Modified polyolefin elastomer packaging adhesive film as well as preparation method and application thereof

Abstract

The invention provides a modified polyolefin elastomer packaging adhesive film as well as a preparation method and application thereof, and the modified polyolefin elastomer packaging adhesive film is prepared from the following raw materials in parts by weight: 80-96 parts of polyolefin elastomer, 0.8-3 parts of main crosslinking agent, 0.5-3 parts of assistant crosslinking agent, 0.1-2 parts of silane, 0.2-1 part of acid acceptor and 0.1-1.5 parts of light stabilizer. The assistant crosslinking agent comprises a polybutadiene compound. According to the invention, the packaging adhesive film has the advantages of excellent adhesive property, excellent aging resistance, high volume resistivity, low water permeability, high friction coefficient, good barrier property and good anti-skid effect, and the light transmittance of the adhesive film is not affected.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic materials technology, specifically relating to a modified polyolefin elastomer encapsulating film, its preparation method, and its application. Background Technology

[0002] Photovoltaic cells can be classified into P-type and N-type cells based on their substrate material. P-type cells use P-type silicon wafers as substrates, while N-type cells use N-type silicon wafers. Since P-type cells are close to their theoretical efficiency limit, N-type cell technology is the future direction. Among them, TOPCon cells are currently the fastest-growing mainstream N-type cells on the market and are expected to become the mainstream choice in the module market within the next few years.

[0003] Although TOPCon solar cells boast a theoretical efficiency of up to 28.7% and a production-ready peak efficiency of 24-25%, along with advantages such as low degradation, high bifaciality, and low temperature coefficient, the front side of TOPCon cells uses silver-aluminum paste, which is more susceptible to corrosion from acids and moisture compared to conventional cells, leading to a decrease in module power generation. Therefore, this places higher demands on the performance of the encapsulation film used to protect the cells; the encapsulation film must possess characteristics such as low acid content, water resistance, and strong adhesion.

[0004] Currently, polyolefin elastomer (POE) encapsulant films are commonly used for single-glass TOPCon modules. However, traditional POE films struggle to meet performance requirements such as low acidity and high barrier properties. Therefore, co-crosslinking agents are typically added to the film formulation to reduce free acid and increase crosslinking density, achieving these performance requirements. However, conventional co-crosslinking systems often employ triallyl isocyanate (TAIC) and acrylate additives. Both of these materials have poor compatibility with POE, easily leading to additive precipitation and severe film slippage. This limits their use in modules and significantly impacts module production efficiency. Furthermore, after precipitation, additives can form a layer between the POE film and the glass, failing to fully exert their adhesive effect and affecting the bond strength between the film and glass, thus reducing the long-term reliability of the module. Additionally, conventional co-crosslinking systems result in films with poor aging resistance and low volume resistivity, further impacting the long-term reliability of the module.

[0005] Therefore, developing a POE encapsulation film with low acidity, high barrier properties, anti-slip effect, high bonding strength, good aging resistance, high volume resistivity, and unaffected light transmittance is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a modified polyolefin elastomer encapsulating film, its preparation method, and its applications. The modified polyolefin elastomer encapsulating film exhibits excellent adhesion, aging resistance, and high volume resistivity. Simultaneously, the encapsulating film has low water permeability, a high coefficient of friction, good barrier properties, and anti-slip effects, while maintaining unaffected light transmittance. This results in photovoltaic modules incorporating the encapsulating film achieving higher efficiency and a longer service life.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a modified polyolefin elastomer encapsulating film, wherein, by weight, the raw materials for preparing the modified polyolefin elastomer encapsulating film include 80-96 parts of polyolefin elastomer, 0.8-3 parts of primary crosslinking agent, 0.5-3 parts of co-crosslinking agent, 0.1-2 parts of silane, 0.2-1 parts of acid scavenger, and 0.1-1.5 parts of light stabilizer; the co-crosslinking agent includes polybutadiene compounds.

