Self-healing polyolefin packaging adhesive film and preparation method thereof

Abstract

The invention discloses a self-healing polyolefin packaging adhesive film and a preparation method thereof. The self-healing polyolefin packaging adhesive film is prepared from the following raw materials in parts by mass: a polyolefin copolymer, a self-healing functional monomer, a cross-linking agent, an antioxidant, a light stabilizer and a tackifier. According to the packaging adhesive film, dynamic borate bonds with reversible properties are introduced into a polyolefin adhesive film material to construct a topologically rearranged cross-linked network structure, so that the packaging adhesive film for the photovoltaic module is endowed with excellent adhesion performance and self-healing efficiency.

Description

Technical Field

[0001] The invention relates to the field of solar photovoltaic component packaging, and in particular to a method for preparing a self-healing polyolefin packaging film. Background Art

[0002] At present, EVA (ethylene-vinyl acetate copolymer) film is mainly used in the field of solar module encapsulation. However, EVA film is easily affected by light and heat and decomposes during use, which not only reduces the light transmittance, but also causes the adhesion of the film to decrease, thereby reducing the power of photovoltaic modules and shortening their service life. Compared with EVA film, POE (polyolefin) encapsulation 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, improve the quality of solar cell encapsulation and extend the service life.

[0003] As a battery packaging material, the surface and internal structure of POE film are still subject to many challenges in outdoor environments and harsh working conditions. First, long-term exposure to strong sunlight will accelerate the aging process of the material, causing the molecular chain to break and then cracks to occur. Secondly, oxidation cannot be ignored. The oxygen in the air reacts with the unsaturated bonds in the material, destroying its chemical structure, causing the material performance to deteriorate and cracks to occur. In addition, continuous external loads will also cause high stress in local areas of the material, thereby promoting the formation and expansion of cracks. The above factors work together, and photovoltaic modules will be affected by the above factors during long-term service, and POE film will inevitably crack or be damaged. The molecular structure design can give it self-healing ability, which means that when the material has tiny cracks, under external stimulation, the special mechanism inside the cross-linked network can be automatically triggered to repair the damage and restore the integrity and performance of the material. Good adhesion enables the material to better resist peeling and falling off when subjected to external forces, and maintain the stability of the structure. This can not only significantly improve the durability and reliability of the material, reduce the replacement and repair of photovoltaic modules due to cracks in the encapsulation film, but also effectively extend its service life.

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

[0005] CN202411418686.6 discloses a cement mortar for road repair and a preparation method thereof. The invention comprises the following steps: firstly preparing a multi-hydrogen bond chain extender, and then preparing an aqueous polyurethane emulsion and an aqueous epoxy emulsion; mixing the aqueous polyurethane emulsion and the aqueous epoxy emulsion, and then adding nano titanium dioxide and a silane coupling agent to obtain a polymer reinforced emulsion; and mixing and stirring silicate cement, fast-hardening sulphoaluminate cement, fly ash, a polymer reinforced emulsion, a curing agent, water, a defoaming agent, and a water reducing agent to obtain a cement mortar for road repair, i.e., a material having self-repairing properties by adding nano-particle materials.

[0006] CN202411180760.5 discloses a preparation method and application of intelligent magnetically targeted hyperbranched polyurethane self-healing microcapsules, which are composed of photosensitive microcapsules capable of magnetically targeted distribution and epoxy resin.

[0007] CN202222853645.2 discloses an adhesive film with self-repairing function, which includes a polymer base film, an adhesive layer coated under the base film, and another self-repairing functional layer coated on the base film.

[0008] CN201810329859.5 discloses a polyolefin encapsulation film with self-healing function, which includes the following components in parts by mass: 80-100 parts of encapsulation film substrate POE, 8-15 parts of supramolecular self-healing functional compounds, 0.5-2.0 parts of cross-linking agents, 0.2-2.0 parts of antioxidants, 0.02-1.0 parts of ultraviolet light stabilizers, and 0.5-2.0 parts of tackifiers, wherein the supramolecular self-healing functional compounds are self-polymerized from polysiloxane or polysilsesquioxane monomers containing olefin amide, and have a cross-linked network macromolecular structure.

[0009] However, the above methods have some obvious defects: First, the content of external repair agent is limited. As the number of repairs increases, the repair effect will gradually weaken until the repair agent is exhausted; second, the dispersibility and compatibility of the repair agent are difficult to guarantee, and it is easy to have agglomeration, stratification and other phenomena. If the uniformity of the material is not good, it will affect its normal use; third, external repair materials often require specific trigger conditions to heal, which increases the difficulty and cost of repair and reduces the efficiency of repair.

