An encapsulation material for a photovoltaic module and a preparation method thereof

Abstract

The present invention relates to the technical field of photovoltaic encapsulation materials, and discloses an encapsulation material for photovoltaic modules and a preparation method thereof. The preparation method includes: first, preparing a hydrolysis-resistant masterbatch, an ultraviolet absorption masterbatch, and a light stabilizer masterbatch respectively; then, preparing a weather-resistant layer masterbatch (including specific weight parts of the hydrolysis-resistant masterbatch, ultraviolet absorption masterbatch, light stabilizer masterbatch, and modified polyester chips), a core layer masterbatch (including specific weight parts of modified polyester chips and connecting particles), and a bonding layer masterbatch (including specific weight parts of an adhesive, modified polyester chips, and hydrolysis-resistant masterbatch); however, specific weight parts of the weather-resistant layer masterbatch, core layer masterbatch, and bonding layer masterbatch are co-extruded in three layers, cooled, and then subjected to biaxial stretching, shaping, and cooling to obtain the encapsulation material for photovoltaic modules. The encapsulation material is formed by co-extrusion and double stretching in one step, without adding processes such as coating and / or compounding other materials, and has a simple process, low cost, excellent comprehensive performance, and environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic encapsulation materials, and particularly relates to an encapsulation material for photovoltaic modules and a preparation method thereof. Background Art

[0002] Traditional photovoltaic backsheets all use PET (polyethylene terephthalate) as the skeleton structure, and at the same time 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 back film formed by these 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, curing, slitting) to complete the production, so the production efficiency is not high and the labor cost consumption is huge.

[0003] Therefore, in order to improve the production efficiency of photovoltaic backsheets, the following existing photovoltaic encapsulation materials have been developed:

[0004] As shown in the publication number CN115625870A, a super-weather-resistant white polyester film and a preparation method thereof are disclosed. The super-weather-resistant white polyester film consists of a core layer and upper and lower surface layers. The raw materials of the core layer are tackifying polyester chips, hydrolysis-resistant masterbatch and white masterbatch with a mass ratio of 82-95:2-8:3-10. The raw materials of the upper and lower surface layers are tackifying polyester chips, white masterbatch and anti-ultraviolet masterbatch with a mass ratio of 55-84:15-35:1-10. The preparation method is as follows: the composition raw materials of the core layer and the composition raw materials of the surface layer are respectively mixed evenly and then melt-extruded. The melt is extruded through a three-layer coextrusion die head and then cast into a film by casting, and then biaxially stretched to obtain the 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 380 nm is ≤5%, the elongation at break after 72 hours of PCT is ≥40%, and △b after 200 kWh of ultraviolet irradiation is ≤3. However, due to the influence of the preparation method of the super-weather-resistant white polyester film shown in the publication number CN115625870A (for example, before the three-layer coextrusion, the composition raw materials of the surface layer and the composition raw materials of the core layer are not prepared as functional layer masterbatches in advance) and the raw material formula of each layer (for example, there are no particles with excellent connection effects between the surface layer and the core layer), the super-weather-resistant white polyester film still needs to be improved in terms of tensile strength, elongation at break, thermal shrinkage rate, ultraviolet and damp heat aging yellowing resistance performance, and bonding performance with EVA film or silica gel.

[0005] As shown in the publication number CN109473498A, a packaged integrated backplane and a preparation method thereof are disclosed. The packaged integrated backplane has good water resistance, good adhesion to solar cells, no photo-thermal aging phenomenon 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 such packaged integrated backplane has a polyolefin as the skeleton structure and a TPO (thermoplastic polyolefin) particle material layer as the connecting layer; moreover, before the three-layer co-extrusion, functional masterbatch and functional layer masterbatch are not 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 rate, yellowing performance of ultraviolet and damp heat aging resistance, and elongation at break retention rate after 48h of PCT. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a packaging material for photovoltaic modules and a preparation method thereof.