[0009] In this invention, the raw material of the modified polyolefin elastomer encapsulating film uses polybutadiene compounds as a crosslinking agent, which can improve the crosslinking density of the encapsulating film, resulting in an encapsulating film with higher bonding strength, better barrier properties, better aging resistance, and higher volume resistivity. At the same time, it can reduce the precipitation of additives, increase the friction coefficient of the encapsulating film, so that the encapsulating film has an anti-slip effect, and does not affect the light transmittance of the encapsulating film.

[0010] In this invention, the 80-96 parts of polyolefin elastomer can be, for example, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, 92 parts, 94 parts, 96 parts, etc.

[0011] In this invention, 0.8 to 3 parts of the main crosslinking agent can be, for example, 0.8 parts, 0.9 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, etc.

[0012] In this invention, 0.5 to 3 parts of the crosslinking agent can be, for example, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts, 0.8 parts, 0.85 parts, 0.9 parts, 0.95 parts, 1 part, 1.1 parts, 1.15 parts, 1.2 parts, 1.25 parts, 1.3 parts, 1.35 parts, 1.4 parts, 1.45 parts, 1.5 parts, 1.55 parts, 1.6 parts, 1.65 parts, 1.7 parts, 1.75 parts, 1.8 parts, 1.85 parts, 1.9 parts, 1.95 parts, 2 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3 parts, etc.

[0013] In this invention, 0.1 to 2 parts of silane can be, for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, etc.

[0014] In this invention, 0.2 to 1 part of acid absorbent can be, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, etc.

[0015] In this invention, 0.1 to 1.5 parts of light stabilizer can be, for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, etc.

[0016] Preferably, the polybutadiene compounds include homopolymers of butadiene and / or copolymers of butadiene.

[0017] Preferably, the homopolymer of butadiene includes liquid polybutadiene rubber and / or epoxidized polybutadiene.

[0018] Preferably, the number average molecular weight of the liquid polybutadiene rubber is 1000-8500, for example, it can be 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2500, 2800, 3000, 3200, 3400, 3500, 3600, 3800, 4000, 4200, 4500, 4800, 5000, 5200, 5500, 5800, 6000, 6200, 6500, 6800, 7000, 7200, 7500, 7800, 8000, 8200, 8400, etc.; more preferably, it is 2000-5000.

[0019] Preferably, the glass transition temperature of the liquid polybutadiene rubber is -90 to -45°C, for example, it can be -90°C, -88°C, -86°C, -84°C, -82°C, -80°C, -78°C, -75°C, -72°C, -70°C, -68°C, -65°C, -62°C, -60°C, -58°C, -55°C, -52°C, -50°C, -48°C, -46°C, etc.; more preferably, it is -85 to -65°C.

[0020] Preferably, at 25°C, the viscosity of the liquid polybutadiene rubber is 700–15000 cps, for example, 700 cps, 800 cps, 900 cps, 1000 cps, 1500 cps, 2000 cps, 2500 cps, 3000 cps, 3500 cps, 4000 cps, 4500 cps, 5000 cps, 5500 cps, 6000 cps, 6500 cps, 7000 cps, 7500 cps, 8000 cps, 8500 cps, 9000 cps, 9500 cps, 10000 cps, 11000 cps, 12000 cps, 13000 cps, 14000 cps, 15000 cps, etc.; more preferably, it is 2000–10000 cps.

[0021] Preferably, the molar percentage of 1,2-vinyl in the liquid polybutadiene rubber is 25-70%, for example, it can be 25%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, etc.; more preferably, it is 28-58%.

[0022] In this invention, the liquid polybutadiene rubber includes, but is not limited to, at least one of Ricon130, Ricon131, Ricon134, Ricon142, Ricon156, and Ricon157 from Cray Valley; the epoxidized polybutadiene includes, but is not limited to, Ricon 657 from Cray Valley.

[0023] Preferably, the copolymer of butadiene includes liquid styrene-butadiene rubber and / or butadiene-styrene-divinylbenzene copolymer.

