Self-healing polyolefin encapsulation adhesive film and method of making same

Abstract

A self-healing polyolefin encapsulation adhesive film and a preparation method thereof, raw materials including the following components in mass fractions: polyolefin copolymer, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer, and tackifier. The encapsulation adhesive film introduces a dynamic borate ester bond with reversible properties into the polyolefin adhesive film material, constructs a crosslinking network structure that can be topologically rearranged, and endows the encapsulation adhesive film for photovoltaic modules with excellent adhesion performance and self-healing efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solar photovoltaic module encapsulation, in particular to a preparation method of a self-healing polyolefin encapsulation adhesive film. BACKGROUND

[0002] Currently, the main encapsulation material used in the field of solar photovoltaic modules is EVA (ethylene-vinyl acetate copolymer) adhesive film. However, EVA adhesive film is prone to aging and decomposition under the influence of light and heat during use, which not only reduces the light transmittance, but also causes the adhesive force of the adhesive film to decrease, thereby reducing the power of the photovoltaic module and shortening its service life. Compared with EVA adhesive film, POE (polyolefin) encapsulation adhesive film has shown broad prospects in the application of photovoltaic industry encapsulation materials due to its excellent water vapor barrier performance, weather resistance and anti-aging performance. These characteristics make POE an ideal choice to replace EVA and improve the encapsulation quality and service life of solar cells.

[0003] As a battery encapsulation material, POE adhesive film is still subject to challenges from multiple aspects in terms of its surface and internal structure under outdoor environments and harsh working conditions. First, long-term exposure to strong sunlight can accelerate the aging process of the material, leading to molecular chain breakage and the initiation of cracks. Second, oxidation cannot be ignored, as oxygen in the air reacts with unsaturated bonds in the material, damaging its chemical structure and leading to a decline in material performance and the generation of cracks. In addition, continuous external load can also cause high stress in local areas of the material, promoting the formation and propagation of cracks. The combined effects of the above factors will inevitably result in cracks or damage to the POE adhesive film during the long-term service of photovoltaic modules. By designing the molecular structure, self-healing ability can be imparted, which means that when the material has a small crack, a special mechanism within the cross-linked network can automatically trigger under external stimuli, repairing the damage and restoring the integrity and performance of the material. Good adhesion allows the material to better resist peeling and falling off when subjected to external forces, maintaining the stability of the structure. This not only significantly improves the durability and reliability of the material, reducing the replacement and maintenance of photovoltaic modules due to cracks in the encapsulation adhesive film, but also effectively prolongs its service life.

[0004] Most of the existing technical solutions add nanoparticles, microcapsules, external coatings, etc. to the material to achieve the function of material self-healing through external self-repairing means.

[0005] CN202411418686.6 discloses a cement mortar for road repair and a preparation method thereof, a multi-hydrogen bond chain extender is first prepared, and then a water-based polyurethane emulsion and a water-based epoxy emulsion are prepared; the water-based polyurethane emulsion and the water-based epoxy emulsion are mixed, and then nano titanium dioxide and a silane coupling agent are added to prepare a polymer enhanced emulsion; silicate cement, fast hardening sulphoaluminate cement, fly ash, the polymer enhanced emulsion, a curing agent, water, a defoaming agent and a water reducing agent are mixed and stirred uniformly to prepare the cement mortar for road repair, that is, a material with self-repairing performance is obtained by adding nano-particle materials.

[0006] CN202411180760.5 discloses a preparation method and application of an intelligent magnetic targeting hyperbranched polyurethane self-healing microcapsule, which is composed of a light-sensitive microcapsule capable of magnetic targeting distribution and an epoxy resin.

[0007] CN202222853645.2 discloses a tape with a self-repairing function, which comprises a high-molecular base film, an adhesive layer coated on the base film, and a self-repairing functional layer coated on the base film.

[0008] CN201810329859.5 discloses a polyolefin packaging adhesive film with a self-repairing function, which comprises, in mass fraction, 80-100 parts of a packaging adhesive film substrate POE, 8-15 parts of a supramolecular self-healing functional compound, 0.5-2.0 parts of a crosslinking agent, 0.2-2.0 parts of an antioxidant, 0.02-1.0 parts of an ultraviolet light stabilizer, and 0.5-2.0 parts of an adhesion promoter, wherein the supramolecular self-healing functional compound is formed by self-polymerization of an olefin amide-containing polysiloxane or poly-silsesquioxane monomer and has a crosslinked macromolecular structure.

