A polyolefin packaging film for single and double glass TOPcon modules and its preparation method

Abstract

The present invention relates to a polyolefin encapsulation film for single-glass and double-glass TOPcon modules. The polyolefin encapsulation film comprises a POE layer, an adhesive layer, and an EVA layer stacked in sequence. The adhesive layer comprises a hyperbranched polyimide polymer represented by structural formula I, wherein the main chain is connected to polyimide segments via a triazine structure, while the side chains are connected to PEG segments and polysiloxane segments, respectively, on the triazine structure. The raw materials for at least one of the POE, adhesive, and EVA layers also include a functional additive. The polyolefin encapsulation film for single-glass and double-glass TOPcon modules of the present invention combines the advantages of POE and EVA materials while exhibiting resistance to moisture and heat aging and PID (Polyvinyl Deficiency) to meet the packaging performance requirements of single-glass and double-glass TOPcon modules under long-term harsh conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaics, and in particular to a polyolefin packaging film for single- and double-glass TOPcon modules and a preparation method thereof. Background Art

[0002] TOPcon solar cells, a new type of solar cell, have become a hot topic in the photovoltaic industry in recent years. Photovoltaic modules can be divided into single-glass and double-glass modules. Double-glass modules utilize a novel packaging method, offering a range of performance advantages over traditional single-glass modules and representing the future of photovoltaic module development. The double-glass module structure can accommodate a variety of cell technologies, and the new bifacial cell technology places special demands on the packaging material. Currently, photovoltaic module encapsulation generally utilizes EVA or POE films. POE offers superior overall performance in all aspects, but at a higher cost. EVA and POE are often co-extruded to reduce costs. However, forcibly co-extruding non-polar POE and polar EVA together can weaken the adhesion between the layers after aging, leading to delamination and reduced module reliability. Furthermore, aging can lead to degradation and release of acidic substances, which can corrode TOPcon module components and prevent them from passing PID testing. Summary of the Invention

[0003] In view of the above shortcomings of the existing technology, the present invention, on the one hand, provides a polyolefin packaging film for single-glass and double-glass TOPcon modules to solve the problem that the existing TOPcon module packaging film cannot have both moisture and heat aging resistance and PID resistance, so that it can simultaneously meet the packaging performance requirements of single-glass and double-glass TOPcon modules under long-term harsh conditions.

[0004] In order to achieve the above objects, the technical solution adopted by the present invention is:

[0005] A polyolefin packaging film for single-glass and double-glass TOPcon modules, comprising a POE layer, a bonding layer, and an EVA layer stacked in sequence; the bonding layer comprises a hyperbranched polyimide polymer represented by structural formula I.

[0006]

[0007] In the formula, R1 is a polyimide segment, R2 is a PEG segment, R3 is a polysiloxane segment, and a and b are independently natural numbers of 10 to 30; at least one of the film layer materials of the POE layer, the bonding layer, and the EVA layer also includes a functional additive. The polyolefin encapsulation film of the present invention uses the hyperbranched polyimide polymer shown in structural formula I as the bonding layer raw material to composite the POE layer and the EVA layer into one. Compared with the current encapsulation film prepared by co-extruding non-polar POE and polar EVA, the polyolefin encapsulation film of the present invention has superior aging resistance. After long-term use, the bonding force between the layers will not be significantly reduced, and delamination is not likely to occur, resulting in reduced reliability of the photovoltaic module. The raw material composition of the bonding layer of the present invention includes a hyperbranched polyimide polymer shown in structural formula I, whose main chain is connected to the polyimide segment at a triazine structure, and the side chains are connected to the triazine structure with PEG segments and polysiloxane segments respectively. The adhesive layer raw material of the present invention has excellent adhesion properties with the POE layer and the EVA layer through the synergistic effect of the polyimide segment, the PEG segment and the polysiloxane segment; and the introduction of the triazine structure further effectively improves the moisture and heat aging resistance of the polyolefin encapsulation film of the present invention.

[0008] Preferably, the synthesis route of the hyperbranched polyimide polymer is as follows: first, 2,4,6-trichloro-1,3,5-triazine and amino-terminated polyimide are polymerized under ice bath conditions to obtain a polymer backbone; then, polar group-terminated PEG-NH2 and trialkoxysilylaniline are added and the temperature is raised to carry out a heating reaction, and then the hyperbranched polyimide polymer is finally obtained after a hydrolysis reaction.

[0009] Preferably, the molar ratio of the 2,4,6-trichloro-1,3,5-triazine to the amino-terminated polyimide is 1:1; and the molar ratio of the polar group-terminated PEG-NH2 to trialkoxysilylaniline is 1:1.

[0010] Preferably, the amine-terminated polyimide is obtained by reacting 4,4-hexafluoroisopropylphthalic anhydride and 4,4'-diaminodiphenyl ether monomers.