[0007] Based on this, the present invention discloses a preparation method of a packaging material for photovoltaic modules, including the following preparation steps:

[0008] Step 1, preparation of functional masterbatch:

[0009] After mixing an anti-hydrolysis agent and modified polyester chips in a mass ratio of 7-20:100 evenly, melt-extruding and pelletizing to obtain an anti-hydrolysis masterbatch;

[0010] After mixing an ultraviolet absorber and modified polyester chips in a mass ratio of 5-25:100 evenly, melt-extruding and pelletizing to obtain an ultraviolet absorption masterbatch;

[0011] After mixing a light stabilizer and modified polyester chips in a mass ratio of 1-3:100 evenly, melt-extruding and pelletizing to obtain a light stability masterbatch;

[0012] Step 2, preparation of functional layer masterbatch:

[0013] By weight, mixing 10-30 parts of anti-hydrolysis masterbatch, 5-20 parts of ultraviolet absorption masterbatch, 5-10 parts of light stability masterbatch and 185-230 parts of modified polyester chips evenly, and then melt-extruding and pelletizing to obtain a weather-resistant layer masterbatch;

[0014] By weight, mixing 70-80 parts of modified polyester chips and 20-30 parts of connecting particles (particles that can play a bonding role) evenly, and then melt-extruding and pelletizing to obtain a core layer masterbatch;

[0015] By weight, mixing 20-60 parts of adhesive, 20-50 parts of modified polyester chips and 2-10 parts of anti-hydrolysis masterbatch evenly, and then melt-extruding and pelletizing to obtain a bonding layer masterbatch;

[0016] Step 3: Weighing 100 - 175 parts by weight of weather - resistant masterbatch, 200 - 300 parts of core - layer masterbatch, and 50 - 70 parts of adhesive - layer masterbatch respectively, and putting them into machines A, B, and C of the co - extrusion equipment. The masterbatches of each layer are melt - co - extruded and cooled to obtain a cast sheet.

[0017] Step 4: After the cast sheet is subjected to biaxial stretching, shaping, and cooling in sequence, an encapsulation material for photovoltaic modules is obtained.

[0018] Preferably, the modified polyester chip is an acid - modified polyester chip, with an output temperature of 260 - 285 °C, an intrinsic viscosity of 0.7 - 0.9 dL / g, an end - carboxyl group range of 20 - 30 mol / t, and a melting point in the range of 252 - 262 °C.

[0019] Preferably, the anti - hydrolysis agent is at least one of monomeric carbodiimide, polycarbodiimide, and oxazoline - type compounds; the anti - hydrolysis agent is preferably carbodiimide.

[0020] Preferably, the ultraviolet absorber is at least one of benzophenone - type ultraviolet absorbers, benzotriazole - type ultraviolet absorbers, and triazine - type ultraviolet absorbers; the ultraviolet absorber is preferably UV239 ultraviolet absorber.

[0021] The light stabilizer is a hindered - amine light stabilizer; the light stabilizer is preferably BASF light stabilizer UV791.

[0022] Preferably, in step 1, the preparation of the anti - hydrolysis masterbatch, ultraviolet - absorption masterbatch, and light - stabilization masterbatch is all carried out in a double - cone rotary mixer for the operation of mixing evenly. The rotation speed of the double - cone rotary mixer is controlled at 8 - 12 rpm, and the mixing time is less than or equal to 1 h.

[0023] Preferably, the connecting particles are at least one of the following resin particles: F534A, M545, M704, M603, P553A, P565, F502C, F535, ADMER™, BYNEL™2200, NUCREL™, Plexar PX3080, Plexar ® PX2250; the connecting particles are preferably resin particle F534A, and its manufacturer is Mitsubishi Chemical Functional Plastics (China) Co., Ltd. Among them, the manufacturers of the above F, M, and P series resins are Mitsubishi Chemical Functional Plastics (China) Co., Ltd.

[0024] 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 ® SR, at least one of low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene; the adhesive is preferably the olefin resin VESTOPLAST ® 206. Among them, the Vestoplast series is the olefin resin of Evonik Specialty Chemicals (Shanghai) Co., Ltd.

[0025] Preferably, in step 2, the preparation of the weather-resistant layer masterbatch, the core layer masterbatch and the adhesive layer masterbatch is carried out in a double-cone rotary mixer for the operation of mixing evenly, and the operation of melt extrusion granulation is carried out through a twin-screw extruder. The extrusion temperature is 200 - 280 °C, and the screw speed is 5 - 13 rpm.

