Nano-cellulose reinforced photovoltaic packaging adhesive film and preparation method and application thereof

Abstract

The invention provides a nanocellulose reinforced photovoltaic packaging adhesive film as well as a preparation method and application thereof. The preparation raw materials of the photovoltaic packaging adhesive film comprise the following components in parts by mass: 100 parts of a resin matrix, 0.01-0.5 part of nanocellulose, 0.05-2 parts of a cross-linking agent and 0.05-5 parts of an assistant cross-linking agent. The addition of the nanocellulose effectively improves the tensile strength of the adhesive film, and the high specific surface area and special surface chemical properties of the nanocellulose are utilized to increase the crosslinking density of a resin matrix and improve the mechanical strength and chemical stability of the adhesive film; the nanocellulose can be used as a carrier to load other functional aids, so that the problem of mobility of the aids is solved. The nano-crystalline cellulose used in the invention has the characteristics of renewable raw materials, good dispersibility and excellent mechanical properties, the mechanical properties of the obtained photovoltaic adhesive film are obviously improved, and the method plays a positive role in light and thin development of photovoltaic modules.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules and relates to a nanocellulose reinforced photovoltaic encapsulation film and a preparation method and application thereof. Background Art

[0002] Photovoltaic encapsulation film, a crucial component of solar cell modules, bonds the solar panels to the glass and backsheet within the module structure, protecting the cells from environmental damage. The trend toward thinner and lighter photovoltaic modules requires improved performance from photovoltaic films to balance the impact of thinning tempered glass, such as enhanced mechanical properties and UV resistance.

[0003] Scholars in the photovoltaic film industry have conducted some research on this. CN114736617A discloses a high-strength and high-stability photovoltaic film, its preparation method, and application. This invention enhances the tensile strength of the film by adding an ultra-high molecular weight polyethylene fiber reinforcement layer to the film layer, thereby extending the service life of the photovoltaic film and photovoltaic modules. This method achieves this effect by sandwiching a fiber reinforcement layer between the film layers. In fact, the strength of the film layer itself is not improved, and the low light transmittance of the reinforcement layer affects the overall light transmittance. CN112063337A discloses a photovoltaic film resistant to mechanical impact and its preparation method. This invention uses an elastomer resin system, a hot-melt thermosetting resin system, and glass fiber to prepare a photovoltaic film with improved mechanical properties. Glass fiber plays a role in improving the mechanical strength of the system, but the addition of glass fiber affects the overall dispersibility and molding processability. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a nanocellulose reinforced photovoltaic encapsulation film and its preparation method and application. The present invention uses renewable material nanocellulose as a special additive to improve the tensile strength and anti-ultraviolet aging performance of the photovoltaic encapsulation film. First, the high tensile strength of nanocellulose is fully utilized; second, the high specific surface area and special surface chemical properties of nanocellulose are utilized to increase the cross-linking density of the resin, improve the mechanical strength and chemical stability; third, the porous network structure and special surface chemical properties of nanocellulose can achieve a high loading amount and strong binding force of the additive, and prevent the additive from migrating to the surface of the film.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a nanocellulose-enhanced photovoltaic encapsulation film, wherein the raw materials for preparing the photovoltaic encapsulation film include the following components in parts by weight:

[0007] 100 parts by mass of a resin matrix, 0.01 to 0.5 parts by mass of nanocellulose, 0.05 to 2 parts by mass of a cross-linking agent, and 0.05 to 5 parts by mass of an auxiliary cross-linking agent.

[0008] In this invention, the addition of nanocellulose effectively improves the tensile strength of the film. The high specific surface area and unique surface chemical properties of nanocellulose increase the crosslink density of the resin matrix, improving the film's mechanical strength and chemical stability. Nanocellulose can also serve as a carrier for other functional additives, addressing additive mobility issues. The nanocellulose used in this invention is a renewable raw material with good dispersibility and excellent mechanical properties. The resulting photovoltaic film exhibits significantly improved mechanical properties, contributing positively to the development of thinner and lighter photovoltaic modules.