[0011] Preferably, the polar group-terminated NH2-PEG is at least one of NH2-PEG-NH2 (double-terminated amino polyethylene glycol), NH2-PEG-OH (amino PEG hydroxyl), NH2-PEG-CH2CH2COOH (amino PEG propionic acid), and NH2-PEG-Mal (amino PEG maleimide). In the polar group-terminated NH2-PEG of the present invention, the amino group connected to one end of PEG (Chinese name, polyethylene glycol) can undergo a substitution reaction with the chlorine atom on the triazine structure, so that the hyperbranched polyimide polymer is grafted with polar group-terminated PEG. Furthermore, by introducing the polar group-terminated NH2-PEG, the adhesive layer and the polar EVA layer have good compatibility, further ensuring the long-term stable encapsulation effect of the photovoltaic module. The introduction of the polar group-terminated NH2-PEG of the present invention is conducive to suppressing or absorbing the release of acidic substances caused by aging and degradation of the EVA layer, thereby ensuring that the TOPcon module passes the PID test smoothly and ensures the long-term stable high-power output of the photovoltaic module.

[0012] Preferably, the trialkoxysilylaniline is at least one of 4-(triethoxysilyl)aniline, 3-[3-(trimethoxysilyl)propoxy]aniline, and 4-(trimethoxysilyl)aniline. The amino functional groups of the trialkoxysilylaniline of the present invention can undergo a substitution reaction with the chlorine atoms on the triazine structure, resulting in a hyperbranched polyimide polymer grafted with trialkoxysilyl groups. The trialkoxysilyl groups can be further hydrolyzed to produce polysiloxane segments.

[0013] Preferably, the POE layer comprises a polyolefin resin and a modified polyolefin resin. The polyolefin resin comprises at least one of ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-octene copolymer, ethylene-isobutylene copolymer, ethylene-1-hexene copolymer, ethylene-1-heptene copolymer, ethylene-1-nonene copolymer, or ethylene-1-decene copolymer.

[0014] Preferably, the modified polyolefin resin is obtained by a modification reaction of POE, a crosslinking agent, a co-crosslinking agent, and a silane coupling agent. The polyolefin resin of the present invention is modified with a silane coupling agent, resulting in excellent compatibility between the POE layer and the hyperbranched polyimide polymer in the adhesive layer, further ensuring long-term and stable encapsulation of the photovoltaic module.

[0015] Preferably, the functional auxiliary agent is at least one of an antioxidant, an ultraviolet absorber and an ultraviolet stabilizer.

[0016] Another aspect of the present application is to provide a method for preparing a polyolefin packaging film for single- and double-glass TOPcon modules as described above, the preparation method comprising the following steps: mixing at least one masterbatch of the POE layer, the bonding layer and the EVA layer with a functional additive, and then using a twin-screw extruder to melt-extrude the POE layer, the bonding layer and the EVA layer raw materials to prepare the POE layer masterbatch, the bonding layer masterbatch and the EVA layer masterbatch respectively; then, the POE layer masterbatch, the bonding layer masterbatch and the EVA layer masterbatch are sequentially cast to prepare the polyolefin packaging film for single- and double-glass TOPcon modules.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The polyolefin encapsulation film of the present invention combines the advantages of both POE and EVA materials as TOPcon photovoltaic module encapsulation films. By using a hyperbranched polyimide polymer represented by structural formula I as the bonding layer, the POE and EVA layers are integrated into a single body. This prevents delamination and improves the film's resistance to moisture-heat aging and PID (Polyvinyl Deficit) (PID) resistance, ensuring long-term, stable, and high-power output from the photovoltaic module.

[0019] The polyolefin packaging film of the present invention can be used for single-glass and double-glass TOPcon modules, has high reliability and long service life, and can meet the packaging performance requirements of single-glass and double-glass TOPcon modules under long-term harsh conditions. DETAILED DESCRIPTION

[0020] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may conceive of other obvious variations.

[0021] Example 1

[0022] The polyolefin packaging film for single-glass and double-glass TOPcon modules of this embodiment comprises a POE layer, a bonding layer and an EVA layer stacked in sequence; the bonding layer comprises a hyperbranched polyimide polymer as shown in structural formula I,

[0023]

[0024] In the formula, R1 is a polyimide segment, R2 is a PEG segment, R3 is a polysiloxane segment, and a and b are independently a natural number 15; the raw material composition of the EVA layer includes EVA resin and functional additives in a mass ratio of 100:1. The raw material composition of the POE layer includes polyolefin resin (ethylene-1-butene copolymer), modified polyolefin resin and functional additives in a mass ratio of 70:30:1. The functional additives are composed of an antioxidant (tris(2,4-di-tert-butylphenyl) phosphite), a UV absorber (2-hydroxy-4-n-octyloxybenzophenone) and a UV stabilizer (bis-2,2,6,6-tetramethylpiperidinol sebacate) in a mass ratio of 5:2:2; the amount of the functional additives added to the POE layer and the EVA layer is 0.5wt%. The modified polyolefin resin is obtained by heating POE (ethylene-1-butene copolymer), a crosslinking agent (tert-butyl perbenzoate), a co-crosslinking agent (triallyl cyanurate) and a silane coupling agent (vinyltrimethoxysilane) in a mass ratio of 100:1:0.5:0.5 to 120°C for a modification reaction.