[0009] However, the above-mentioned methods have some obvious defects: 1. The content of external repair agent is limited, and the repair effect will gradually decrease with the increase of repair times until the repair agent is exhausted; 2. The dispersibility and compatibility of the repair agent are difficult to guarantee, and phenomena such as agglomeration and delamination are likely to occur, which will affect the normal use of the material if the uniformity of the material is poor; 3. The external repair material often needs specific trigger conditions to heal, which increases the difficulty and cost of repair and reduces the repair efficiency.

[0010] Therefore, there is an urgent need to develop a POE adhesive film that can be self-healed by intrinsic self-repairing means and has high adhesion (>120N / cm).

[0011] In view of this, the present application is proposed. SUMMARY

[0012] In order to solve the problem that the polyolefin adhesive film is prone to cracking, one of the purposes of the present application is to provide a preparation method of a self-healing functional monomer, which comprises the following steps: uniformly mixing 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] to obtain a self-healing functional monomer after polymerization. The self-healing functional monomer can be introduced into the crosslinked network of the material through grafting reaction.

[0013] The second purpose of the present application is to provide a self-healing packaging adhesive film, which introduces reversible borate ester bonds into the adhesive film material to construct a three-dimensional body-shaped crosslinked network structure that can be dynamically rearranged, thereby endowing the material with the characteristics of internal repair. The raw materials for preparing the packaging adhesive film include the following components in mass fraction: 90-110 parts of polyolefin copolymer POE, 0.5-5 parts of self-healing functional monomer, 0.2-3 parts of crosslinking agent, 0.2-3 parts of antioxidant, 0.2-3 parts of light stabilizer and 0.2-3 parts of tackifier.

[0014] The third purpose of the present application is to provide a preparation method of a packaging adhesive film, which specifically comprises the following steps: mixing polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier to obtain a mixture after uniform stirring; and extruding and casting the mixture to obtain the packaging adhesive film.

[0015] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0016] In the first aspect, the present application provides a self-healing functional monomer for polyolefin adhesive film, and the raw materials for preparing the self-healing functional monomer include: 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane], which are reacted in a weak alkaline solution to obtain a self-healing functional monomer.

[0017] wherein 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione can be commercially purchased or prepared by itself, the preparation method is: under stirring conditions, 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborinane (CAS No. 342002-80-6) and N-phenylmaleimide (CAS No. 941-69-5) are mixed in a certain molar ratio and heated to react, after the reaction is completed, the product is dried at 120°C for 3h to remove free dioxaborinane to obtain 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione. The molar ratio of the 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborinane and N-phenylmaleimide is preferably 2:1, the reaction temperature is preferably 80°C, and the reaction time is preferably 3h.

[0018] wherein 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] can be commercially purchased or prepared by itself, the preparation method is: under stirring conditions, 2-(4-biphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborinane (CAS No. 144432-80-4) and 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborinane (CAS No. 342002-80-6) are mixed in a certain molar ratio and heated to react, after the reaction is completed, the product is dried at 120°C for 3h to remove free dioxaborinane to obtain 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane]. The molar ratio of the 2-(4-biphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborinane and 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborinane is preferably 1:1, the reaction temperature is preferably 95°C, and the reaction time is preferably 2h.

[0019] Further, the molar ratio of the 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] is (0.9-1.2):1, for example, it can be 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, etc.

[0020] Further, the weak alkaline solution is sodium bicarbonate solution, potassium bicarbonate solution, ammonium carbonate solution, preferably sodium bicarbonate solution.

[0021] The application also provides a preparation method of a self-healing functional monomer for a polyolefin adhesive film, comprising: under stirring, adding 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] into a weak alkaline solution according to a molar ratio of (0.9-1.2):1, and performing an exchange reaction by heating to obtain the self-healing functional monomer.

[0022] Further, the weak alkaline solution is a sodium bicarbonate solution, a potassium bicarbonate solution, an ammonium carbonate solution, and preferably a sodium bicarbonate solution.