[0009] The content of the nanocellulose in the raw materials for preparing the photovoltaic encapsulation film of the present invention can be 0.01 mass parts, 0.05 mass parts, 0.1 mass parts, 0.2 mass parts, 0.3 mass parts, 0.4 mass parts or 0.5 mass parts, the content of the cross-linking agent can be 0.05 mass parts, 0.1 mass parts, 0.5 mass parts, 1 mass parts, 1.2 mass parts, 1.4 mass parts, 1.6 mass parts, 1.8 mass parts or 2 mass parts, and the content of the auxiliary cross-linking agent can be 0.05 mass parts, 0.08 mass parts, 0.1 mass parts, 0.3 mass parts, 0.5 mass parts, 1 mass part, 2 mass parts, 3 mass parts, 4 mass parts or 5 mass parts.

[0010] Preferably, the resin matrix is one or a combination of at least two of ethylene-vinyl acetate copolymer, ethylene copolymer, propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer, preferably ethylene-vinyl acetate copolymer or ethylene-octene copolymer.

[0011] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 10-33%, for example, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30% or 33%, preferably 28-33%; the melt index is 10-43 g / 10min, for example, 10 g / 10min, 13 g / 10min, 15 g / 10min, 18 g / 10min, 20 g / 10min, 25 g / 10min, 30 g / 10min, 35 g / 10min, 40 g / 10min or 43 g / 10min, preferably 15-25 g / 10min.

[0012] Preferably, the melt index of the ethylene-octene copolymer is 3 to 30 g / 10 min, for example, 3 g / 10 min, 5 g / 10 min, 8 g / 10 min, 10 g / 10 min, 13 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, preferably 5 to 15 g / 10 min.

[0013] In the present invention, the nanocellulose is a nanofiber material made by processing plant fibers, including cellulose nanofibers (CNF) and cellulose nanocrystals (CNC), preferably cellulose nanofibers (CNF).

[0014] Preferably, the solid content of the cellulose nanofibers is greater than 95%, for example, it can be 96%, 97%, 98%, 99%, 99.3%, 99.5%, 99.8%, etc., preferably a solid content greater than 99%; the fiber diameter is 3 to 100 nm, for example, 3 nm, 5 nm, 8 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, preferably 10 to 50 nm; the fiber length is 0.2 to 10 μm, preferably 0.5 to 3 μm.

[0015] In the present invention, the functional nanocellulose is nanocellulose loaded with a functional additive.

[0016] Preferably, the mass ratio of the functional additive to the nanocellulose is 0.2:1 to 10:1, for example, 0.2:1, 0.3:1, 0.5:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0017] The functional nanocellulose of the present invention can be added to photovoltaic films as an additive, replacing the direct addition of additives and solving the problem of additive migration. During the production and use of commercial photovoltaic films, internal additives can migrate to the surface, affecting their performance. By leveraging the high loading capacity and multifunctional properties of nanocellulose, the functional nanocellulose is first loaded onto the nanocellulose to prevent migration, and then mixed with other raw materials, achieving the dual purpose of mechanically strengthening the film and preventing additive migration.

[0018] Preferably, the functional auxiliary agent is one or a combination of at least two of a UV absorber, a light stabilizer, and an antioxidant.

[0019] In the raw materials for preparing the photovoltaic encapsulation film of the present invention, the content of nanocellulose is 0.01 to 0.5 parts by mass. When the content is lower than 0.01 parts by mass, the effect of nanocellulose cannot be exerted. When the content is higher than 0.5 parts by mass, the nanocellulose is poorly dispersed and easily agglomerates, affecting the effect.

[0020] Preferably, the crosslinking agent is tert-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1 ,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl 2,5-bis(benzoylperoxy)-hexane, tert-amyl peroxycarbonate, tert-butyl peroxy-3,3,5-trimethylhexanoate, or a combination of at least two thereof, preferably tert-butyl peroxycarbonate-2-ethylhexyl carbonate, tert-amyl peroxy-2-ethylhexyl carbonate, or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, or a combination of at least two thereof.