[0025] The synthesis route of the hyperbranched polyimide polymer is as follows: 2,4,6-trichloro-1,3,5-triazine (8 mmol), amine-terminated polyimide (8 mmol) and N,N-diisopropylethylamine (15 mmol) are first added to 100 mL of THF solvent, and the reaction is carried out at 10° C. for 12 hours to obtain a polymer main chain; then, NH2-PEG-OH (amino PEG hydroxyl) (4 mmol) and 4-(triethoxysilyl)aniline (4 mmol) are added to a vacuum reactor, the temperature is raised to 80° C., a heating reaction is carried out for 8 hours, and then the hyperbranched polyimide polymer is finally obtained after a hydrolysis reaction.

[0026] Preparation of the amine-terminated polyimide: 4,4-hexafluoroisopropylphthalic anhydride (4 mmol) and 4,4'-diaminodiphenyl ether (6 mmol) monomers are placed in a reaction kettle filled with toluene solvent, heated to 170° C. and reacted for 8 hours to obtain the target product, namely, the amine-terminated polyimide.

[0027] The method for preparing a polyolefin packaging film for single- and double-glass TOPcon modules in this embodiment comprises the following steps: first, mixing POE layer raw materials including a polyolefin resin, a modified polyolefin resin, and a functional additive, and then using a twin-screw extruder to melt-extrude the POE layer raw materials at 90° C. to prepare a POE layer masterbatch; secondly, mixing EVA layer raw materials including an EVA resin and a functional additive, and also using a twin-screw extruder to melt-extrude the EVA layer raw materials at 90° C. to prepare an EVA layer masterbatch; finally, sequentially casting the POE layer masterbatch, the bonding layer masterbatch, and the EVA layer masterbatch to prepare the polyolefin packaging film for single- and double-glass TOPcon modules; the thicknesses of the POE layer, the bonding layer, and the EVA layer are 0.5 mm, 0.2 mm, and 0.5 mm, respectively.

[0028] Example 2

[0029] The polyolefin packaging film for single-glass and double-glass TOPcon modules of this embodiment comprises a POE layer, a bonding layer and an EVA layer stacked in sequence; the bonding layer comprises a hyperbranched polyimide polymer as shown in structural formula I,

[0030]

[0031] In the formula, R1 is a polyimide segment, R2 is a PEG segment, and R3 is a polysiloxane segment. a and b are independently a natural number 15. The EVA layer comprises an EVA resin and a functional additive in a mass ratio of 100:1. The POE layer comprises a polyolefin resin (ethylene-isobutylene copolymer), a modified polyolefin resin, and a functional additive in a mass ratio of 70:30:1. The functional additive is the same as in Example 1. The modified polyolefin resin differs from that in Example 1 in that the POE is an ethylene-isobutylene copolymer.

[0032] The synthesis route of the hyperbranched polyimide polymer is as follows: first, 2,4,6-trichloro-1,3,5-triazine (8 mmol), amino-terminated polyimide (8 mmol) and N,N-diisopropylethylamine (15 mmol) are added to 100 mL of THF solvent, and the reaction is carried out at 10° C. for 12 hours to obtain a polymer main chain; then, NH2-PEG-NH2 (double-terminated amino polyethylene glycol) (4 mmol) and 3-[3-(trimethoxysilyl)propoxy]aniline (4 mmol) are added to a vacuum reactor, the temperature is raised to 80° C., and the reaction is heated for 8 hours, and then the hyperbranched polyimide polymer is finally obtained after a hydrolysis reaction.

[0033] The preparation of the amine-terminated polyimide is the same as that in Example 1. The preparation method of the polyolefin encapsulation film for the single-glass and double-glass TOPcon modules in this embodiment is the same as that in Example 1.

[0034] Example 3

[0035] The polyolefin packaging film for single-glass and double-glass TOPcon modules of this embodiment comprises a POE layer, a bonding layer and an EVA layer stacked in sequence; the bonding layer comprises a hyperbranched polyimide polymer as shown in structural formula I,

[0036]

[0037] In the formula, R1 is a polyimide segment, R2 is a PEG segment, and R3 is a polysiloxane segment. a and b are independently a natural number 15. The EVA layer comprises an EVA resin and a functional additive in a mass ratio of 100:1. The POE layer comprises a polyolefin resin (ethylene-1-hexene copolymer), a modified polyolefin resin, and a functional additive in a mass ratio of 70:30:1. The functional additive is the same as in Example 1. The modified polyolefin resin differs from that in Example 1 in that the POE is an ethylene-1-hexene copolymer.