[0026] Preferably, step 3 specifically includes: putting the weather-resistant layer masterbatch, the core layer masterbatch, and the adhesive layer masterbatch into machines A, B, and C of the co-extrusion equipment respectively. After drying at 150 - 170 °C for 2 - 4 h, adjust the melt pump flow ratios of machines A, B, and C to 1 - 3:2 - 4:0.5 - 1 respectively. After the weather-resistant layer masterbatch, the core layer masterbatch, and the adhesive layer masterbatch are melted and mixed by the three single-screw extruders ABC respectively, they are co-extruded in three layers at 200 - 280 °C and rapidly cooled by a quench roll at 3 - 10 °C to form a cast sheet.

[0027] In step 3, by online adjusting the melt pump flow of machines A, B, and C, the production switching of encapsulation materials of different product types can be realized, and encapsulation materials of different product types can be directly processed to meet the different requirements for encapsulation materials in different application scenarios.

[0028] Polyester can form crystals within the range between the melting point and the glass transition temperature. Therefore, the main function of the quench roll is to form a transparent amorphous structure of the encapsulation material by rapidly cooling the melt.

[0029] Preferably, the step 4 specifically includes: performing asynchronous stretching on the cast film, with a transverse stretching ratio of 1 - 3.5 times, a longitudinal stretching ratio of 1 - 3.5 times, a preheating time of 80 - 150 s, a stretching temperature of 90 - 120 °C, a shaping temperature of 200 - 230 °C, and a shaping time of 10 - 30 s. After extrusion, cooling, traction, edge trimming, and winding by a cooling roller, the encapsulation material for the photovoltaic module is obtained.

[0030] The present invention also discloses an encapsulation material for a photovoltaic module, which is prepared by using the preparation method of an encapsulation material for a photovoltaic module described above in the present invention content;

[0031] The encapsulation material for the photovoltaic module is applied to the back of a photovoltaic module (especially a single - glass photovoltaic module), and it includes a weather - resistant layer (made of a weather - resistant layer masterbatch), a core layer (made of the above - mentioned core layer masterbatch), and an adhesive layer (made of the above - mentioned adhesive layer masterbatch) formed by co - extrusion and double - stretching in one step. The weather - resistant layer and the adhesive layer are respectively provided on the upper and lower surfaces of the core layer.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] 1. The encapsulation material for the photovoltaic module of the present invention is formed by in - film compounding and online double - stretching in one step through a three - layer co - extrusion device. Subsequently, there is no need to go through processes such as coating a coating and / or compounding other materials with an adhesive. It does not use adhesives and does not need to bond a fluorocarbon coating, without VOC emissions, greatly saving energy consumption and material costs. The processing cost is low, continuous production can be achieved, no separate curing is required, the processing process is simple, and recycling can be realized.

[0034] 2. Compared with the conventional three-layer coextruded PET photovoltaic encapsulation film on the market, for the encapsulation material for photovoltaic modules prepared by the present invention, a quantitative hydrolysis inhibitor, ultraviolet absorber, and light stabilizer are first mixed and melt-extruded with modified polyester chips to prepare a hydrolysis-resistant masterbatch, an ultraviolet-absorbing masterbatch, and a light-stabilizing masterbatch. Then, on the basis of the weather-resistant layer masterbatch composed of the above raw materials in the above weight ratio, the core layer masterbatch composed of the above raw materials in the above weight ratio is used in combination, and the adhesive layer masterbatch composed of the above raw materials in the above weight ratio is used in combination. Each layer of masterbatch is formed by coextrusion and double drawing in one step. Therefore, the encapsulation material has few structural defects, has a high retention rate of elongation at break during long-term aging tests (ultraviolet, ultraviolet damp heat, pressure cooking), has a small yellowing of ultraviolet and damp heat aging resistance, and at the same time, the encapsulation material has excellent tensile strength and elongation at break, and also has a low ultraviolet light transmittance and a low MD (longitudinal) thermal shrinkage rate. Moreover, the core layer made of the above core layer masterbatch is used as the intermediate layer, so that the weather-resistant layer and the adhesive layer are more closely connected and no delamination phenomenon will occur. In combination with the above adhesive layer, the bonding performance of the encapsulation material to different adhesive films (such as EVA adhesive film, silicone) can be improved without using a coating or adhesive, thereby improving the peel force and having a universal adhesiveness. Therefore, when the encapsulation material is applied to the back of a photovoltaic module (especially a single-glass photovoltaic module), the service life of the photovoltaic module can be effectively improved. Detailed Embodiments

[0035] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0036] In the following examples and comparative examples, the modified polyester chips are acid-modified polyester chips, the discharge temperature is 270 °C, the intrinsic viscosity is 0.8 dL / g, the range of terminal carboxyl groups is 28 mol / t, and the melting point is within the range of 261 °C.