[0023] Further, the weak alkaline solution has a molar concentration of (0.3-0.6) mol / L, for example, 0.3 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, etc.

[0024] Further, the sodium bicarbonate solution has a molar concentration of (0.3-0.6) mol / L, for example, 0.3 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, etc.

[0025] Further, the exchange reaction has a temperature of (60-90) °C, for example, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, etc.

[0026] Further, the exchange reaction has a time of (2-5) h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc.

[0027] Further, after the exchange reaction, an acid washing is performed, and then drying is performed to remove salt impurities to obtain the self-healing functional monomer.

[0028] Further, a dilute hydrochloric acid solution is added during the acid washing, and the dilute hydrochloric acid solution has a molar concentration of (0.5-1) mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc.

[0029] Further, the drying process has a temperature of 100-140 °C, for example, 110 °C, 120 °C, 125 °C, 130 °C, etc.

[0030] Further, the drying process has a time of 1-5 h, for example, 2 h, 3 h, 4 h, etc.

[0031] In a second aspect, the present application provides a packaging adhesive film, raw materials for preparing the packaging adhesive film include the following components in mass fraction: 90-110 parts of polyolefin copolymer, 0.5-5 parts of self-healing functional monomer, 0.2-3 parts of crosslinking agent, 0.2-3 parts of antioxidant, 0.2-3 parts of light stabilizer and 0.2-3 parts of tackifier.

[0032] Further, the content of the polyolefin copolymer in the raw materials for preparing the packaging adhesive film is 90-110 parts, for example, it can be 90 parts, 95 parts, 100 parts, 105 parts, 110 parts, etc., and preferably 100 parts.

[0033] Further, the content of the self-healing functional monomer in the raw materials for preparing the packaging adhesive film is 0.5-5 parts, for example, it can be 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc., and preferably 1.5-3 parts.

[0034] Further, the content of the crosslinking agent in the raw materials for preparing the packaging adhesive film is 0.2-3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., and preferably 0.6-1.8 parts.

[0035] Further, the content of the antioxidant in the raw materials for preparing the packaging adhesive film is 0.2-3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., and preferably 0.2-1.5 parts.

[0036] Further, the content of the light stabilizer in the raw materials for preparing the packaging adhesive film is 0.2-3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., and preferably 0.2-1 part.

[0037] Further, the content of the tackifier in the raw materials for preparing the packaging adhesive film is 0.2-3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., and preferably 0.6-2 parts.

[0038] Further, the polyolefin copolymer is any one or a combination of at least two of ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-hexene copolymer, ethylene-heptene copolymer and ethylene-nonene copolymer.

[0039] Further, the cross-linking agent is any one of or a combination of at least two of dibenzoyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexyl carbonate, dicumyl peroxide, t-butyl peroxy-iso-propyl carbonate, ethyl-3,3-di(t-butylperoxy) butyrate, t-amyl peroxybenzoate, t-butyl peroxy-2-ethylhexyl carbonate.

[0040] Further, the antioxidant is any one of or a combination of at least two of tris(2,4-di-t-butylphenyl) phosphite, tetra[β-(3,5-di-t-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, tetra-(4-hydroxy-3,5-butylphenyl propionic acid) pentaerythritol ester, β-(3,5-di-t-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, distearyl pentaerythritol diphosphite, N,N'-1,6-hexanediyl bis(3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide, 2,6-di-t-butyl-p-cresol, pentaerythritol bisphosphite dioctadecyl ester.

[0041] Further, the light stabilizer is any one of or a combination of at least two of (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 4-hydroxybenzoic acid-2,4-di-t-butylphenyl ester, 3,5-di-t-butyl-4-hydroxybenzoic acid-2,4-di-t-butylphenyl ester, 2-hydroxy-4-benzoyloxybenzophenone, [2-hydroxy-4(octyloxy)phenyl] phenyl ketone, 2-(2-hydroxy-3,5-di-t-amylphenyl) benzotriazole.

[0042] Further, the adhesion promoter is any one of or a combination of at least two of 3-aminopropyltrimethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, methacryloxypropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane.