[0038] The synthesis route of the hyperbranched polyimide polymer is as follows: 2,4,6-trichloro-1,3,5-triazine (8 mmol), terminal amino polyimide (8 mmol) and N,N-diisopropylethylamine (15 mmol) are first added to 100 mL of THF solvent, and the reaction is carried out at 10° C. for 12 hours to obtain a polymer main chain; then, NH2-PEG-Mal (amino PEG maleimide) (4 mmol) and 4-(trimethoxysilyl)-aniline (4 mmol) are added to a vacuum reactor, the temperature is raised to 80° C., a heating reaction is carried out for 8 hours, and then the hyperbranched polyimide polymer is finally obtained after a hydrolysis reaction.

[0039] The preparation of the amine-terminated polyimide is the same as that in Example 1. The preparation method of the polyolefin encapsulation film for the single-glass and double-glass TOPcon modules in this embodiment is the same as that in Example 1.

[0040] The polyolefin encapsulation films prepared in Examples 1 to 3 were subjected to performance tests, and the performance results are shown in Table 1:

[0041] Among them, the transmittance, peel strength and moisture-heat aging resistance are tested in accordance with GB / T29848; the test conditions for anti-PID performance are 85℃, 85RH%, and the test is carried out by applying a voltage of -1000V. After 1000h, its PID power attenuation rate is tested.

[0042] Table 1

[0043]

[0044] It can be seen that the present invention has considerable advantages over the currently used technologies. The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the invention claimed.

Claims

1. A polyolefin packaging film for single and double glass TOPcon modules, characterized in that: The polyolefin encapsulation film comprises a POE layer, a bonding layer and an EVA layer stacked in sequence; the bonding layer raw material composition comprises a hyperbranched polyimide polymer shown in structural formula I, In the formula, R1 is a polyimide segment, R2 is a PEG segment, R3 is a polysiloxane segment, and a and b are independently natural numbers of 10 to 30; At least one of the film layer materials among the POE layer, the adhesive layer and the EVA layer further includes a functional additive; The synthesis route of the hyperbranched polyimide polymer is as follows: 2,4,6-trichloro-1,3,5-triazine and amino-terminated polyimide are first polymerized under ice bath conditions to obtain a polymer backbone; then polar group-terminated PEG-NH2 and trialkoxysilylaniline are added and heated to react; and finally, the hyperbranched polyimide polymer is obtained after a hydrolysis reaction.

2. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The molar ratio of the 2,4,6-trichloro-1,3,5-triazine to the amino-terminated polyimide is 1:1; the molar ratio of the polar group-terminated PEG-NH2 to trialkoxysilylaniline is 1:

1.

3. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The amino-terminated polyimide is obtained by reacting 4,4-hexafluoroisopropylphthalic anhydride and 4,4'-diaminodiphenyl ether monomers.

4. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The polar group-terminated NH2-PEG is at least one of NH2-PEG-NH2 (double-terminated amino polyethylene glycol), NH2-PEG-OH (amino PEG hydroxyl), NH2-PEG-CH2CH2COOH (amino PEG propionic acid), and NH2-PEG-Mal (amino PEG maleimide).

5. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The trialkoxysilylaniline is at least one of 4-(triethoxysilyl)aniline, 3-[3-(trimethoxysilyl)propoxy]aniline, and 4-(trimethoxysilyl)-aniline.

6. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The raw materials of the POE layer include polyolefin resin and modified polyolefin resin.

7. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 6, characterized in that: The modified polyolefin resin is obtained by modification reaction of POE, a crosslinking agent, an auxiliary crosslinking agent and a silane coupling agent.

8. The polyolefin packaging film for single-glass and double-glass TOPcon modules according to claim 1, characterized in that: The functional auxiliary agent is at least one of an antioxidant, an ultraviolet absorber and an ultraviolet stabilizer.

9. A method for preparing a polyolefin packaging film for single-glass and double-glass TOPcon modules according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: mixing at least one masterbatch of the POE layer, the bonding layer and the EVA layer with a functional additive, and then using a twin-screw extruder to melt-extrude the raw materials of the POE layer, the bonding layer and the EVA layer respectively to prepare the POE layer masterbatch, the bonding layer masterbatch and the EVA layer masterbatch; and then casting the POE layer masterbatch, the bonding layer masterbatch and the EVA layer masterbatch in sequence to prepare the polyolefin encapsulation film for the single- and double-glass TOPcon modules.

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