[0024] Preferably, the number average molecular weight of the liquid styrene-butadiene rubber is 3000 to 9000, for example, it can be 3000, 3200, 3400, 3500, 3600, 3800, 4000, 4200, 4500, 4800, 5000, 5200, 5500, 5800, 6000, 6200, 6500, 6800, 7000, 7200, 7500, 7800, 8000, 8200, 8400, 8600, 8800, 9000, etc.

[0025] Preferably, the glass transition temperature of the liquid styrene-butadiene rubber is -65 to -20°C, for example, it can be -65°C, -64°C, -62°C, -60°C, -58°C, -55°C, -52°C, -50°C, -48°C, -45°C, -42°C, -40°C, -38°C, -35°C, -32°C, -30°C, -28°C, -25°C, -22°C, -20°C, etc.

[0026] Preferably, at 25°C, the viscosity of the liquid styrene-butadiene rubber is 17,000 to 80,000 cps, for example, it can be 17,000 cps, 20,000 cps, 25,000 cps, 30,000 cps, 35,000 cps, 40,000 cps, 45,000 cps, 50,000 cps, 55,000 cps, 60,000 cps, 65,000 cps, 70,000 cps, 75,000 cps, 80,000 cps, etc.

[0027] Preferably, the molar percentage of 1,2-vinyl in the liquid styrene-butadiene rubber is 25-70%, for example, it can be 25%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, etc.

[0028] In this invention, the homopolymer of butadiene includes, but is not limited to, at least one of Ricon100, Ricon181, Ricon184, and Ricon257 from Cray Valley.

[0029] Preferably, the polybutadiene compound comprises a combination of polybutadiene compound A and polybutadiene compound B; the viscosity of polybutadiene compound A is lower than the viscosity of polybutadiene compound B.

[0030] Preferably, the mass ratio of polybutadiene compound A to polybutadiene compound B is 1:(1.1 to 1.8), wherein the specific values ​​in (1.1 to 1.8) can be, for example, 1.1, 1.12, 1.15, 1.18, 1.2, 1.22, 1.25, 1.28, 1.3, 1.32, 1.35, 1.38, 1.4, 1.42, 1.45, 1.48, 1.5, 1.52, 1.55, 1.58, 1.6, 1.62, 1.65, 1.68, 1.7, 1.72, 1.75, 1.78, 1.8, etc.

[0031] Preferably, the main crosslinking agent includes a peroxide-based crosslinking agent.

[0032] Preferably, the peroxide crosslinking agent includes at least one of 2-ethylhexyl carbonate tert-butyl peroxide, 2-ethylhexyl carbonate tert-amyl peroxide, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, or dicumyl peroxide.

[0033] Preferably, the silane includes at least one of propyltrioxyethyl isocyanate, vinyltriacetoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane.

[0034] Preferably, the acid absorbent comprises Mg4Al2(OH). 12 CO3·3H2O, Mg 15 Zn 0.5 Al2(OH) 12 CO·3H2O, Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·3H2O, Mg 15 Zn 0.5 Al2(OH) 12 CO3, Mg6Al2(OH) 16 CO3, Mg 4.5 Al2(OH) 13 At least one of CO3.

[0035] Preferably, the light stabilizer comprises at least one of the following: a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol (light stabilizer 622), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, or 2,2,6,6-tetramethyl-4-piperidinyl ester.

[0036] Preferably, the 2,2,6,6-tetramethyl-4-piperidinyl ester comprises bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0037] In a second aspect, the present invention provides a method for preparing a modified polyolefin elastomer encapsulating film according to the first aspect, the method comprising the following steps:

[0038] A polyolefin elastomer, a primary crosslinking agent, a secondary crosslinking agent, a silane, an acid absorber, and a light stabilizer are mixed and extruded to obtain the modified polyolefin elastomer encapsulation film.

[0039] Preferably, the extrusion casting temperature is 80-120°C, for example, 80°C, 90°C, 100°C, 110°C, 120°C, etc.