[0021] Preferably, the auxiliary crosslinking agent is triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate. The present invention relates to a novel polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm.

[0022] Preferably, the raw materials for preparing the photovoltaic encapsulation film further include 0.01 to 1 parts by mass of a tackifier, for example, the content thereof may be 0.01 parts by mass, 0.05 parts by mass, 0.1 parts by mass, 0.5 parts by mass or 1 part by mass.

[0023] Preferably, the adhesion promoter is a silane coupling agent.

[0024] Preferably, the adhesion promoter is selected from one or a combination of at least two of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, and aminopropyltriisopropoxysilane, preferably methacryloxypropyltrimethoxysilane or vinyltrimethoxysilane.

[0025] Preferably, the raw materials for preparing the photovoltaic encapsulation film further include 0.01 to 0.2 parts by mass of an ultraviolet absorber, for example, the content thereof may be 0.01 parts by mass, 0.05 parts by mass, 0.1 parts by mass or 0.2 parts by mass.

[0026] Preferably, the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone, 2,2-tetramethylenebis(3,1-benzoxazine-4-one), 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2)-4,6-bis(1-methyl-1-phenylethyl)phenol, or a combination of at least two thereof, preferably 2-(2'-hydroxy-5-methylphenyl)benzotriazole or 2-hydroxy-4-n-octyloxybenzophenone.

[0027] Preferably, the raw materials for preparing the photovoltaic encapsulation film further include 0.01 to 0.2 parts by mass of a light stabilizer, for example, the content thereof may be 0.01 parts by mass, 0.05 parts by mass, 0.1 parts by mass or 0.2 parts by mass.

[0028] Preferably, the light stabilizer is 3,5-di-tert-butyl-4-hydroxy-benzoic acid hexadecyl ester, tris (1,2,2,6,6-pentamethyl-4-piperidinyl) phosphite, bis-2,2,6,6-tetramethylpiperidinol sebacate, bis-1-decyloxy-2,2,6,6-tetramethylpiperidin-4-ol sebacate, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, N,N'-bis Polymers of (2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine and morpholine-2,4,6-trichloro-1,3,5-triazine, 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazin-2-yl]-1,5,8,12-tetraazadodecane, poly-{[6-[(1,1,3,3-tetramethylbutyl) one or a combination of at least two of [4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2,4-diyl] [2-(2,2,6,6-tetramethylpiperidinyl)-nitro]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]}, preferably 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2,4-diyl] -yl]-1,5,8,12-tetraazadodecane, poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-nitro]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} or bis-2,2,6,6-tetramethylpiperidinol sebacate or a combination of at least two thereof.

[0029] Preferably, the thickness of the nanocellulose reinforced photovoltaic encapsulation film is 0.10 mm to 1.00 mm, for example, 0.10 mm, 0.30 mm, 0.50 mm, 0.70 mm, 0.80 mm, 0.90 mm or 1.00 mm.

[0030] On the other hand, the present invention provides a method for preparing the nanocellulose reinforced photovoltaic encapsulation film as described above, the preparation method comprising the following steps:

[0031] The required raw materials are mixed evenly, melt-extruded, and cast into a film to obtain a nanocellulose reinforced photovoltaic encapsulation film.

[0032] Preferably, the melt extrusion uses a single-screw extruder.

[0033] Preferably, the melt extrusion module temperature is set to 50-80° C., such as 50° C., 55° C., 60° C., 65° C., 70° C., 75° C. or 80° C. In the present invention, if the module temperature is set too high, the resin will crosslink and agglomerate inside the machine.

[0034] On the other hand, the present invention provides the use of the above nanocellulose reinforced photovoltaic encapsulation film in the preparation of photovoltaic modules.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The nanocellulose-reinforced photovoltaic film prepared by the present invention can significantly improve the mechanical strength of the film. The high specific surface area and special surface chemical properties of nanocellulose make it easy to form a strong chemical bond with the resin matrix, increase the cross-linking density of the resin, and improve the mechanical strength and chemical stability of the film. At the same time, the high tensile strength of nanocellulose can improve the overall strength of the film.