[0037] Example 1

[0038] A preparation method of an encapsulation material for a photovoltaic module in this example includes the following preparation steps:

[0039] Step 1. Preparation of functional masterbatch:

[0040] Preparation of hydrolysis-resistant masterbatch: 10 parts (by weight, the same below) of a hydrolysis inhibitor and 135 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer, the rotation speed of the double-cone rotary mixer is controlled to be 10 rpm, and the mixing time is 0.5 h. The mixed particles are melt-extruded and granulated through a twin-screw extruder to obtain a hydrolysis-resistant masterbatch. Among them, the hydrolysis inhibitor is carbodiimide.

[0041] Preparation of ultraviolet absorption masterbatch: 5 parts of ultraviolet absorber and 100 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer. The rotation speed of the double-cone rotary mixer is controlled at 8 rpm, and the mixing time is 1 h. The mixed particles are melt-extruded and granulated through a twin-screw extruder to obtain the ultraviolet absorption masterbatch. Among them, the ultraviolet absorber is UV239 ultraviolet absorber.

[0042] Preparation of light stabilizer masterbatch: 2 parts of light stabilizer and 100 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer. The rotation speed of the double-cone rotary mixer is controlled at 8 rpm, and the mixing time is 1 h. The mixed particles are melt-extruded and granulated through a twin-screw extruder to obtain the light stabilizer masterbatch. Among them, the light stabilizer is BASF light stabilizer UV791.

[0043] Step 2, Preparation of functional layer masterbatch:

[0044] Preparation of weather-resistant layer masterbatch: 20 parts of hydrolysis-resistant masterbatch, 8 parts of ultraviolet absorption masterbatch, 9 parts of light stabilizer 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 13 rpm to obtain the weather-resistant layer masterbatch.

[0045] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles 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 13 rpm to obtain the core layer masterbatch. Among them, the connecting particles are resin particles F534A.

[0046] Preparation of adhesive layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of hydrolysis-resistant masterbatch 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 12 rpm to obtain the adhesive layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0047] Step 3, Put 175 parts of weather-resistant layer masterbatch, 200 parts of core layer masterbatch and 50 parts of adhesive layer masterbatch into machine A, machine B and machine C of the co-extrusion equipment respectively. After drying at 160 °C for 4 h, adjust the melt pump flow ratio of machine A, machine B and machine C to 1:1.03:0.5 respectively. The weather-resistant layer masterbatch, core layer masterbatch and adhesive layer masterbatch are melt-mixed through the three single-screw extruders of ABC respectively, and then co-extruded at 265 °C through three layers, and rapidly cooled by a 5 °C quench roll to make a cast sheet.

[0048] Step 4: Asynchronous stretching of the cast film, with the transverse stretching ratio and the longitudinal stretching ratio both being 3 times, the preheating time being 90 s, the stretching temperature being 95 °C, the shaping temperature being 220 °C, and the shaping time being 10 s. After extrusion, cooling, traction, trimming, and winding by a cooling roller, a packaging material for a photovoltaic module of this embodiment is obtained.

[0049] A packaging material for a photovoltaic module of this embodiment includes a weather-resistant layer, a core layer, and an adhesive layer stacked in sequence. The weather-resistant layer and the adhesive layer are both connected through the core layer; and the masterbatch for the weather-resistant layer (for preparing the weather-resistant layer), the masterbatch for the core layer (for preparing the core layer), and the masterbatch for the adhesive layer (for preparing the adhesive layer) are respectively co-extruded into a cast film through in-mold compounding by three single-screw extruders and then directly stretched by a double-stretching process. Among them, the total thickness of the packaging material is 285 μm, and the thickness ratio of the weather-resistant layer, the core layer, and the adhesive layer is 1:2:1.