[0043] Further, the polyolefin copolymer, the self-healing functional monomer, the cross-linking agent, the antioxidant, the light stabilizer, and the adhesion promoter are mixed to obtain a mixture after being uniformly stirred; and the mixture is extruded and cast to obtain the encapsulation adhesive film.

[0044] In a third aspect, the present application provides a preparation method of an encapsulation adhesive film, which specifically comprises the following steps: mixing a polyolefin copolymer, a self-healing functional monomer, a cross-linking agent, an antioxidant, a light stabilizer, and an adhesion promoter to obtain a mixture after being uniformly stirred; and extruding and casting the mixture to obtain the encapsulation adhesive film.

[0045] Further, the components are in mass parts: polyolefin copolymer 90-110 parts, self-healing functional monomer 0.5-5 parts, crosslinking agent 0.2-3 parts, antioxidant 0.2-3 parts, light stabilizer 0.2-3 parts and tackifier 0.2-3 parts.

[0046] Further, the stirring speed is 250-500 r / min, for example, it can be 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, etc.; the stirring time is 25-50 min, for example, it can be 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, etc.

[0047] Further, the extrusion temperature is 100-130 DEG C, for example, it can be 100 DEG C, 105 DEG C, 110 DEG C, 115 DEG C, 120 DEG C, 125 DEG C, 130 DEG C, etc.; the screw speed is 50-80 r / min, for example, it can be 50 r / min, 55 r / min, 60 r / min, 65 r / min, 70 r / min, 75 r / min, 80 r / min, etc.

[0048] Further, the casting temperature is 120-130 DEG C, for example, it can be 120 DEG C, 122 DEG C, 124 DEG C, 126 DEG C, 128 DEG C, 130 DEG C, etc.; the winding speed is 5-10 m / min, for example, it can be 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min, 10 m / min, etc.

[0049] The application also provides an application of a self-healing functional monomer in self-repairing of a polyolefin adhesive film, wherein the self-healing functional monomer is introduced into a polyolefin copolymer molecular chain.

[0050] The application also provides an application of a self-healing packaging adhesive film, which is applied in the field of solar cell packaging.

[0051] The application provides a preparation method of a self-healing POE packaging adhesive film, which can be applied to the field of solar cell packaging. The self-healing functional monomer is introduced into the polyolefin copolymer POE molecular chain by means of reactive extrusion grafting copolymerization. The borate ester bond has dynamic reversibility under certain conditions, and therefore it can improve the specific performance of the adhesive film material. On the one hand, the borate ester bond can quickly convert between fracture and formation, and this dynamic behavior enables the material to more easily adjust its molecular structure and spatial configuration when subjected to external force, thereby exhibiting higher flexibility. This endows the POE packaging adhesive film in the lamination process with stronger flowability, and further enables the film to form a closer combination with the glass, so as to achieve a higher adhesive strength. On the other hand, thanks to the unique properties of the borate ester bond, the damaged part of the material can realize self-healing through the structural rearrangement of the three-dimensional crosslinked network. In the dynamic exchange process, the crosslinking density and structural integrity of the network remain unchanged, which endows the POE adhesive film as a packaging material with excellent intrinsic self-repairing ability and reprocessing performance.

[0052] Compared with the prior art, the self-healing POE packaging adhesive film provided by the application has the following advantages:

[0053] (1) The self-healing functional monomer with a borate ester bond and a diboronane structure is introduced into the network structure of the adhesive film, which not only improves the chemical stability of the adhesive film material, but also makes the adhesive film have stronger flowability, so that the adhesive film can form a closer combination with the glass during the lamination process, and the adhesive strength is greatly improved, and the adhesive film can better resist peeling and falling off under extreme conditions.

[0054] (2) The borate ester bond with reversible properties is introduced into the molecular chain to construct a three-dimensional crosslinked network with dynamic configuration. After the adhesive film is damaged, the movement of the molecular chain causes the dissociated borate ester bonds to collide with each other and recombine, so that the complete network structure is formed again, which macroscopically appears as the healing of the damage, and the process can be carried out at room temperature. The POE packaging adhesive film can realize multiple, efficient and special-condition-free healing through intrinsic self-repairing means, which has practical value for reducing the difficulty and cost of repairing the packaging assembly and prolonging the service life of the packaging assembly. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The chemical structure and infrared spectrum of the self-healing functional monomer are shown in the figure.