[0037] The nanocellulose-reinforced photovoltaic film prepared by the present invention can reduce the migration of additives to the film surface and improve the film's stability. On one hand, the high specific surface area and porous network structure of nanocellulose give it a high load capacity; on the other hand, the large number of oxygen-containing functional groups such as hydroxyl groups on the nanocellulose surface can form hydrogen bonds or chemical bonds with additives, preventing their migration. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0039] Example 1

[0040] A nanocellulose-reinforced photovoltaic encapsulation film, the preparation raw materials of which include: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Energy), 0.1 parts by mass of cellulose nanofibers (CNF), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0041] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0042] Example 2

[0043] A nanocellulose-reinforced photovoltaic encapsulation film is prepared from the following raw materials: 100 parts by mass of EVA (Hanwha Total Energy) with a VA content of 28%, 0.2 parts by mass of cellulose nanofibers (CNF), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0044] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0045] Example 3

[0046] A nanocellulose-reinforced photovoltaic encapsulation film, prepared from raw materials including: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Energy), 0.3 parts by mass of cellulose nanofibers (CNF), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0047] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0048] Example 4

[0049] A nanocellulose-reinforced photovoltaic encapsulation film is prepared from the following raw materials: 100 parts by mass of ethylene-octene copolymer (Dow Chemical, USA), 0.1 parts by mass of cellulose nanofiber (CNF), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (TBEC, Uni-Initiator (Shanghai) Co., Ltd.), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (KH-570, Evonik Degussa).

[0050] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0051] Example 5

[0052] A nanocellulose-reinforced photovoltaic encapsulation film is prepared from the following raw materials: 100 parts by mass of ethylene-octene copolymer (Dow Chemical, USA), 0.4 parts by mass of functional nanocellulose, 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570). The ratio of each component of the functional nanocellulose is as follows, in parts by mass: cellulose nanofiber: 2-hydroxy-4-n-octyloxybenzophenone: bis-2,2,6,6-tetramethylpiperidinol sebacate = 1:1:2.

[0053] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0054] Comparative Example 1:

[0055] A nanocellulose-reinforced photovoltaic encapsulation film is prepared from the following raw materials: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Energy), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0056] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0057] Comparative Example 2:

[0058] A nanocellulose-reinforced photovoltaic encapsulation film is prepared from the following raw materials: 100 parts by mass of ethylene-octene copolymer (Dow Chemical, USA), 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Unaid Initiator (Shanghai) Co., Ltd., TBEC), 1.0 parts by mass of trimethylolpropane triacrylate (TMPTA, Tianjin Tianjiao Chemical Co., Ltd.), 0.1 parts by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 parts by mass of bis-2,2,6,6-tetramethylpiperidinol sebacate (BASF, Germany, Tinuvin 770), and 0.2 parts by mass of methacryloyloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0059] The above raw materials were mixed evenly in a stirring kettle, blended and extruded through an extruder, and the extruded materials were melted and plasticized and then injected into a die head. Nanocellulose reinforced photovoltaic encapsulation film with a thickness of 0.60 mm was prepared through processes such as melt extrusion, cast film, cooling, slitting, and winding.

[0060] Comparative Example 3

[0061] The only difference from Example 1 is that the added amount of cellulose nanofiber (CNF) is 1 part by mass.

[0062] Performance testing plan:

[0063] 1. Light transmittance test:

[0064] The test sample thickness is 0.6 mm. According to the spectrophotometer method of GB / T 2410-2008, the average transmittance in the range of 380 to 1100 nm is taken.

[0065] 2. Cross-linking degree test

[0066] Sample preparation is as follows: Take a 50mm x 50mm piece of adhesive film and stack it, from bottom to top, on top of glass, non-stick film, adhesive film, non-stick film, and finally glass. Place it in a vacuum laminator for curing and crosslinking. Remove the film and cool it to room temperature in a desiccator before use. The cured film must be flat and uniform in thickness, with a crosslinking degree of at least 75%. Weigh 0.50g ± 0.01g and cut it into small pellets smaller than 3mm x 3mm. Each set of samples should contain at least three.