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

[0011] In view of this, this invention is proposed. Summary of the invention

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

[0013] The second object of the present invention is to provide a self-healing encapsulation film, by introducing reversible borate ester bonds into the film material, constructing a dynamically rearrangeable three-dimensional cross-linked network structure, and giving the material the characteristic of intrinsic repair. The raw materials for preparing the encapsulation film include the following components by mass: 90-110 parts of polyolefin copolymer POE, 0.5-5 parts of self-healing functional monomer, 0.2-3 parts of cross-linking agent, 0.2-3 parts of antioxidant, 0.2-3 parts of light stabilizer and 0.2-3 parts of tackifier.

[0014] The third object of the present invention is to provide a method for preparing a packaging film, which specifically includes the following steps: mixing a polyolefin copolymer POE, a self-healing functional monomer, a cross-linking agent, an antioxidant, a light stabilizer and a tackifier, and obtaining a mixture after uniform stirring; extruding and casting the mixture to obtain the packaging film.

[0015] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0017] Among them, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione can be purchased commercially or prepared by itself. The preparation method is as follows: under stirring conditions, 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborolane (CAS No. 342002-80-6) and N-phenylmaleimide (CAS No. 941-69-5) are mixed in a certain molar ratio and heated for reaction. After the reaction is completed, the product is placed in an environment of 120° C. and dried for 3 hours to remove free dioxaborolane, thereby obtaining 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione. The molar ratio of the 2-isopropoxy-4,4,5,5-methyl-1,3,2-dioxaborane to N-phenylmaleimide is preferably 2:1, the reaction temperature is preferably 80° C., and the reaction time is preferably 3 hours.

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

[0019] Furthermore, the molar ratio of 1-[(2-phenyl-1,3,2-dioxaborolan-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolan] 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] Furthermore, the weak alkaline solution is a sodium bicarbonate solution, a potassium bicarbonate solution, or an ammonium carbonate solution, preferably a sodium bicarbonate solution.

[0021] The present invention also provides a method for preparing a self-healing functional monomer for a polyolefin adhesive film, comprising: under stirring conditions, adding 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] in a molar ratio of (0.9-1.2):1 to an alkaline solution, heating to carry out an exchange reaction, and obtaining a self-healing functional monomer.

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

[0023] Furthermore, the molar concentration of the weak alkaline solution is (0.3-0.6) mol / L, for example, it can be 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] Furthermore, the molar concentration of the sodium bicarbonate solution is (0.3-0.6) mol / L, for example, it can be 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] Furthermore, the temperature of the exchange reaction is (60-90)°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc.

[0026] Furthermore, the exchange reaction time is (2-5) h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc.

[0027] Furthermore, after the exchange reaction is completed, acid washing and drying are performed to remove salt impurities to obtain a self-healing functional monomer.

[0028] Furthermore, during the pickling process, a dilute hydrochloric acid solution is added, and the molar concentration of the dilute hydrochloric acid solution is (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] Furthermore, the temperature of the drying process is 100-140°C, for example, 110°C, 120°C, 125°C, 130°C, etc.

[0030] Furthermore, the drying process takes 1-5 hours, for example, 2 hours, 3 hours, 4 hours, etc.

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

[0032] Furthermore, in the raw materials for preparing the encapsulation film, the content of the polyolefin copolymer is 90 to 110 parts, for example, 90 parts, 95 parts, 100 parts, 105 parts, 110 parts, etc., preferably 100 parts.

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

[0034] Furthermore, in the raw materials for preparing the encapsulating film, the content of the crosslinking agent is 0.2 to 3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., preferably 0.6 to 1.8 parts.

[0035] Furthermore, in the raw materials for preparing the encapsulating film, the content of the antioxidant is 0.2 to 3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., preferably 0.2 to 1.5 parts.

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

[0037] Furthermore, in the raw materials for preparing the encapsulating film, the content of the tackifier is 0.2 to 3 parts, for example, it can be 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, etc., preferably 0.6 to 2 parts.

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

[0039] Further, the cross-linking agent is any one of dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl carbonate, diisopropyl peroxide, tert-butyl peroxy-isopropyl carbonate, ethyl-3,3-di(tert-butylperoxy)butyrate, tert-amyl perbenzoate, and tert-butyl peroxycarbonate-2-ethylhexyl ester, or a combination of at least two thereof.