[0056] Figure 2 The infrared spectrum of the packaging adhesive film provided for Example 1 and Comparative Example 1 is shown in the figure.

[0057] Figure 3 The electron microscope graph of the scratch self-healing of the packaging adhesive film provided for Example 2 is shown in the figure, and different scratch widths are used for self-healing test. DETAILED DESCRIPTION

[0058] In order to make the structure of the present application more understandable and the function features and advantages achieved more comprehensible, the technical solutions will be described in detail and completely below in combination with the preferred embodiments of the present application.

[0059] Embodiment 1

[0060] (1) Preparation of self-healing functional monomer

[0061] The present embodiment provides a self-healing functional monomer, and a preparation method thereof is as follows: under stirring, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added into a 0.3 mol / L sodium bicarbonate solution according to a molar ratio of 0.9:1, and an exchange reaction is carried out at 60℃ for 5h. After the reaction is completed, the above mixture is added into a 0.5 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120℃ for 3h to remove the solvent, and finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0062] (2) Preparation of polyolefin packaging adhesive film

[0063] The present embodiment provides a preparation method of a self-healing polyolefin packaging adhesive film, and the preparation raw materials of the packaging adhesive film include the following components in mass fraction:

[0064] Polyolefin copolymer Ethylene-propylene copolymer 100 parts Crosslinking agent Dibenzoyl peroxide 0.6 parts Antioxidant Tris(2,4-di-tert-butylphenyl) phosphite 1.5 parts Light stabilizer (2,2,6,6-tetramethyl-4-piperidinyl) sebacate 0.2 parts Tackifier 3-aminopropyltrimethoxysilane 2 parts Self-healing functional monomer The self-healing functional monomer provided in Example 1 1.5 parts

[0065] The packaging adhesive film is prepared according to the following steps: mixing the polyolefin copolymer POE, the self-healing functional monomer, the crosslinking agent, the antioxidant, the light stabilizer and the tackifier, and stirring in a mixing kettle at a rotating speed of 250r / min for 50min to obtain a mixture; and extruding and granulating the mixture at 100℃ and a screw rotating speed of 50r / min. Casting and rolling the granules at 120℃ and a rolling speed of 5m / min to obtain the packaging adhesive film.

[0066] Embodiment 2

[0067] (1) Preparation of self-healing functional monomer

[0068] The self-healing functional monomer is prepared by the following method: under stirring, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added into 0.4 mol / L sodium bicarbonate solution at a molar ratio of 1:1, and exchange reaction is carried out at 70°C for 4h. After the reaction is completed, the above mixture is added into 0.6 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120°C for 3h to remove the solvent. Finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0069] (2) Preparation of the polyolefin encapsulating adhesive film

[0070]

[0071] The encapsulating adhesive film is prepared by the following steps: polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier are mixed to obtain a mixture after stirring in a mixing kettle at a rotating speed of 300r / min for 45min; the mixture is extruded and granulated under the conditions of 110°C and screw rotating speed of 60r / min. The granules are cast and rolled under the conditions of 122°C and rolling speed of 6m / min to obtain the encapsulating adhesive film.

[0072] Example 3

[0073] (1) Preparation of the self-healing functional monomer

[0074] The self-healing functional monomer is prepared by the following method: under stirring, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added into 0.4 mol / L sodium bicarbonate solution at a molar ratio of 1:1, and exchange reaction is carried out at 70°C for 4h. After the reaction is completed, the above mixture is added into 0.6 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120°C for 3h to remove the solvent. Finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0075] (2) Preparation of the polyolefin encapsulating adhesive film

[0076]

[0077] The packaging adhesive film is prepared by the following steps: mixing polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier, and placing them in a mixing kettle to stir at a speed of 350 r / min for 40 min to obtain a mixture; the mixture is extruded and granulated at 115℃ and a screw speed of 65 r / min. The granules are cast and rolled at 124℃ and a winding speed of 7 m / min to obtain the packaging adhesive film.