[0050] Example 2

[0051] A preparation method of a packaging material for a photovoltaic module of this embodiment includes the following preparation steps:

[0052] Step 1: Preparation of functional masterbatch:

[0053] Preparation of hydrolysis-resistant masterbatch: Mix 15 parts (by weight, the same below) of a hydrolysis-resistant agent and 120 parts of modified polyester chips evenly in a double-cone rotary mixer. Control the rotation speed of the double-cone rotary mixer to be 12 rpm and the mixing time to be 0.8 h. Extrude and pelletize the mixed particles through a twin-screw extruder to obtain a hydrolysis-resistant masterbatch. Among them, the hydrolysis-resistant agent is carbodiimide.

[0054] Preparation of ultraviolet absorption masterbatch: Mix 15 parts of an ultraviolet absorber and 100 parts of modified polyester chips evenly in a double-cone rotary mixer. Control the rotation speed of the double-cone rotary mixer to be 9 rpm and the mixing time to be 1 h. Extrude and pelletize the mixed particles through a twin-screw extruder to obtain an ultraviolet absorption masterbatch. Among them, the ultraviolet absorber is UV239 ultraviolet absorber.

[0055] Preparation of light-stabilizing masterbatch: Mix 2 parts of a light stabilizer and 100 parts of modified polyester chips evenly in a double-cone rotary mixer. Control the rotation speed of the double-cone rotary mixer to be 8 rpm and the mixing time to be 1 h. Extrude and pelletize the mixed particles through a twin-screw extruder to obtain a light-stabilizing masterbatch. Among them, the light stabilizer is BASF light stabilizer UV791.

[0056] Step 2: Preparation of functional layer masterbatch:

[0057] Preparation of weather-resistant layer masterbatch: 15 parts of hydrolysis-resistant masterbatch, 10 parts of UV absorber masterbatch, 7 parts of light stabilizer masterbatch and 198 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer, and then melt-extruded and pelletized through a twin-screw extruder. The extrusion temperature is 265 °C, and the screw speed is 12 rpm to obtain the weather-resistant layer masterbatch.

[0058] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles are mixed evenly in a double-cone rotary mixer, and then melt-extruded and pelletized through a twin-screw extruder. The extrusion temperature is 275 °C, and the screw speed is 13 rpm to obtain the core layer masterbatch. Among them, the connecting particles are resin particles F534A.

[0059] Preparation of adhesive layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of hydrolysis-resistant masterbatch are mixed evenly in a double-cone rotary mixer, and then melt-extruded and pelletized through a twin-screw extruder. The extrusion temperature is 275 °C, and the screw speed is 12 rpm to obtain the adhesive layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0060] Step 3: Put 150 parts of weather-resistant layer masterbatch, 300 parts of core layer masterbatch and 70 parts of adhesive layer masterbatch into machines A, B and C of the co-extrusion equipment respectively. After drying at 170 °C for 3 h, adjust the melt pump flow ratios of machines A, B and C to 1:1.5:0.5 respectively. The weather-resistant layer masterbatch, core layer masterbatch and adhesive layer masterbatch are melt-mixed through the three single-screw extruders A, B and C respectively, and then co-extruded at 270 °C through three layers, and rapidly cooled by a 3 °C chill roll to form a cast sheet.

[0061] 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 s, a stretching temperature of 100 °C, a shaping temperature of 220 °C, and a shaping time of 15 s. After being extruded, cooled, tractioned, trimmed and wound by a cooling roll, a packaging material for a photovoltaic module of this embodiment is obtained.

[0062] For a packaging material for a photovoltaic module of this embodiment, its specific structure refers to Embodiment 1, so it will not be elaborated here.

[0063] Embodiment 3

[0064] A preparation method of a packaging material for a photovoltaic module of this embodiment includes the following preparation steps:

[0065] Step 1: Preparation of functional masterbatch:

[0066] Preparation of hydrolysis-resistant masterbatch: 30 parts (by weight, the same below) of hydrolysis-resistant agent and 150 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer. The rotation speed of the double-cone rotary mixer is controlled at 10 rpm, and the mixing time is 0.5 h. The mixed particles are melt-extruded and pelletized through a twin-screw extruder to obtain the hydrolysis-resistant masterbatch. Among them, the hydrolysis-resistant agent is carbodiimide.

[0067] Preparation of ultraviolet absorption masterbatch: 20 parts of ultraviolet absorber and 80 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer. The rotation speed of the double-cone rotary mixer is controlled at 12 rpm, and the mixing time is 1 h. The mixed particles are melt-extruded and pelletized through a twin-screw extruder to obtain the ultraviolet absorption masterbatch. Among them, the ultraviolet absorber is UV239 ultraviolet absorber.

