POE packaging material for photovoltaic module and preparation method of POE packaging material

Abstract

The invention discloses a POE (Polyolefin Elastomer) packaging material for a photovoltaic module and a preparation method of the POE packaging material. The POE packaging material for the photovoltaic module comprises the following raw materials: POE, silane modified ethylene propylene diene monomer and a cross-linking agent, pOE and silane modified ethylene propylene diene monomer are mixed, melt extrusion and film casting are carried out, and then rolling is carried out, so that the POE / silane modified ethylene propylene diene monomer composite material is obtained. The POE packaging material provided by the invention has strong adhesion to a glass substrate, and has the advantages of high transparency, high strength, high viscosity and long-term durability.

Description

Technical Field

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

[0002] In order to achieve a photovoltaic (PV) module life of more than 20 years, it is imperative to select a high-quality encapsulant (also known as encapsulant) with long-term durability. It not only acts as an adhesive or sealant between the top glass and the crystalline silicon cells, but also protects the electrical components from corrosive environmental factors, thereby preventing PV module degradation such as delamination, corrosion, and discoloration.

[0003] Due to the high requirements of encapsulation materials, only a few polymer materials can be used as encapsulants. The most popular polymer encapsulation materials include ethylene vinyl acetate (EVA), silicone, polyvinyl butyral (PVB), ionomer, thermoplastic polyolefin (TPO), and polyolefin elastomer (POE).

[0004] Among them, EVA has been widely used as an encapsulation material for more than 30 years due to its low cost, high flexibility and good light transmittance. However, there are still some problems to be solved in the photovoltaic encapsulation of EVA films, because EVA can induce the formation of volatile organic compounds (VOCs) during the cross-linking process, which can accelerate the degradation of the sealant used for field operation in photovoltaic modules. In addition, its water absorption produces and accelerates acetic acid by chemically reacting with the acetic acid part of the EVA skeleton, thereby accelerating the failure of photovoltaic modules. Therefore, alternative polymers should be sought to replace EVA.

[0005] Compared with EVA, polyolefin elastomer (POE) has lower potential induced degradation (PID). Therefore, POE encapsulant will provide huge market prospects in the next decade. However, since POE is a non-polar polymer obtained by copolymerizing ethylene and advanced α-olefins using metallocene catalysts, and glass is a polar inorganic material with a smooth surface, POE encapsulant has poor adhesion to the top glass substrate of photovoltaic modules, and this defect is a bottleneck in the development of POE sealants. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a POE packaging material for photovoltaic modules and a preparation method thereof. The POE packaging material provided by the present invention has strong adhesion to a glass substrate, and has the advantages of high transmittance, high strength, high viscosity and long-term durability. Its light transmittance reaches more than 90%, and the peeling force is ≥36N / cm.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A POE packaging material for a photovoltaic module comprises the following raw materials: POE, silane-modified EPDM rubber, and a cross-linking agent.

[0009] The weight ratio of the POE, silane-modified EPDM rubber and cross-linking agent is 1:0.03-0.09:0.01-0.05.

[0010] The silane-modified EPDM rubber is 3-mercaptopropyltrimethoxysilane-modified EPDM rubber.

[0011] The cross-linking agent is dicumyl peroxide.

[0012] The preparation method of the 3-mercaptopropyltrimethoxysilane modified ethylene propylene diene rubber is as follows: ethylene propylene diene rubber and 3-mercaptopropyltrimethoxysilane are dispersed in toluene, stirred under the protection of an inert gas until completely dissolved to obtain a mixed solution, the mixed solution is irradiated with ultraviolet black light for 120 to 150 minutes; finally, poured into acetone for precipitation, filtered, washed, and dried.

[0013] Furthermore, the mass ratio of the EPDM rubber to 3-mercaptopropyltrimethoxysilane is 5 to 20:1.

[0014] The mass percentage concentration of the EPDM rubber in toluene is 0.1% to 0.2%.

[0015] The power of the ultraviolet black light irradiation is 15-25W.

[0016] The inert gas is nitrogen.

[0017] The present invention also provides a method for preparing the POE packaging material for photovoltaic modules, which comprises the following steps: placing POE, silane-modified EPDM rubber and a cross-linking agent into a stirring kettle in sequence according to a formula ratio for mixing, the stirring time is 6 to 8 hours, the mixing temperature is 55 to 65°C, until the additive is completely absorbed and the overall temperature of the mixed material drops to room temperature, and a film is prepared by a cast extrusion processing method.