[0078] Example 4

[0079] (1) Preparation of self-healing functional monomer

[0080] The self-healing functional monomer is prepared by the following method: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added to a 0.5 mol / L sodium bicarbonate solution at a molar ratio of 1.1:1, and the exchange reaction is carried out at 80℃ for 3h. After the reaction is completed, the above mixture is added to a 0.8 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120℃ for 3h to remove the solvent. Finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0081] (2) Preparation of polyolefin packaging adhesive film

[0082]

[0083]

[0084] The packaging adhesive film is prepared by the following steps: mixing polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier, and placing them in a mixing kettle to stir at a speed of 400 r / min for 35 min to obtain a mixture; the mixture is extruded and granulated at 120℃ and a screw speed of 70 r / min. The granules are cast and rolled at 126℃ and a winding speed of 8 m / min to obtain the packaging adhesive film.

[0085] Example 5

[0086] (1) Preparation of self-healing functional monomer

[0087] The self-healing functional monomer is prepared by the following method: under stirring, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added into a 0.55 mol / L sodium bicarbonate solution at a molar ratio of 1.15:1, and exchange reaction is carried out at 85°C for 2.5 hours. After the reaction is completed, the above mixture is added into a 0.9 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120°C for 3 hours to remove the solvent. Finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0088] (2) Preparation of the polyolefin encapsulating adhesive film

[0089]

[0090]

[0091] The encapsulating adhesive film is prepared by the following steps: mixing the polyolefin copolymer POE, the self-healing functional monomer, the crosslinking agent, the antioxidant, the light stabilizer and the tackifier, and stirring in a mixing kettle at a speed of 450 r / min for 30 minutes to obtain a mixture; and extruding and granulating the mixture at 125°C and a screw speed of 75 r / min. The granules are cast and rolled at 128°C and a winding speed of 9 m / min to obtain the encapsulating adhesive film.

[0092] Example 6

[0093] (1) Preparation of the self-healing functional monomer

[0094] The self-healing functional monomer is prepared by the following method: under stirring, 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added into a 0.55 mol / L sodium bicarbonate solution at a molar ratio of 1.15:1, and exchange reaction is carried out at 85°C for 2.5 hours. After the reaction is completed, the above mixture is added into a 0.9 mol / L dilute hydrochloric acid solution for acid washing, and then dried at 120°C for 3 hours to remove the solvent. Finally, the salt impurities are filtered out to obtain the self-healing functional monomer.

[0095] (2) Preparation of the polyolefin encapsulating adhesive film

[0096]

[0097] The encapsulation adhesive film is prepared by the following steps: mixing polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier, placing in a mixing kettle and stirring at a speed of 500 r / min for 25 min to obtain a mixture; extruding and granulating the mixture at 130℃ and a screw speed of 80 r / min. Casting and winding the granules at 130℃ and a winding speed of 10 m / min to obtain the encapsulation adhesive film.

[0098] Comparative Example 1

[0099] The preparation method of Example 1 is repeated according to the specified proportions of each component, but the self-healing functional monomer is not added.

[0100] Comparative Example 2

[0101] The preparation method of Example 2 is repeated according to the specified proportions of each component, but the self-healing functional monomer is not added.

[0102] Comparative Example 3

[0103] The preparation method of Example 3 is repeated according to the specified proportions of each component, but the self-healing functional monomer is not added.

[0104] Comparative Example 4

[0105] The preparation method of Example 4 is repeated according to the specified proportions of each component, but the self-healing functional monomer is not added.

[0106] Test 1: Infrared test.

[0107] Test instrument: FTIR Invenio R Fourier transform infrared spectrometer.

[0108] Test sample: self-healing functional monomer and encapsulation adhesive film provided by Example 1, encapsulation adhesive film provided by Comparative Example 1.

[0109] Test method: The self-healing functional monomer does not need to be treated and is directly tested. The single-layer encapsulation adhesive film is laminated: vacuum time 390 s, lamination time 530 s, lamination temperature 145℃. The laminated encapsulation adhesive film is tested.

[0110] Test 2: Adhesion test.

[0111] Test instrument: Zwick Roell universal testing machine.

[0112] Test sample: encapsulation adhesive film provided by Examples 1-6, encapsulation adhesive film provided by Comparative Examples 1-4.