[0068] Preparation of light-stabilizing masterbatch: 2 parts of light stabilizer and 100 parts of modified polyester chips are mixed evenly in a double-cone rotary mixer. The rotation speed of the double-cone rotary mixer is controlled at 8 rpm, and the mixing time is 1 h. The mixed particles are melt-extruded and pelletized through a twin-screw extruder to obtain the light-stabilizing masterbatch. Among them, the light stabilizer is BASF light stabilizer UV791.

[0069] Step 2. Preparation of functional layer masterbatch:

[0070] Preparation of weather-resistant layer masterbatch: 12 parts of hydrolysis-resistant masterbatch, 15 parts of ultraviolet 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 pelletized through a twin-screw extruder. The extrusion temperature is 275 °C, and the screw rotation speed is 12 rpm to obtain the weather-resistant layer masterbatch.

[0071] Preparation of core layer masterbatch: 75 parts of modified polyester chips and 25 parts of connecting particles are mixed evenly in a double-cone rotary mixer, and then melt-extruded and pelletized through a twin-screw extruder. The extrusion temperature is 275 °C, and the screw rotation speed is 13 rpm to obtain the core layer masterbatch. Among them, the connecting particles are resin particles F534A.

[0072] Preparation of adhesive layer masterbatch: 57 parts of high-performance adhesive, 40 parts of modified polyester chips and 3 parts of hydrolysis-resistant masterbatch are mixed evenly in a double-cone rotary mixer, and then melt-extruded and pelletized through a twin-screw extruder. The extrusion temperature is 275 °C, and the screw rotation speed is 12 rpm to obtain the adhesive layer masterbatch. Among them, the high-performance adhesive is olefin resin VESTOPLAST ® 206.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] Comparative Example 1

[0077] 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:

[0078] 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.

[0079] Comparative Example 2

[0080] 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:

[0081] 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.

[0082] Comparative Example 3

[0083] A kind of encapsulation material for photovoltaic modules in this comparative example directly uses a conventional three-layer coextruded PET photovoltaic encapsulation film on the market. This three-layer coextruded PET photovoltaic encapsulation film is: Jiangsu Yuxing Film Technology Co., Ltd. (CY25HT (GU) anti-ultraviolet transparent polyester film for solar backsheet); the thickness ratio of layer A: layer B: layer A is 1:2:1, layer A is the weather-resistant layer, layer B is the intermediate layer, and the total thickness of the three layers is 285 μm.

[0084] Comparative Example 4

[0085] A kind of encapsulation material for photovoltaic modules in this comparative example directly uses a conventional CPC photovoltaic backsheet on the market (which is a composite material with polycarbonate as the base material and a fluorocarbon coating on the surface). This CPC photovoltaic backsheet is: Zhonglai Photovoltaic FFCJW3010P, which has a 20-μm weather-resistant coating, a 275-μm PET base material, and a 10-μm inner coating stacked in sequence.

[0086] Performance test

[0087] Perform performance tests on the encapsulation materials for photovoltaic modules in Examples 1-3 and Comparative Examples 1-4 respectively. The test results are shown in Table 1 below. In Table 1, UV+DH30 (kWh / m 2 ) is a combined aging test, and its test conditions are: under DH conditions (temperature 85 °C, humidity 85%), the ultraviolet irradiation dose reaches 30 kWh / m 2 .

[0088] Table 1

[0089]

[0090] As can be seen from Table 1 above:

[0091] The MD thermal shrinkage rate of the encapsulation materials for photovoltaic modules in Examples 1-3 is lower than that in Comparative Example 1, and the MD thermal shrinkage rate of the encapsulation materials for photovoltaic modules in Comparative Example 1 > 0.6%; therefore, in the process of preparing the encapsulation materials for photovoltaic modules in Comparative Example 1, stretching and heat setting processes need to be carried out additionally, otherwise it will lead to poor production of photovoltaic modules. It should be noted that currently, for photovoltaic encapsulation materials or photovoltaic backsheets, the MD thermal shrinkage rate is generally required to be less than 0.6%, which is for the latest photovoltaic modules. For conventional photovoltaic modules, the gap between the cells is large, and a slightly larger MD thermal shrinkage rate is okay and will not cause shunting between adjacent two cells. However, nowadays, photovoltaic modules pursue higher efficiency and power generation, so the gap between the cells is required to be very small, usually 1-2 mm (the original gap between the cells was 4-5 mm); when the gap between the cells is small, when the photovoltaic encapsulation materials shrink slightly during lamination, it will cause the movement of the cells, resulting in the cells being stacked on top of each other (i.e., shunting), and further leading to poor production of a large number of photovoltaic modules.

