 170°C for 3 hours, adjust the melt pump flow ratio of machines A, B, and C to 1:2:0.5 respectively, and melt-mix the weather-resistant layer masterbatch, core layer masterbatch, and bonding layer masterbatch through the three single-screw extruders ABC respectively, and extrude them through three-layer co-extrusion at 270°C, and rapidly cool them through a 3°C chill roller to make a cast sheet.

[0049] Step 4: asynchronously stretch the cast sheet with a transverse stretching ratio of 3.3 times, a longitudinal stretching ratio of 3 times, a preheating time of 120 seconds, a stretching temperature of 100°C, a setting temperature of 220°C, and a setting time of 15 seconds. After extrusion with a cooling roller, cooling, pulling, trimming, and winding, a packaging material for a photovoltaic module in this embodiment is obtained.

[0050] The specific structure of the packaging material for a photovoltaic module in this embodiment is similar to that in Embodiment 1 and will not be described in detail here.

[0051] Comparative Example 1 The packaging material for a photovoltaic module and the preparation method thereof in this comparative example are all referred to Example 1, and the difference between them and Example 1 is that: In the preparation method of a packaging material for a photovoltaic module in this comparative example, the core layer masterbatch of Example 1 is directly replaced with modified polyester chip particles (the modified polyester chip particles are prepared as follows: 100 parts by weight of modified polyester chips are mixed evenly in a double-cone rotary mixer, and then melt-extruded and granulated through a twin-screw extruder to obtain modified polyester chip particles), and the thickness of each layer remains unchanged, thereby obtaining a packaging material for a photovoltaic module in this comparative example.

[0052] Comparative Example 2 The packaging material for a photovoltaic module and the preparation method thereof in this comparative example are all referred to Example 1, and the difference between them and Example 1 is that: In the preparation method of a packaging material for a photovoltaic module in this comparative example, the bonding layer masterbatch of Example 1 is directly replaced with an anti-hydrolysis masterbatch (the preparation process of the anti-hydrolysis masterbatch refers to the preparation of the anti-hydrolysis masterbatch in step 1 of Example 1), and the thickness of each layer remains unchanged, thereby obtaining a packaging material for a photovoltaic module in this comparative example.

[0053] Comparative Example 3 A photovoltaic module packaging material in this comparative example directly uses a conventional three-layer co-extruded PET photovoltaic packaging film on the market. The three-layer co-extruded PET photovoltaic packaging film is: Jiangsu Yuxing Film Technology Co., Ltd. (CY25HT (GU) UV-resistant transparent polyester film for solar backing); the thickness ratio of layer A: layer B: layer A is 1:2:1, layer A is a weather-resistant layer, layer B is an intermediate layer, and the total thickness of the three layers is 285μm.

[0054] Comparative Example 4 A packaging material for a photovoltaic module in this comparative example directly adopts a conventional CPC photovoltaic back film on the market (a composite material with polycarbonate as a substrate and a fluorocarbon coating on the surface). The CPC photovoltaic back film is: Zhonglai Photovoltaic FFCJW3010P, which has a 20μm weather-resistant coating, a 275μm PET substrate and a 10μm inner coating layer stacked in sequence.

[0055] Performance Testing The performance tests were performed on the packaging materials for photovoltaic modules of Examples 1-3 and Comparative Examples 1-4. The test results are shown in Table 1 below. In Table 1, UV+DH30 (kWh / m 2 ) is a composite aging test, and its test conditions are: under DH conditions (temperature 85°C, humidity 85%), the UV radiation reaches 30kWh / m 2 .

[0056] Table 1

[0057] From Table 1 above, we can see that: The MD heat shrinkage rate of the packaging material for photovoltaic modules of Examples 1-3 is lower than that of Comparative Example 1, and the MD heat shrinkage rate of the packaging material for photovoltaic modules of Comparative Example 1 is greater than 0.6%; therefore, in the process of preparing the packaging material for photovoltaic modules in Comparative Example 1, it is necessary to perform a stretching and heat setting process, otherwise the photovoltaic modules will be poorly made. It should be noted that, at present, photovoltaic packaging materials or photovoltaic backsheets generally require an MD heat shrinkage rate of less than 0.6%, which is for the latest photovoltaic modules. The gap between the cells of conventional photovoltaic modules is large, and the MD heat shrinkage rate is larger, which will not cause the adjacent cells to be paralleled. However, the current photovoltaic modules pursue greater efficiency and power generation, so the gap between the cells is required to be very small, usually 1-2mm (the original gap between the cells is 4-5mm); the gap between the cells is small, and when the photovoltaic packaging material shrinks slightly during lamination, it will cause the movement of the cells, causing the cells to be stacked (that is, paralleled), which will lead to a large number of poorly made photovoltaic modules.