[0113] Test method: Laminated according to the structure of glass / high temperature cloth / encapsulation adhesive film / encapsulation adhesive film / backboard: vacuum time 390 s, laminating time 530 s, laminating temperature 145℃. The adhesion of the laminated sample was tested according to the test standard GB / T2792-1998.

[0114] Test three: self-healing efficiency test.

[0115] Test instrument: BX 51TF Instec H601 hot stage polarizing microscope.

[0116] Test sample: encapsulation adhesive film provided by examples 1-6, encapsulation adhesive film provided by comparative examples 1-4.

[0117] Test method: Double-layer encapsulation adhesive film was laminated: vacuum time 390 s, laminating time 530 s, laminating temperature 145℃. A scalpel was used to make a scratch on the surface of the encapsulation adhesive film, which was placed on the stage and observed for changes in scratch width at room temperature, i.e. self-repairing behavior. The scratch width at the beginning of observation was recorded as the initial scratch width. When the scratch width no longer changed, the scratch width at this time was recorded as the healed scratch width. The self-healing efficiency of the encapsulation adhesive film was calculated as follows:

[0118] Self-healing efficiency = (1-healed scratch width / initial scratch width) x 100%

[0119] The structure of the self-healing functional monomer provided by example 1 was characterized by infrared spectroscopy, and the spectrum is shown in Figure 1 The characteristic peak at 1730 cm -1 corresponds to the carbonyl group (C=O) in the structure of 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione; the characteristic peak at 1517 cm -1 is attributed to the benzene ring (C=O) in the structure of 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane]; and the characteristic peak at 1152 cm -1 is derived from the boronate ester bond (B-O-C) formed by the exchange reaction of the two. The above analysis shows that the effective synthesis of the self-healing functional monomer.

[0120] The encapsulation adhesive films provided by example 1 and comparative example 1 were characterized by infrared spectroscopy, and the spectrum is shown in Figure 2 Compared with comparative example 1, the spectrum of example 1 shows a clear characteristic peak of boronate ester bond (B-O-C) at 1152 cm -1 This indicates that through the means of graft copolymerization, the dioxaborinane structure in the self-healing functional monomer is introduced into the crosslinked network of the polyolefin copolymer.

[0121] The adhesion and self-repairing performance tests were conducted on the encapsulation adhesive films provided by Examples 1-6 and Comparative Examples 1-4, and the test results are shown in Table 1.

[0122] Table 1:

[0123]

[0124] From the above test results, it can be concluded that the encapsulation adhesive films provided by Examples 1-6 have higher adhesion between the film and the glass (>120 N / cm), and the self-healing efficiency is significantly higher than that of the adhesive films provided by Comparative Examples 1-4 in the scratch repair test at room temperature, and the self-healing efficiency is higher than 95%. As shown in Table 1, the self-repairing test of the encapsulation adhesive film provided by Example 2 was conducted at different scratch widths, and the self-repairing efficiency can be as high as 100%. The above analysis shows that the introduction of borate ester bond can effectively improve the adhesion and self-healing performance of the polyolefin copolymer. The POE encapsulation adhesive film provided by the present application can meet the needs of improving the utilization rate of photovoltaic modules. Figure 3

[0125] The above description is only the preferred embodiment of the present application, and is not intended to limit the protection scope of the present application. Any equivalent changes and modifications made according to the content of the present application are included in the patent scope of the present application.​

Claims

1. A self-healing functional monomer for a polyolefin tape, a raw material for the self-healing functional monomer comprising: 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are reacted in a weak alkaline solution to obtain a self-healing functional monomer, the structure of which is as follows:

2. The self-healing functional monomer according to claim 1, characterized in that: The molar ratio of 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] is (0.9-1.2):

1.

3. The self-healing functional monomer according to claim 1, characterized in that: The weak alkaline solution is sodium bicarbonate solution, potassium bicarbonate solution, or ammonium carbonate solution.

4. The method of claim 1-3, wherein 1-[(2-phenyl-1,3,2-dioxaborinan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborinane] are added to a weak alkaline solution in a molar ratio of (0.9-1.2):1 under stirring, and an exchange reaction is carried out by heating to obtain a self-healing functional monomer.

5. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: The molar concentration of the weak alkaline solution is (0.3-0.6) mol / L.

6. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: The exchange reaction is carried out at a temperature of (60-90) °C.

7. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: The exchange reaction is carried out for a time of (2-5) h.

8. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: After the exchange reaction, an acid washing is carried out, and the self-healing functional monomer is obtained after drying and removal of salt impurities.

9. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: During the acid washing, a dilute hydrochloric acid solution is added, and the molar concentration of the dilute hydrochloric acid solution is (0.5-1) mol / L.

10. An encapsulating adhesive film, the preparation of which comprises the following components in mass parts: 90-110 parts of a polyolefin copolymer, 0.5-5 parts of the self-healing functional monomer of claim 1-3 or prepared by the method of claim 4-9, 0.2-3 parts of a crosslinking agent, 0.2-3 parts of an antioxidant, 0.2-3 parts of a light stabilizer, and 0.2-3 parts of an adhesion promoter.

11. The encapsulation film according to claim 10, wherein, The polyolefin copolymer is any one or a combination of at least two of ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-hexene copolymer, ethylene-heptene copolymer, and ethylene-nonene copolymer.

12. The encapsulation film of claim 10, wherein, The crosslinking agent is any one or a combination of at least two of dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl carbonate, dicumyl peroxide, tert-butyl peroxy-isopropyl carbonate, ethyl-3,3-di(tert-butylperoxy)butyrate, tert-amyl perbenzoate, and tert-butyl peroxy-2-ethylhexyl carbonate.

13. The encapsulation film of claim 10, wherein, The antioxidant is any one of tris(2,4-di-tert-butylphenyl)phosphite, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, tetra-(4-hydroxy-3,5-butylphenyl propionic acid) pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester, distearyl pentaerythritol diphosphite, N,N'-1,6-hexanediylbis(3,5-di(1,1-dimethylethyl)-4-hydroxybenzene propanoyl, 2,6-di-tert-butyl-p-cresol, pentaerythritol bisphosphite dioctadecyl ester or a combination of at least two thereof.

14. The encapsulation film of claim 10, wherein, The light stabilizer is any one of (2,2,6,6-tetramethyl-4-piperidyl)sebacate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 4-hydroxybenzoic acid-2,4-di-tert-butylphenyl ester, 3,5 di-tert-butyl-4-hydroxybenzoic acid-2,4-di-tert-butylphenyl ester, 2-hydroxy-4-benzoyloxybenzophenone, [2-hydroxy-4(octyloxy)phenyl]phenyl ketone, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole or a combination of at least two thereof.

15. The encapsulation film of claim 10, wherein, The adhesion promoter is any one of 3-aminopropyltrimethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane or a combination of at least two thereof.

16. The encapsulation film of claim 10, wherein, The polyolefin copolymer, the self-healing functional monomer, the crosslinking agent, the antioxidant, the light stabilizer and the adhesion promoter are mixed to obtain a mixture after being uniformly stirred; the mixture is extruded and cast to obtain the encapsulation adhesive film.

17. A method of making the encapsulation film of any one of claims 10-16, comprising the steps of: The polyolefin copolymer, the self-healing functional monomer, the crosslinking agent, the antioxidant, the light stabilizer and the adhesion promoter are mixed to obtain a mixture after being uniformly stirred; the mixture is extruded and cast to obtain the encapsulation adhesive film.

18. The method for preparing the encapsulating film according to claim 17, characterized in that, The temperature of the extrusion is 100-130°C, and the screw rotation speed is 50-80 r / min.

19. Application of a self-healing functional monomer in self-repairing of a polyolefin adhesive film, wherein the self-healing functional monomer is the self-healing functional monomer of any one of claims 1-3 or the self-healing functional monomer prepared by the preparation method of any one of claims 4-9, and the self-healing functional monomer is introduced into a polyolefin copolymer molecular chain.

20. Application of a self-healing encapsulation adhesive film, wherein the encapsulation adhesive film is the encapsulation adhesive film of any one of claims 10-16 or the encapsulation adhesive film obtained by the preparation method of any one of claims 17-18, and the encapsulation adhesive film is applied in the field of solar cell encapsulation.

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