[0092] If directly using a weather-resistant layer + adhesive layer or a weather-resistant layer + modified polyester chip particle layer without connecting particles + adhesive layer (as shown in Comparative Example 1), the adhesive layer and other layers are prone to delamination and it is difficult to be formed into one body by coextrusion molding.

[0093] Compared with Comparative Example 1 (in Comparative Example 1, the core layer masterbatch of Example 1 was directly replaced with modified polyester chip particles), the MD thermal shrinkage rates of the encapsulation materials for photovoltaic modules in Examples 1-3 are all < 0.6%. At the same time, the retention rates of the elongation at break after PCT 48h treatment of the encapsulation materials for photovoltaic modules in Examples 1-3 are all greater than 40%; moreover, compared with Comparative Examples 1-2 (in Comparative Example 2, the adhesive layer masterbatch of Example 1 was directly replaced with a hydrolysis-resistant masterbatch), the encapsulation materials for photovoltaic modules in Examples 1-3 also have greater tensile strength and elongation at break, smaller MD thermal shrinkage rate and more excellent adhesive properties (the encapsulation materials for photovoltaic modules in Examples 1-3 have better adhesive strength for various types of adhesive films and silicones and have a wide range of adhesiveness). Therefore, the encapsulation materials for photovoltaic modules in Examples 1-3 can more effectively improve the service life of photovoltaic modules.

[0094] Compared with Examples 1-3, the conventional three-layer coextruded PET photovoltaic encapsulation film on the market currently (as shown in Comparative Example 3) has a large ultraviolet light transmittance, large yellowing during ultraviolet and damp heat aging resistance, extremely poor adhesive properties, no adhesive force, low elongation at break, large MD thermal shrinkage rate, especially extremely poor retention rate of elongation at break after PCT 48h; therefore, this conventional three-layer coextruded PET photovoltaic encapsulation film on the market cannot directly replace the encapsulation materials for photovoltaic modules in Examples 1-3 for use.

[0095] The encapsulation materials for photovoltaic modules in Examples 1-3 (integrally formed photovoltaic encapsulation materials) have similar properties to the conventional CPC photovoltaic backsheets on the market (as shown in Comparative Example 4). However, the encapsulation materials for photovoltaic modules in Examples 1-3 do not require additional processes such as coating as in Comparative Example 4. Therefore, the encapsulation materials for photovoltaic modules in Examples 1-3 have fewer processes, can save costs, and have excellent comprehensive properties (such as low ultraviolet light transmittance, high tensile strength, high elongation at break, low MD heat shrinkage rate, good adhesion to EVA film, good adhesion to silicone, small yellowing during ultraviolet and damp heat aging, and large elongation at break retention rate after 48h of PCT), which can more effectively improve the service life of photovoltaic modules.

[0096] In summary, the encapsulation materials for photovoltaic modules provided in Examples 1-3 of the present invention have both a conventional three-layer sandwich structure, excellent comprehensive properties, are green and environmentally friendly, can complete the production of encapsulation materials of different product types online (the production switch of encapsulation materials of different product types can be realized by adjusting the melt flow ratio of each layer online), and can meet a single production process (formed in one step by in-membrane composite and online double stretching through a three-layer coextrusion device, without going through processes such as coating and / or compounding other materials with adhesives), and are cut and shipped online; when applied to the back of a single-glass photovoltaic module (specifically, the adhesive layer of the encapsulation material is bonded to the back of the photovoltaic module through an encapsulation adhesive film such as EVA), it can effectively improve the service life of the photovoltaic module.