[0040] Thirdly, the present invention provides a photovoltaic module comprising a modified polyolefin elastomer encapsulating film according to the first aspect.

[0041] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] The modified polyolefin elastomer encapsulating film provided by this invention uses polybutadiene compounds as co-crosslinking agents, reducing or completely eliminating the addition of traditional TAIC and acrylate co-crosslinking agents. This results in an encapsulating film with a higher crosslinking density, which is beneficial for improving the adhesive strength, barrier properties, aging resistance, and volume resistivity of the encapsulating film. At the same time, it reduces the precipitation of additives, increases the friction coefficient of the encapsulating film, giving it an anti-slip effect, and does not affect the light transmittance of the encapsulating film. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0045] All materials used in this invention can be obtained commercially available or prepared using conventional methods. Unless otherwise specified, the materials used in this invention are as follows:

[0046] Polyolefin elastomers (POE)

[0047] POE-1: Dow PV8660.

[0048] POE-2: Dow PV8669.

[0049] Polybutadiene compounds

[0050] The polybutadiene compounds selected from the Ricon series of Cray Valley are shown in Table 1, with specific grades and related parameters listed below.

[0051] Table 1

[0052]

[0053]

[0054] Examples 1-10, Comparative Examples 1-2

[0055] Examples 1-10 and Comparative Examples 1-2 each provide a modified polyolefin elastomer encapsulating film. The raw materials for preparing the modified polyolefin elastomer encapsulating film are shown in Tables 2-4 by weight; where " / " indicates that the component is not in the formulation; the preparation method of the modified polyolefin elastomer encapsulating film includes: mixing polyolefin elastomer, main crosslinking agent, co-crosslinking agent, silane, acid scavenger and light stabilizer, and extruding and casting at 90°C to obtain the modified polyolefin elastomer encapsulating film.

[0056] Table 2

[0057]

[0058]

[0059] Table 3

[0060]

[0061] Table 4

[0062]

[0063]

[0064] Performance testing

[0065] The modified polyolefin elastomer encapsulating films provided in Examples 1-10 and Comparative Examples 1 and 2 were subjected to the following performance tests:

[0066] (1) Permeability: Tested according to ISO 15106-1:2003(E);

[0067] (2) Initial bond strength: The peel strength between the encapsulating film and the glass at 180° was tested according to GB / T 2790-1995 standard;

[0068] (3) Aging resistance: The encapsulating film is bonded to the glass and aged for 2000h (DH2000h) at a temperature of 85±2℃ and a humidity of 85±5%. The 180° peel strength between the encapsulating film and the glass after aging is tested according to GB / T 2790-1995 standard.

[0069] (4) Light transmittance: Tested in accordance with GB / T 2410-2008 Determination of transmittance and haze of transparent plastics;

[0070] (5) Volume resistivity: Tested in accordance with GB / T 1401-2006: Test methods for volume resistivity and surface resistivity of solid insulating materials;

[0071] (6) Coefficient of friction: Tested in accordance with GB / T 10006: Determination of coefficient of friction of plastic film and sheet.

[0072] The specific test results are shown in Table 5.

[0073] Table 5

[0074]

[0075] As shown in Table 5, compared with conventional crosslinking agents such as TAIC and acrylates, the modified polyolefin elastomer encapsulating film provided by this invention, by adding a polybutadiene-based crosslinking agent, can improve the barrier properties, adhesion properties, aging resistance, and volume resistivity of the encapsulating film. Simultaneously, it provides an anti-slip effect without affecting the light transmittance. The water permeability of the encapsulating film is ≤3.61%, the initial bond strength is ≥189.23 N / cm, and after DH2000h, the bond strength is ≥101.56 N / cm, the bond strength retention rate is ≥35%, and it exhibits good aging resistance. The volume resistivity is ≥1.23 × 10⁻⁶. 17 With a coefficient of friction ≥2.118, it has a good anti-slip effect.

