Encapsulant for photovoltaic modules and method of making same

Abstract

The present application relates to the technical field of sealant, in particular to a kind of encapsulating material for photovoltaic module and preparation method thereof.By percentage of weight, component includes: APAO 10-20%, polyisobutylene 10-20%, butyl rubber 2-8%, silane coupling agent 0.1-2%, antioxidant 0.1-4%, filler makes up the rest, the water vapor transmission rate of the encapsulating material under 38 DEG C, 90%RH is not higher than 0.02g / (m 2 ·24h).The encapsulating material for module provided by the present application has excellent weather resistance, air tightness and chemical stability, can effectively prevent the erosion of moisture and oxygen and the like to photovoltaic module, thereby improving the service life and power generation efficiency of module.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, specifically to an encapsulation material for photovoltaic modules and its preparation method. Background Technology

[0002] With the global energy crisis and escalating environmental pollution, solar energy, as a clean and renewable energy source, has garnered significant attention. Photovoltaic modules are the core of solar power systems, and their performance and quality directly impact power generation efficiency and lifespan. The selection of encapsulation materials is crucial. While commonly used materials such as EVA (ethylene-vinyl acetate copolymer) and POE (ethylene-α-olefin copolymer elastomer) meet basic requirements, they have shortcomings in weather resistance, adhesion, and aging resistance. EVA is prone to yellowing and degradation, affecting light transmittance and power generation efficiency; POE has poor adhesion, affecting structural stability. The materials also have poor aging resistance, impacting lifespan. Therefore, improving photovoltaic module encapsulation materials to enhance performance and reliability is a pressing issue in the photovoltaic manufacturing industry and is of great significance for promoting the development of solar energy.

[0003] Chinese invention patent CN106634653A relates to a photovoltaic module encapsulation film with three-dimensional thermally conductive channels, its preparation method, and the module itself. This invention provides a photovoltaic module encapsulation film with three-dimensional thermally conductive channels, comprising a polymeric main resin, which includes one-dimensional carbon nanotubes and / or two-dimensional graphene, and zero-dimensional thermally conductive particle fillers. The polymeric main resin is EVA, POE, or EPDM (ethylene propylene diene monomer rubber). This film can effectively and promptly transfer the heat generated by the solar module during power generation, reduce the module's operating temperature, increase the module's power generation, and reduce the module's power generation cost. However, POE has poor adhesion, affecting structural stability. Summary of the Invention

[0004] The first aspect of this invention provides an encapsulation material for photovoltaic modules, comprising, by weight percentage: 10-20% APAO (amorphous polyalphaolefin), 10-20% polyisobutylene, 2-8% butyl rubber, 0.1-2% silane coupling agent, 0.1-4% antioxidant, and filler to make up the balance. The butyl rubber has a water vapor transmission rate (GB / T 26253) of not more than 0.02 g / (m³) at 38°C and 90% RH. 2 •24h).

[0005] The filler includes at least one of the following: silica, calcium carbonate, talc, barium sulfate, bentonite, mica, carbon black, and molecular sieve.

[0006] Preferably, the filler includes calcium carbonate, talc, and carbon black, and the weight ratio of calcium carbonate, talc, and carbon black is 1:(0.4-0.6):(1-2).

[0007] The applicant's research found that the filler includes calcium carbonate, talc, and carbon black, and the weight ratio of calcium carbonate, talc, and carbon black is limited to 1:(0.4-0.6):(1-2), which can improve the hardness and shear strength of the sealant. Calcium carbonate particles play a supporting role in the adhesive, talc fills the tiny gaps in the adhesive and enhances the structural strength of the adhesive, and carbon black has a very high specific surface area and surface energy, which can form a strong interaction with APAO. At the same time, carbon black particles can act as "crosslinking points" to connect calcium carbonate and talc, and together they form a hard skeleton structure in the sealant.

[0008] Further research revealed that limiting the particle size of calcium carbonate to 60-100 nm, talc (including silane-modified talc), and carbon black to 60-150 nm can further improve the hardness of the sealant to 80 (Shore A), while maintaining a glass-to-glass shear strength of no less than 0.4 MPa, making it suitable for photovoltaic module encapsulation. The nanostructures of calcium carbonate and carbon black increase the specific surface area and activity of the fillers, allowing for tight packing within the sealant. However, the nanostructures are prone to agglomeration, affecting their dispersibility in the sealant. Silane-modified talc acts as a lubricant for the nanostructured talc and carbon black, while simultaneously forming a physical cross-linking network with APAO through hydrogen bonding.

[0009] Preferably, the weight ratio of calcium carbonate, talc, and carbon black is 1:(0.4-0.6):(1-1.4).

[0010] The APAO has a softening point of 150-175℃, a penetration of 12-20 dmm at 25℃, and a density of 0.8-0.94 g / cm³. 3 .

[0011] Preferably, the APAO has a softening point of 150-165℃, a penetration of 14-18 dmm at 25℃, and a density of 0.86-0.92 g / cm³. 3 .