[0018] The melt extrusion conditions are: the extruder head temperature is 95°C to 110°C, and the main engine speed is 7 to 16 r / min; specifically: the mixed material is compounded in an extruder with a main engine speed of 7 to 16 r / min for 10 minutes, then melt-extruded at 95°C to 110°C, and cast into a film and rolled up.

[0019] The POE packaging material for photovoltaic modules provided by the present invention comprises POE, silane-modified EPDM rubber and a cross-linking agent as raw materials. The addition of the silane-modified EPDM rubber increases the polarity of the adhesive film, promotes the adhesion between the POE packaging material and the glass substrate, and improves the adhesion strength between the POE packaging material and the glass substrate.

[0020] The present invention modifies EPDM through a thioene-click reaction between EPDM and MPTS, and after modification, mixes with POE, melt-extrudes, casts into a film, and then rolls up to prepare a POE packaging material, thereby directly avoiding the need for additional grafting silane during the lamination process.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) After pure POE is cross-linked with silane-modified EPDM rubber, its recrystallization temperature and melting temperature are reduced due to the interruption of polymer chain fluidity, which is beneficial to energy conservation and emission reduction and improving the processing performance of the material.

[0023] (2) The transmittance of the POE packaging material prepared by the present invention can reach more than 90%.

[0024] (3) The POE packaging material prepared by the present invention has significantly improved peel strength with glass compared with pure POE material, thereby improving the adhesion strength of the packaging material. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the embodiments.

[0026] The MFI of POE used in the present invention at 190° C. is 13 g / 10 min.

[0027] The ethylene content of EPDM is 57%.

[0028] Example 1

[0029] A POE packaging material for a photovoltaic module consists of POE, 3-mercaptopropyltrimethoxysilane-modified ethylene propylene diene rubber and dicumyl peroxide in a mass ratio of 1:0.03:0.02.

[0030] The preparation method of the POE packaging material for photovoltaic modules is as follows:

[0031] (1) Preparation of 3-mercaptopropyltrimethoxysilane-modified ethylene propylene diene monomer rubber: EPDM and MPTS were added to toluene to make the mass percentage concentration of the two to be 0.1% and 0.01%, respectively. Under the protection of 50 mL / min nitrogen, the mixture was stirred until the solute was observed to be completely dissolved. The mixture was then exposed to an ultraviolet black light with a power of 18 W for 150 min. Finally, the mixture was poured into 4 times its weight of acetone to precipitate the product. The product was filtered, washed with anhydrous ethanol for 3 times, and then kept in vacuum at 60°C for 1 day to be completely dried. The obtained product was recorded as m-EDPM.

[0032] (2) POE, m-EDPM and DCP were placed in a stirring kettle in accordance with the formula ratio for mixing. The mixing time was 6 to 8 hours at a temperature of 55 to 65°C until the additives were completely absorbed. The overall temperature of the mixed material was reduced to room temperature. The mixed material was compounded in an extruder with a main engine speed of 14 r / min for 10 minutes, then melt-extruded at 105°C, cast into a film and rolled up. The amount of m-EDPM added was 3% of the mass of POE, and the amount of DCP added was 2% of the mass of POE. The obtained product was recorded as POE / m-EDPM.

[0033] Example 2

[0034] A POE packaging material for a photovoltaic module consists of POE, 3-mercaptopropyltrimethoxysilane-modified ethylene propylene diene rubber and dicumyl peroxide in a mass ratio of 1:0.06:0.02.

[0035] The preparation method of the POE packaging material for photovoltaic modules is the same as that of Example 1, except that in step (2), the amount of m-EDPM added is 6% of the mass of POE, and the amount of DCP added is 2% of the mass of POE.

[0036] Example 3

[0037] A POE packaging material for a photovoltaic module consists of POE, 3-mercaptopropyltrimethoxysilane-modified ethylene propylene diene rubber and dicumyl peroxide in a mass ratio of 1:0.09:0.02.

[0038] The preparation method of the POE packaging material for photovoltaic modules is the same as that of Example 1, except that in step (2), the amount of m-EDPM added is 9% of the mass of POE, and the amount of DCP added is 2% of the mass of POE.

[0039] Comparative Example 1

[0040] The other steps are the same as those in Example 1, except that 3-mercaptopropyltrimethoxysilane-modified ethylene propylene diene rubber is not added as the raw material.