[0097] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

[0098] The technical solutions provided by the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A preparation method of an encapsulation material for a photovoltaic module, characterized in that, It includes the following preparation steps: Step 1: Preparation of functional masterbatch: After uniformly mixing a hydrolysis-resistant agent and a modified polyester chip in a mass ratio of 7 - 20:100, melt extrusion granulation is carried out to obtain a hydrolysis-resistant masterbatch; After uniformly mixing an ultraviolet absorber and a modified polyester chip in a mass ratio of 5 - 25:100, melt extrusion granulation is carried out to obtain an ultraviolet absorption masterbatch; After uniformly mixing a light stabilizer and a modified polyester chip in a mass ratio of 1 - 3:100, melt extrusion granulation is carried out to obtain a light stability masterbatch; Step 2: Preparation of functional layer masterbatch: By weight, 10 - 30 parts of the hydrolysis-resistant masterbatch, 5 - 20 parts of the ultraviolet absorption masterbatch, 5 - 10 parts of the light stability masterbatch and 185 - 230 parts of the modified polyester chip are uniformly mixed and then melt extrusion granulation is carried out to obtain a weather-resistant layer masterbatch; 70 - 80 parts of the modified polyester chip and 20 - 30 parts of connecting particles are uniformly mixed and then melt extrusion granulation is carried out to obtain a core layer masterbatch; 20 - 60 parts of an adhesive, 20 - 50 parts of the modified polyester chip and 2 - 10 parts of the hydrolysis-resistant masterbatch are uniformly mixed and then melt extrusion granulation is carried out to obtain an adhesive layer masterbatch; Step 3: By weight, 100 - 175 parts of the weather-resistant layer masterbatch, 200 - 300 parts of the core layer masterbatch and 50 - 70 parts of the adhesive layer masterbatch are respectively put into machines A, B, and C of a co-extrusion device, and the masterbatches of each layer are melt co-extruded in three layers and cooled to obtain a cast sheet; The cast sheet is successively subjected to biaxial stretching, shaping, and cooling to obtain an encapsulation material for a photovoltaic module; The connecting particles are at least one of the following resin particles: F534A, M545, M704, M603, P553A, P565, F502C, F535, ADMER™, BYNEL™ 2200, NUCREL™, Plexar PX3080, Plexar ® 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; The modified polyester chip is an acid-modified polyester chip, its discharging temperature is 260 - 285°C, the intrinsic viscosity is 0.7 - 0.9 dL / g, the end carboxyl group range is 20 - 30 mol / t, and the melting point is in the range of 252 - 262°C.

2. The preparation method of an encapsulation material for a photovoltaic module according to claim 1, characterized in that, The hydrolysis-resistant agent is at least one of monomeric carbodiimide, polycarbodiimide, and oxazoline-type compounds; The ultraviolet absorber is at least one of benzophenone-type ultraviolet absorbers, benzotriazole-type ultraviolet absorbers, and triazine-type ultraviolet absorbers; The light stabilizer is a hindered amine-type light stabilizer.

3. The preparation method of an encapsulation material for a photovoltaic module according to claim 2, wherein, The hydrolysis-resistant agent is carbodiimide, the ultraviolet absorber is UV239 ultraviolet absorber, and the light stabilizer is BASF light stabilizer UV791.

4. The preparation method of a packaging material for a photovoltaic module according to claim 1, characterized in that, In Step 1, for the preparation of the hydrolysis-resistant masterbatch, ultraviolet absorption masterbatch, and light stability masterbatch, the operation of uniformly mixing is carried out in a double-cone rotary mixer, the rotation speed of the double-cone rotary mixer is controlled at 8 - 12 rpm, and the mixing time is less than or equal to 1 h.

5. The preparation method of a packaging material for a photovoltaic module according to claim 1, wherein, The connecting particles are resin particles F534A, and the binder is olefin resin VESTOPLAST ® 206 6. The preparation method of an encapsulation material for a photovoltaic module according to claim 1, characterized in that, In Step 2, for the preparation of the weather-resistant layer masterbatch, core layer masterbatch, and adhesive layer masterbatch, the operation of uniformly mixing is carried out in a double-cone rotary mixer, and the operation of melt extrusion granulation is carried out through a twin-screw extruder, the extrusion temperature is 200 - 280°C, and the screw rotation speed is 5 - 13 rpm.

7. The preparation method of an encapsulation 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.

8. The preparation method of an encapsulation material for a photovoltaic module according to claim 1, wherein, 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.

9. An encapsulation 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 8; 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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