[0012] APAO possesses excellent weather resistance and airtightness, but its adhesion to low surface energy and low surface substrates is relatively poor, and its aging resistance is insufficient. This application's research found that by compounding APAO, butyl rubber, and polyisobutylene, and limiting the weight ratio of APAO, butyl rubber, and polyisobutylene to (2-4):(1-1.5):4, the aging resistance of the sealant can be effectively improved, and the water vapor transmission rate (GB / T26253) at 38℃ and 90% RH is not higher than 0.02 g / (m²). 2(24h). This meets the requirements for photovoltaic module applications. The adhesive properties and low crystallinity of APAO may complement the stability and inertness of butyl rubber, while polyisobutylene acts as a tackifier, improving the wettability and penetration of the sealant onto the adhered materials, thus enhancing the bonding effect. Furthermore, van der Waals forces and hydrogen bonds occur between the molecules of APAO, butyl rubber, and polyisobutylene, effectively increasing the segmental density.

[0013] Generally, longer polymer chain segments result in better overall performance, but also greater resistance to dispersibility. This is especially true in this application, which involves a blend of three polymer compounds and up to four fillers, significantly limiting dispersibility. The applicant accidentally discovered that by limiting the Mooney viscosity of butyl rubber to 40-60, the viscosity-average molecular weight of polyisobutylene to 40,000-100,000, and the softening point of APAO to 150-175℃, the penetration at 25℃ to 12-20 dmm, and the density to 0.8-0.94 g / cm³, dispersibility can be improved. 3 The melt index of the sealant can be controlled at 20-25 g / 10 min (130℃ / 10 kg / 600 s), while the water vapor transmission rate (GB / T 26253) is as low as 0.01 g / (m²). 2 The 24h timeframe may have balanced the chain length and dispersion properties of the polymer compounds, thereby improving the structural stability of the system.

[0014] The weight ratio of APAO, butyl rubber, and polyisobutylene is (2-4):(1-1.5):4.

[0015] Preferably, the weight ratio of APAO, butyl rubber, and polyisobutylene is (2-4):1:4.

[0016] The butyl rubber has a Mooney viscosity of 40-60.

[0017] Preferably, the Mooney viscosity of the butyl rubber is 45-55.

[0018] The viscosity-average molecular weight of the polyisobutylene is 40,000-100,000.

[0019] Preferably, the viscosity-average molecular weight of the polyisobutylene is 40,000-85,000.

[0020] Preferably, the silane coupling agent comprises a mixture of vinylsilane and an inert support.

[0021] The antioxidants include antioxidant 1010 and antioxidant 168, and the weight ratio of antioxidant 1010 to antioxidant 168 is 1:(0.8-1.2).

[0022] The calcium carbonate has a particle size of 60-100 nm.

[0023] Preferably, the calcium carbonate has a particle size of 60-80 nm.

[0024] The talc powder includes silane-modified talc powder.

[0025] The carbon black has a particle size of 60-150 nm.

[0026] Preferably, the particle size of the carbon black is 80-130 nm.

[0027] The silica has a mesh size of 1000-3000 mesh.

[0028] Preferably, the silica has a mesh size of 1000-2000 mesh.

[0029] A second aspect of the present invention provides a method for preparing an encapsulation material for photovoltaic modules, comprising the following steps:

[0030] Step 1: Mix APAO, polyisobutylene, antioxidant, and calcium carbonate, talc, and carbon black from the filler until homogeneous to obtain a mixture;

[0031] Step 2: Add the remaining filler and silane coupling agent to the mixture, stir evenly, and press to obtain the encapsulation material.

[0032] The stirring temperature in step 1 is 150-190℃ and the stirring time is 0.5-1.5h. The stirring time in step 2 is 2-5h.

[0033] Preferably, the stirring temperature in step 1 is 150-170℃ and the stirring time is 0.5-1.5h, and the stirring time in step 2 is 2-4h.

[0034] Beneficial effects

[0035] 1. The fillers include calcium carbonate, talc, and carbon black, and the weight ratio of calcium carbonate, talc, and carbon black is limited to [specific ratio to be specified].

[0036] 1:(0.4-0.6):(1-2) can improve the hardness and shear strength of the sealant.

[0037] 2. The particle size of calcium carbonate is limited to 60-100nm, talc powder including silane-modified talc powder, and carbon black particle size is 60-150nm, which can further improve the hardness of the sealant to 80 (Shore A), while the glass-to-glass shear strength is not less than 0.4MPa.

[0038] 3. By compounding APAO, butyl rubber, and polyisobutylene, and limiting the weight ratio of APAO, butyl rubber, and polyisobutylene to (2-4):(1-1.5):4, the aging resistance of the sealant can be effectively improved, and

[0039] At 38℃ and 90% RH, the water vapor transmission rate (GB / T 26253) shall not exceed 0.02 g / (m²). 2 •24h).

[0040] To meet the application requirements of photovoltaic modules.