[0041] The POE packaging materials prepared in the above embodiments and comparative examples were subjected to performance tests, and the test items and test methods are as follows:

[0042] ①DSC measurement thermal analysis: To clarify the thermal behavior of m-EDPM / POE compounds, the spectra during cooling and reheating (i.e. before and after crosslinking) were recorded. Under nitrogen, the sample was rapidly heated to 120°C, held for 2 minutes to destroy anisotropy, and then cooled to -75°C at a rate of 20°C / min to analyze the recrystallization behavior. Finally, the crystallized sample was heated again to 120°C at a rate of 20°C / min to analyze the melting behavior.

[0043] ② Cross-linking degree test: xylene extraction technology.

[0044] ③Transmittance test: measure the transmission spectrum within the wavelength range of 250-800nm.

[0045] ④Tensile strength & elongation at break: The tensile test was conducted in accordance with ASTM D412 and measured at a constant speed of 500 mm / min. The test was evaluated based on the average value of at least five parallel tests.

[0046] ⑤ Peel force: According to ASTM 3330M method, at 25°C, with a separation angle of about 180° and a separation rate of 150 mm / min.

[0047] ⑥Wet heat test: The photovoltaic modules were encapsulated with m-EPDM / POE compounds and tested for 1000 hours at 85°C and 85% relative humidity in accordance with the requirements of IEC-61215. The fill factor (FF) and power conversion efficiency (PCE) values ​​before and after aging were calculated using the IV curve.

[0048] The test results are shown in Table 1.

[0049] Table 1

[0050]

[0051] From the test results in Table 1, it can be seen that regardless of the cross-linking state, the thermal and mechanical properties of the POE compound will not change significantly with the increase of the m-EPDM content, but the bonding strength between the POE encapsulation material and the glass substrate will increase linearly with the increase of the m-EPDM content, which shows that the m-EPDM obtained with silane EPDM acts as an adhesion promoter for the glass substrate. The main reason is that the present invention constructs silane-grafted EPDM (m-EPDM), improves the adhesion strength with the glass substrate through the thioene-click reaction between EPDM and MPTS, and then composites POE with m-EPDM, directly avoiding the need for additional grafting of silane during the lamination process. Even after 1000 hours under wet heat test conditions, the power loss of POE / m-EPDM is less than that of POE, which shows the long-term durability of the photovoltaic module encapsulated by the m-EPDM / POE film.

[0052] The above-mentioned detailed description of a POE packaging material for photovoltaic modules and its preparation method with reference to the embodiments is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A POE packaging material for photovoltaic modules, characterized in that: It includes the following raw materials: POE, silane-modified EPDM rubber, and cross-linking agent.

2. The POE packaging material for photovoltaic modules according to claim 1, characterized in that: The weight ratio of the POE, silane-modified EPDM rubber and cross-linking agent is 1:0.03-0.09:0.01-0.

05.

3. The POE packaging material for photovoltaic modules according to claim 1 or 2, characterized in that: The silane-modified EPDM rubber is 3-mercaptopropyltrimethoxysilane-modified EPDM rubber.

4. The POE packaging material for photovoltaic modules according to claim 1 or 2, characterized in that: The cross-linking agent is dicumyl peroxide.

5. The POE packaging material for photovoltaic modules according to claim 3, characterized in that: The preparation method of the 3-mercaptopropyltrimethoxysilane modified ethylene propylene diene rubber is as follows: ethylene propylene diene rubber and 3-mercaptopropyltrimethoxysilane are dispersed in toluene, stirred under the protection of an inert gas until completely dissolved to obtain a mixed solution, the mixed solution is irradiated with ultraviolet black light for 120 to 150 minutes; finally, poured into acetone for precipitation, filtered, washed, and dried.

6. The POE packaging material for photovoltaic modules according to claim 5, characterized in that: The mass ratio of the EPDM rubber to 3-mercaptopropyltrimethoxysilane is 5 to 20:

1.

7. The POE packaging material for photovoltaic modules according to claim 5, characterized in that: The mass percentage concentration of the EPDM rubber in toluene is 0.1% to 0.2%.

8. The POE packaging material for photovoltaic modules according to claim 5, characterized in that: The power of the ultraviolet black light irradiation is 15-25W.

9. The method for preparing a POE encapsulation material for a photovoltaic module according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: placing POE, silane-modified EPDM rubber and a cross-linking agent into a stirring kettle in order according to a formula ratio for mixing, the mixing time is 6 to 8 hours, the mixing temperature is 55 to 65° C., until the additive is completely absorbed, the overall temperature of the mixed material drops to room temperature, and the film is rolled up after melt extrusion and cast film formation.

10. The preparation method according to claim 9, characterized in that: The conditions for the melt extrusion are: the extruder head temperature is 95° C. to 110° C., and the main engine speed is 7 to 16 r / min.

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