[0076] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modified polyolefin elastomer encapsulating film, characterized in that, By weight, the raw materials for preparing the modified polyolefin elastomer encapsulating film include 80-96 parts of polyolefin elastomer, 0.8-3 parts of main crosslinking agent, 0.5-3 parts of co-crosslinking agent, 0.1-2 parts of silane, 0.2-1 parts of acid scavenger and 0.1-1.5 parts of light stabilizer; The crosslinking agent includes polybutadiene compounds.

2. The modified polyolefin elastomer encapsulating film according to claim 1, characterized in that, The polybutadiene compounds include homopolymers of butadiene and / or copolymers of butadiene.

3. The modified polyolefin elastomer encapsulating film according to claim 2, characterized in that, The homopolymer of butadiene includes liquid polybutadiene rubber and / or epoxidized polybutadiene; Preferably, the number average molecular weight of the liquid polybutadiene rubber is 1000-8500, more preferably 2000-5000; Preferably, the glass transition temperature of the liquid polybutadiene rubber is -90 to -45°C, more preferably -85 to -65°C; Preferably, at 25°C, the viscosity of the liquid polybutadiene rubber is 700–15000 cps, more preferably 2000–10000 cps; Preferably, the 1,2-vinyl content in the liquid polybutadiene rubber is 25-70%, more preferably 28-58%.

4. The modified polyolefin elastomer encapsulating film according to claim 2, characterized in that, The copolymer of butadiene includes liquid styrene-butadiene rubber and / or butadiene-styrene-divinylbenzene copolymer; Preferably, the number-average molecular weight of the liquid styrene-butadiene rubber is 3000-9000; Preferably, the glass transition temperature of the liquid styrene-butadiene rubber is -65 to -20°C; Preferably, at 25°C, the viscosity of the liquid styrene-butadiene rubber is 17,000 to 80,000 cps; Preferably, the 1,2-vinyl content in the liquid styrene-butadiene rubber is 25-70% in molar percentage.

5. The modified polyolefin elastomer encapsulating film according to any one of claims 1 to 4, characterized in that, The polybutadiene compounds include a combination of polybutadiene compound A and polybutadiene compound B; the viscosity of polybutadiene compound A is less than the viscosity of polybutadiene compound B; Preferably, the mass ratio of polybutadiene compound A to polybutadiene compound B is 1:(1.1 to 1.8).

6. The modified polyolefin elastomer according to any one of claims 1 to 5, characterized in that, The main crosslinking agent includes peroxide-based crosslinking agents; Preferably, the peroxide crosslinking agent includes at least one of 2-ethylhexyl carbonate tert-butyl peroxide, 2-ethylhexyl carbonate tert-amyl peroxide, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, or dicumyl peroxide. Preferably, the silane includes at least one of propyltrioxyethyl isocyanate, vinyltriacetoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane.

7. The modified polyolefin elastomer according to any one of claims 1 to 6, characterized in that, The acid absorbent includes Mg4Al2(OH). 12 CO3·3H2O, Mg 15 Zn 0.5 Al2(OH) 12 CO·3H2O, Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·3H2O, Mg 15 Zn 0.5 Al2(OH) 12 CO3, Mg6Al2(OH) 16 CO3, Mg 4.5 Al2(OH) 13 At least one of CO3; Preferably, the light stabilizer comprises at least one selected from the following: a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, or 2,2,6,6-tetramethyl-4-piperidinyl ester. Preferably, the 2,2,6,6-tetramethyl-4-piperidinyl ester comprises bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

8. A method for preparing a modified polyolefin elastomer encapsulating film according to any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: A polyolefin elastomer, a primary crosslinking agent, a secondary crosslinking agent, a silane, an acid absorber, and a light stabilizer are mixed and extruded to obtain the modified polyolefin elastomer encapsulation film.

9. The preparation method according to claim 8, characterized in that, The extrusion casting temperature is 80–120°C.

10. A photovoltaic module, characterized in that, The photovoltaic module includes the modified polyolefin elastomer encapsulating film according to any one of claims 1 to 7.

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