[0041] 4. By limiting the Mooney viscosity of butyl rubber to 40-60, the viscosity-average molecular weight of polyisobutylene to 40,000-100,000, and the softening point of APAO to 150-175℃, the penetration at 25℃ to 12-20 dmm, and the density to 0.8-0.94 g / cm³, the desired product is achieved. 3 The melt index of the sealant can be controlled at 20-25 g / 10 min (130℃).

[0042] / 10kg / 600s), while the water vapor transmission rate (GB / T 26253) is as low as 0.01g / (m 2 •24h).

[0043] 5. By employing a specific preparation process, the modified APAO can be uniformly dispersed in the encapsulation material to form a stable structure, thereby improving the structural stability and power generation efficiency of the photovoltaic module. Attached Figure Description

[0044] Figure 1 The morphology of the sample in Example 1 before PCT aging is shown.

[0045] Figure 2 The morphology of the sample from Example 1 after PCT aging for 500 hours is shown.

[0046] Figure 3 The morphology of Comparative Example 1 sample after PCT aging for 500 hours is shown. Detailed Implementation

[0047] Examples 1-5, Comparative Examples 1-4

[0048] A photovoltaic module encapsulation material, with its composition by weight percentage, is shown in Table 1:

[0049] Table 1

[0050]

[0051]

[0052] In Examples 1-5 and Comparative Examples 1-2, the preparation method of the encapsulation material for the photovoltaic module includes the following steps:

[0053] Step 1: Preheat the kneader to 170°C, mix APAO, methyl styrene resin, polyisobutylene, antioxidant, and calcium carbonate, talc and carbon black from the fillers, and stir at 170°C for 1 hour to obtain a mixture;

[0054] Step 2: Add the remaining components to the mixture, stir at 170°C for 3 hours, and then laminate at 150°C and 1.5 MPa to form a 1.5 mm thick encapsulation material.

[0055] In Comparative Examples 3-4, the preparation method of the encapsulation material used in the photovoltaic module includes the following steps:

[0056] Step 1: Preheat the kneader to 170°C, mix APAO, butyl rubber, polyisobutylene, antioxidant, and calcium carbonate, talc and carbon black from the fillers, and stir at 170°C for 1 hour to obtain a mixture;

[0057] Step 2: Add the remaining components to the mixture, stir at 170°C for 3 hours, and then laminate at 150°C and 1.5 MPa to form a 1.5 mm thick encapsulation material.

[0058] Performance testing methods and data

[0059] The encapsulation materials prepared in the examples and comparative examples were subjected to performance tests, and the test data are listed in Table 2. Comparative Examples 2-4 had excessively high water vapor permeability and were not subjected to PCT aging tests; these are marked with " / ".

[0060] PCT aging test: Add cobalt chloride reagent to photovoltaic glass bonded with butyl adhesive, and test it at 105℃ and 100% humidity for 500 hours, observing the color change of the test paper; add cobalt chloride reagent to another photovoltaic glass bonded with butyl adhesive, and test it at 85℃ and 85% humidity for 3000 hours, observing the color change; if there is no change in the color and surface morphology of the test paper, it is qualified; otherwise, it is unqualified.

[0061] Combination Figure 1 and Figure 2 It can be seen that the encapsulation material PCT prepared in Example 1 did not show any color change before and after aging. Figure 3 It can be seen that the encapsulation material PCT prepared in Comparative Example 1 showed obvious blistering on its surface after aging.

[0062] Performance test data

[0063] Table 2

[0064]

[0065]

Claims

1. An encapsulation material for photovoltaic modules, characterized in that, The components, by weight percentage, include: APAO 10-20%, polyisobutylene 10-20%, butyl rubber 2-8%, silane coupling agent 0.1-2%, antioxidant 0.1-4%, and filler to make up the balance. The butyl rubber has a water vapor transmission rate of no more than 0.02 g / (m²·24h) at 38℃ and 90%RH. The filler includes calcium carbonate, talc, and carbon black, with a weight ratio of 1:(0.4-0.6):(1-2). The weight ratio of APAO, butyl rubber, and polyisobutylene is (2-4):(1-1.5):

4. The silane coupling agent is a mixture of vinyl silane and an inert carrier.

2. The encapsulation material for photovoltaic modules according to claim 1, characterized in that, The butyl rubber has a Mooney viscosity of 40-60.

3. The encapsulation material for photovoltaic modules according to claim 1, characterized in that, The viscosity-average molecular weight of the polyisobutylene is 40,000-100,000.

4. The encapsulation material for photovoltaic modules according to claim 1, characterized in that, The talc powder includes silane-modified talc powder.

5. A method for preparing an encapsulation material for a photovoltaic module according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Mix APAO, polyisobutylene, butyl rubber, antioxidant, and fillers such as calcium carbonate, talc, and carbon black evenly to obtain a mixture; Step 2: Add the remaining components to the mixture, stir well, and press to obtain the encapsulation material.

6. The preparation method according to claim 5, characterized in that, The stirring temperature in step 1 is 150-190℃ and the stirring time is 0.5-1.5h. The stirring time in step 2 is 2-5h.

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