[0058] If a weather-resistant layer + an adhesive layer or a weather-resistant layer + a modified polyester chip particle layer without connecting particles + an adhesive layer (as shown in Comparative Example 1) is directly used, the adhesive layer and other layers are easily separated and difficult to be integrated through co-extrusion molding.

[0059] Compared with Comparative Example 1 (Comparative Example 1 directly replaces the core layer masterbatch of Example 1 with modified polyester chip particles), the MD thermal shrinkage of the photovoltaic module packaging materials of Examples 1-3 is less than 0.6%. At the same time, the elongation at break retention of the photovoltaic module packaging materials of Examples 1-3 after PCT48h treatment is greater than 40%; and, compared with Comparative Example 1-2 (Comparative Example 2 directly replaces the bonding layer masterbatch of Example 1 with anti-hydrolysis masterbatch), the photovoltaic module packaging materials of Examples 1-3 also have greater tensile strength and elongation at break, smaller MD thermal shrinkage and better bonding performance (the photovoltaic module packaging materials of Examples 1-3 have better bonding strength for various types of adhesive films and silicones, and have a wide range of bonding properties). Therefore, the photovoltaic module packaging materials of Examples 1-3 can more effectively improve the service life of photovoltaic modules.

[0060] Compared with Examples 1-3, the conventional three-layer co-extruded PET photovoltaic packaging film currently on the market (as shown in Comparative Example 3) has a high UV transmittance, high resistance to UV, moisture, heat, aging and yellowing, and extremely poor bonding performance, no adhesion, low elongation at break, and high MD thermal shrinkage, especially the extremely poor retention of elongation at break after PCT 48h; therefore, this conventional three-layer co-extruded PET photovoltaic packaging film on the market cannot be used directly as a replacement for the packaging material for photovoltaic modules of Examples 1-3.

[0061] The packaging materials for photovoltaic modules of Examples 1-3 (integrally molded photovoltaic packaging materials) have similar performances to conventional CPC photovoltaic back films on the market (as shown in Comparative Example 4); however, the packaging materials for photovoltaic modules of Examples 1-3 do not need to add coating and other processes as in Comparative Example 4. Therefore, the packaging materials for photovoltaic modules of Examples 1-3 have fewer processes, which can save costs and have excellent comprehensive performance (such as low ultraviolet light transmittance, high tensile strength, high elongation at break, low MD heat shrinkage, good bonding performance with EVA film, good bonding performance with silica gel, low resistance to ultraviolet and heat aging and yellowing, and high retention rate of elongation at break after PCT48h), which can more effectively improve the service life of photovoltaic modules.

[0062] In summary, embodiments 1-3 of the present invention provide a packaging material for photovoltaic modules that has a conventional three-layer sandwich structure, has excellent comprehensive performance, is green and environmentally friendly, can complete the production of packaging materials for different product types online (the melt flow ratio of each layer can be adjusted online to achieve production switching of packaging materials for different product types), and can meet a single production process (through a three-layer co-extrusion device, intra-film compounding and online double-drawing one-time forming, without the need for coating and / or adhesive compounding of other materials and other processes), and can be cut and shipped online; the packaging material for photovoltaic modules is applied to the back of a single-glass photovoltaic module (specifically, the adhesive layer of the packaging material is bonded to the back of the photovoltaic module through a packaging film such as EVA), which can effectively improve the service life of the photovoltaic module.

[0063] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0064] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a packaging material for a photovoltaic module, characterized in that: The method comprises the following preparation steps: Step 1: Preparation of functional masterbatch: The anti-hydrolysis agent and the modified polyester chips are uniformly mixed in a mass ratio of 7-20:100, and then melt-extruded and granulated to obtain an anti-hydrolysis masterbatch; The ultraviolet absorber and the modified polyester chips are uniformly mixed in a mass ratio of 5-25:100, and then melt-extruded and granulated to obtain ultraviolet absorbing masterbatch; The light stabilizer and the modified polyester chips are uniformly mixed in a mass ratio of 1-3:100, and then melt-extruded and granulated to obtain a light-stabilized masterbatch; Step 2: Preparation of functional layer masterbatch: By weight, 10-30 parts of anti-hydrolysis masterbatch, 5-20 parts of ultraviolet absorption masterbatch, 5-10 parts of light-stabilizing masterbatch and 185-230 parts of modified polyester chips are mixed evenly, and then melt-extruded and granulated to obtain weather-resistant layer masterbatch; 70-80 parts of modified polyester chips and 20-30 parts of connecting particles are mixed evenly, and then melt-extruded and granulated to obtain a core layer masterbatch; 20-60 parts of adhesive, 20-50 parts of modified polyester chips and 2-10 parts of anti-hydrolysis masterbatch are mixed evenly, melt-extruded and granulated to obtain bonding layer masterbatch; Step 3, by weight, 100-175 parts of weather-resistant layer masterbatch, 200-300 parts of core layer masterbatch, and 50-70 parts of bonding layer masterbatch are respectively put into the A machine, B machine, and C machine of the co-extrusion equipment, and the masterbatch of each layer is melted and co-extruded in three layers, and cooled to obtain a cast sheet; Step 4: The casting sheet is subjected to biaxial stretching, shaping and cooling in sequence to obtain a packaging material for photovoltaic modules.

2. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: The modified polyester chips are acid-modified polyester chips, with a discharge temperature of 260-285°C, an intrinsic viscosity of 0.7-0.9 dL / g, a terminal carboxyl range of 20-30 mol / t, and a melting point in the range of 252-262°C; The anti-hydrolysis agent is at least one of monomeric carbodiimide, polycarbodiimide, and oxazoline-type compound; The ultraviolet absorber is at least one of a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, and a triazine type ultraviolet absorber; The light stabilizer is a hindered amine light stabilizer.

3. The method for preparing a packaging material for a photovoltaic module according to claim 2, characterized in that: The anti-hydrolysis agent is carbodiimide, the ultraviolet absorber is UV239 ultraviolet absorber, and the light stabilizer is BASF light stabilizer UV791.

4. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: In step 1, the preparation of the anti-hydrolysis masterbatch, the ultraviolet absorption masterbatch and the light-stabilizing masterbatch is carried out by uniformly mixing in a double-cone rotary mixer, the speed of the double-cone rotary mixer is controlled to be 8-12 rpm, and the mixing time is less than or equal to 1 hour.

5. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: The connecting particles are the following resin particles F534A, M545, M704, M603, P553A, P565, F502C, F535, ADMER™, BYNEL™2200, NUCREL™, Plexar PX3080, Plexar ® At least one of PX2250; The adhesive is the following olefin resin VESTOPLAST ® 206. VESTOPLAST ® 206 EPP、VESTOPLAST ® 308. VESTOPLAST ® 508.VESTOPLAST ® 608, VESTOPLAST ® 704、VESTOPLAST ® 750, VESTOPLAST ® 792. VESTOPLAST ® EP V2094、VESTOPLAST ® 828, VESTOPLAST ® 891、VESTOPLAST ® At least one of SR, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene.

6. The method for preparing a packaging material for a photovoltaic module according to claim 5, characterized in that: The connecting particles are resin particles F534A, and the bonding material is olefin resin VESTOPLAST ® 206.

7. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: In step 2, the preparation of the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch are all carried out in a double-cone rotary mixer for the uniform mixing operation, and the melt extrusion granulation operation is carried out by a twin-screw extruder, the extrusion temperature is 200-280°C, and the screw speed is 5-13rpm.

8. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: The step 3 specifically includes: putting the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch into the A machine, the B machine and the C machine of the co-extrusion equipment respectively, drying them at 150-170°C for 2-4h, adjusting the melt pump flow ratios of the A machine, the B machine and the C machine to 1-3:2-4:0.5-1 respectively, melt-mixing the weather-resistant layer masterbatch, the core layer masterbatch and the bonding layer masterbatch through the three single-screw extruders ABC respectively, extruding them through three-layer co-extrusion at 200-280°C, and rapidly cooling them through a 3-10°C chill roller to form a cast sheet.

9. The method for preparing a packaging material for a photovoltaic module according to claim 1, characterized in that: The step 4 specifically includes: asynchronously stretching the cast sheet, with a transverse stretching ratio of 1-3.5 times, a longitudinal stretching ratio of 1-3.5 times, a preheating time of 80-150s, a stretching temperature of 90-120°C, a shaping temperature of 200-230°C, a shaping time of 10-30s, and obtaining the packaging material for the photovoltaic module after extrusion with a cooling roller, cooling, pulling, trimming, and winding.

10. A packaging material for a photovoltaic module, characterized in that: It is prepared by the method for preparing a packaging material for a photovoltaic module according to any one of claims 1 to 9; The packaging material for photovoltaic modules is applied to the back of the photovoltaic modules, and comprises a weather-resistant layer, a core layer and a bonding layer formed by co-extrusion and double-drawing in one step. The upper and lower surfaces of the core layer are provided with the weather-resistant layer and the bonding layer respectively.

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