[0067] The test method is as follows: a. Wash and dry the stainless steel mesh bag, and weigh it as W1 (accurate to 0.001g); b. Place the prepared sample in the stainless steel mesh bag, and weigh it as W2 (accurate to 0.001g); c. Seal the mesh bag with wire, place it in a three-necked flask filled with 1 / 2 volume of xylene solution, immerse the sample in the solvent, heat it to about 140°C, and condense and reflux for 5h; d. After the reflux is completed, take out the stainless steel mesh bag, hang it to remove droplets, and place it in a vacuum oven at 140°C, dry it to constant weight; e. Take out the stainless steel mesh bag, remove the wire, and place it in a desiccator to cool to room temperature, and weigh it as W3 (accurate to 0.001g).

[0068] The calculation method is as follows: Calculate the degree of cross-linking according to the following formula and take the average value of the test results.

[0069] D=(W3-W1) / (W2-W1)*100%

[0070] Where D is the degree of cross-linking; W1 is the mass of the empty stainless steel wire mesh bag / g; W2 is the mass of the wire mesh containing the sample / g; W3 is the mass of the sample and wire mesh after extraction and drying / g.

[0071] 3. Tensile strength test:

[0072] The specimen preparation method is as follows: a. Prepare two pieces of 200mm*200mm adhesive film, one piece of glass, and one flexible backboard. Stack them in the order of glass / two pieces of adhesive film / flexible board, and place them in a vacuum laminator for curing and cross-linking. The cured sample should have a flat surface, uniform thickness, and no bubbles, and a cross-linking degree of more than 75%. b. Prepare dumbbell-shaped specimens according to the requirements of GB / T 104.3-2006 as type 5 specimens, with at least 5 samples per group.

[0073] The test method is as follows: According to the experimental method of GB / T 1040.1-2006, the tensile strength and elongation at break are tested and calculated on a tensile testing machine at a tensile speed of 100 mm / min. At least 5 specimens are tested and the average value is taken.

[0074] The test results of all samples are shown in Table 1.

[0075] Table 1 Performance test results of the embodiments and comparative examples

[0076]

[0077] As can be seen from the data in Table 1 above, compared with Examples 1, 2 and 3, the crosslinking degree of Comparative Example 1 is reduced, and the tensile strength and elongation at break are significantly reduced.

[0078] Comparing Comparative Example 2 with Examples 4 and 5, the crosslinking degree, tensile strength and elongation at break of Comparative Example 2 are significantly reduced.

[0079] In Comparative Example 3, the ratio of nanocellulose is increased by 10 times, which greatly increases the cost. In addition, since nanocellulose is difficult to disperse, the process difficulty is also increased. Although the effect of Comparative Example 3 is improved to a certain extent, the improvement is slight and the cost is significantly increased.

[0080] The applicant declares that while the present invention uses the aforementioned embodiments to illustrate the nanocellulose-reinforced photovoltaic encapsulation film, its preparation method, and its application, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A nanocellulose reinforced photovoltaic encapsulation film, characterized in that: The raw materials for preparing the photovoltaic encapsulation film include the following components in parts by mass: 100 parts by mass of a resin matrix, 0.01 to 0.5 parts by mass of nanocellulose or functional nanocellulose, 0.05 to 2 parts by mass of a crosslinking agent, and 0.05 to 5 parts by mass of an auxiliary crosslinking agent.

2. The nanocellulose reinforced photovoltaic encapsulation film according to claim 1, characterized in that The resin matrix is one or a combination of at least two of ethylene-vinyl acetate copolymer, ethylene copolymer, propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer, preferably ethylene-vinyl acetate copolymer or ethylene-octene copolymer; Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 10-33%, preferably 28-33%; the melt index is 10-43 g / 10 min, preferably 15-25 g / 10 min; Preferably, the melt index of the ethylene-octene copolymer is 3 to 30 g / 10 min, preferably 5 to 15 g / 10 min.