[0040] Further, the antioxidant is any one of tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis(4-hydroxy-3,5-butylphenylpropionate), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol, distearyl pentaerythritol diphosphite, N,N'-1,6-hexanediyl di(3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionyl), 2,6-di-tert-butyl-p-methylphenol, and pentaerythritol bisphosphite di(octadecyl) ester, or a combination of at least two thereof.

[0041] Further, the light stabilizer is any one of (2,2,6,6-tetramethyl-4-piperidinyl) 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, and 2-(2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, or a combination of at least two thereof.

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

[0043] Furthermore, the polyolefin copolymer, the self-healing functional monomer, the cross-linking agent, the antioxidant, the light stabilizer and the tackifier are mixed and stirred evenly to obtain a mixture; the mixture is extruded and cast to obtain the encapsulation film.

[0044] In a third aspect, the present invention provides a method for preparing an encapsulating 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 a tackifier to obtain a mixture after uniform stirring; and extruding and casting the mixture to obtain the encapsulating film.

[0045] Furthermore, the components are calculated by weight as follows: 90 to 110 parts of polyolefin copolymer, 0.5 to 5 parts of self-healing functional monomer, 0.2 to 3 parts of cross-linking agent, 0.2 to 3 parts of antioxidant, 0.2 to 3 parts of light stabilizer and 0.2 to 3 parts of tackifier.

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

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

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

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

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

[0051] The present invention provides a method for preparing a self-healing POE encapsulation film, which can be applied to the field of solar cell encapsulation. Self-healing functional monomers are introduced into the polyolefin copolymer POE molecular chain by means of reactive extrusion graft copolymerization. The borate bond has dynamic reversibility under certain conditions, so it can improve the specific properties of the film material. On the one hand, the borate bond can quickly switch between breaking and forming, and this dynamic behavior enables the material to more easily adjust its molecular structure and spatial configuration when subjected to external forces, thereby showing higher flexibility. This gives the POE encapsulation film in the lamination process stronger fluidity, thereby forming a closer bond with the glass to achieve a higher adhesion strength. On the other hand, thanks to the unique properties of the borate bond, the damaged part of the material can achieve self-healing through the structural rearrangement of the three-dimensional cross-linked network. During the dynamic exchange process, the cross-linking density and structural integrity of the network remain unchanged, which gives the POE film as an encapsulation material excellent intrinsic self-healing ability and reprocessing performance.

[0052] Compared with the prior art, the self-healing POE encapsulation film proposed in the present invention has the following advantages:

[0053] (1) Introducing self-healing functional monomers with borate bonds and dioxyborane structures into the network structure of the adhesive film not only improves the chemical stability of the adhesive film material, but also the stronger fluidity allows the adhesive film to form a tighter bond with the glass during the lamination process, greatly improving the adhesion strength and better resisting peeling and falling off under extreme conditions.

[0054] (2) Reversible borate bonds are introduced into the molecular chain to construct a three-dimensional cross-linked network with dynamic configuration. After the film is damaged, the movement of the molecular chain causes the dissociated borate bonds to collide with each other and reorganize, thereby forming a complete network structure again, which is manifested as the healing of damage on a macro scale. This process can be carried out at room temperature. The POE encapsulation film can achieve multiple, efficient, and special condition-free healing through intrinsic self-repairing means, which has practical value for reducing the difficulty and cost of repairing encapsulated components and extending their service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The chemical structure and infrared spectrum of the self-healing functional monomer;

[0056] Figure 2 Infrared spectra of the packaging films provided in Example 1 and Comparative Example 1;

[0057] Figure 3 The electron microscope images of the self-healing of scratches on the packaging film provided in Example 2 are obtained, and the self-healing test was performed using scratches of different widths. DETAILED DESCRIPTION

[0058] In order to make it easier to understand the structure of the present invention and the functional features and advantages that can be achieved, the technical solution will be described in detail and completely in combination with the preferred embodiments of the present invention.