3. The nanocellulose reinforced photovoltaic encapsulation film according to claim 1 or 2, characterized in that: The nanocellulose is a nanofiber material made by processing plant fibers, including cellulose nanofibers and cellulose nanocrystals, preferably cellulose nanofibers; Preferably, the solid content of the cellulose nanofibers is greater than 95%, the fiber diameter is 3 to 100 nm, and the fiber length is 0.2 to 10 μm; Preferably, the functional nanocellulose is nanocellulose loaded with a functional additive; Preferably, the mass ratio of the functional additive to the nanocellulose is 0.2:1 to 10:1; Preferably, the functional auxiliary agent is one or a combination of at least two of a UV absorber, a light stabilizer or an antioxidant.

4. The nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 3, characterized in that: The crosslinking agent is tert-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1,1 - one or a combination of at least two of bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl 2,5-bis(benzoylperoxy)-hexane, tert-amyl peroxycarbonate, and tert-butyl peroxy-3,3,5-trimethylhexanoate, preferably one or a combination of at least two of tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxy-2-ethylhexyl carbonate, or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane; Preferably, the auxiliary crosslinking agent is triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate. The present invention relates to a novel polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm. The present invention relates to a polyol having a molecular weight of 400 nm and a molecular weight of 400 nm.

5. The nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 4, characterized in that: The raw materials for preparing the photovoltaic encapsulation film also include 0.01 to 1 parts by mass of a tackifier; Preferably, the tackifier is a silane coupling agent; Preferably, the adhesion promoter is selected from one or a combination of at least two of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, and aminopropyltriisopropoxysilane, preferably methacryloxypropyltrimethoxysilane or vinyltrimethoxysilane.

6. The nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 5, characterized in that: The raw materials for preparing the photovoltaic encapsulation film also include 0.01 to 0.2 parts by mass of an ultraviolet absorber; Preferably, the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone, 2,2-tetramethylenebis(3,1-benzoxazine-4-one), 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2)-4,6-bis(1-methyl-1-phenylethyl)phenol, or a combination of at least two thereof, preferably 2-(2'-hydroxy-5-methylphenyl)benzotriazole or 2-hydroxy-4-n-octyloxybenzophenone.

7. The nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 6, characterized in that: The raw materials for preparing the photovoltaic encapsulation film also include 0.01 to 0.2 parts by mass of a light stabilizer.

8. The nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 7, characterized in that: The light stabilizer is 3,5-di-tert-butyl-4-hydroxy-benzoic acid hexadecyl ester, tris (1,2,2,6,6-pentamethyl-4-piperidinyl) phosphite, bis-2,2,6,6-tetramethylpiperidinol sebacate, bis-1-decyloxy-2,2,6,6-tetramethylpiperidin-4-ol sebacate, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, N,N'-bis (2, Polymer of 2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine and morpholine-2,4,6-trichloro-1,3,5-triazine, 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazin-2-yl]-1,5,8,12-tetraazadodecane, poly-{[6-[(1,1,3,3-tetramethylbutyl) -imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-nitro]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} or a combination of at least two thereof, preferably 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2,4-diyl] one or a combination of at least two of: poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexylidene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} or bis-2,2,6,6-tetramethylpiperidinol sebacate; Preferably, the thickness of the nanocellulose reinforced photovoltaic encapsulation film is 0.10 mm to 1.00 mm.

9. The method for preparing the nanocellulose-enhanced photovoltaic encapsulation film according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: The required raw materials are mixed evenly, melt-extruded, and cast into a film to obtain a nanocellulose reinforced photovoltaic encapsulation film; Preferably, the melt extrusion uses a single screw extruder; Preferably, the module temperature of the melt extrusion is set to 50-80°C.

10. Use of the nanocellulose reinforced photovoltaic encapsulation film according to any one of claims 1 to 8 in the preparation of photovoltaic modules.

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