[0059] Example 1

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

[0061] This embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] are added to a 0.3 mol / L sodium bicarbonate solution at a molar ratio of 0.9:1, and the exchange reaction is carried out at 60°C for 5 hours. After the reaction is completed, the above mixture is added to a 0.5 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0062] (2) Preparation of polyolefin encapsulation film

[0063] This embodiment provides a method for preparing a self-healing polyolefin encapsulation film. The raw materials for preparing the encapsulation film include the following components in parts by mass:

[0064] Polyolefin copolymer Ethylene-propylene copolymer 100 copies Crosslinking agent Benzoyl peroxide 0.6 parts Antioxidants Tris(2,4-di-tert-butylphenyl)phosphite 1.5 servings Light Stabilizer (2,2,6,6-Tetramethyl-4-piperidinyl) sebacate 0.2 parts Tackifier 3-Aminopropyltrimethoxysilane 2 servings Self-healing functional monomer Self-healing functional monomer provided in Example 1 1.5 servings

[0065] The encapsulation film is prepared according to the following steps: polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier are mixed, placed in a mixing kettle and stirred at a speed of 250r / min for 50min to obtain a mixture; the mixture is extruded and granulated at 100°C and a screw speed of 50r / min. The granules are cast and rolled at 120°C and a winding speed of 5m / min to obtain the encapsulation film.

[0066] Example 2

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

[0068] This embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] are added to a 0.4 mol / L sodium bicarbonate solution at a molar ratio of 1:1, and the exchange reaction is carried out at 70°C for 4 hours. After the reaction is completed, the above mixture is added to a 0.6 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0069] (2) Preparation of polyolefin encapsulation film

[0070]

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

[0072] Example 3

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

[0074] This embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] are added to a 0.45 mol / L sodium bicarbonate solution at a molar ratio of 1.05:1, and the exchange reaction is carried out at 75°C for 3.5 hours. After the reaction is completed, the above mixture is added to a 0.7 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0075] (2) Preparation of polyolefin encapsulation film

[0076]

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

[0078] Example 4

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

[0080] This embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] 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°C for 3 hours. After the reaction is completed, the above mixture is added to a 0.8 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0081] (2) Preparation of polyolefin encapsulation film

[0082]

[0083]

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

[0085] Example 5

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

[0087] The present embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] are added to a 0.55 mol / L sodium bicarbonate solution at a molar ratio of 1.15:1, and the exchange reaction is carried out at 85°C for 2.5 hours. After the reaction is completed, the above mixture is added to a 0.9 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0088] (2) Preparation of polyolefin encapsulation film

[0089]

[0090]

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

[0092] Example 6

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

[0094] This embodiment provides a self-healing functional monomer, and the preparation method of the self-healing functional monomer is as follows: under stirring conditions, 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] are added to a 0.6 mol / L sodium bicarbonate solution at a molar ratio of 1.2:1, and the exchange reaction is carried out at 90°C for 2 hours. After the reaction is completed, the above mixture is added to a 1.0 mol / L dilute hydrochloric acid solution for pickling, and then placed in a 120°C environment for drying for 3 hours to remove the solvent, and finally the salt impurities are filtered out to obtain a self-healing functional monomer.

[0095] (2) Preparation of polyolefin encapsulation film

[0096]

[0097] The encapsulation film is prepared according to the following steps: polyolefin copolymer POE, self-healing functional monomer, crosslinking agent, antioxidant, light stabilizer and tackifier are mixed, placed in a mixing kettle and stirred at a speed of 500r / min for 25min to obtain a mixture; the mixture is extruded and granulated at 130°C and a screw speed of 80r / min. The granules are cast and rolled at 130°C and a winding speed of 10m / min to obtain the encapsulation film.

[0098] Comparative Example 1

[0099] The preparation method of Example 1 was repeated according to the specified proportions of each component, but no self-healing functional monomer was added.

[0100] Comparative Example 2

[0101] The preparation method of Example 2 was repeated according to the specified proportions of each component, but no self-healing functional monomer was added.

[0102] Comparative Example 3

[0103] The preparation method of Example 3 was repeated according to the specified proportions of each component, but no self-healing functional monomer was added.

[0104] Comparative Example 4

[0105] The preparation method of Example 4 was repeated according to the specified proportions of each component, but no self-healing functional monomer was added.

[0106] Test 1: Infrared test.

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

[0108] Test samples: the self-healing functional monomer and packaging film provided in Example 1, and the packaging film provided in Comparative Example 1.

[0109] Test method: The self-healing functional monomer does not need to be processed and can be directly tested. Laminate a single layer of packaging film: vacuum time 390s, lamination time 530s, lamination temperature 145℃. Test the laminated packaging film.

[0110] Test 2: Adhesion test.

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

[0112] Test samples: the packaging films provided in Examples 1 to 6 and the packaging films provided in Comparative Examples 1 to 4.

[0113] Test method: Lamination is performed according to the structure of glass / high temperature cloth / encapsulation film / encapsulation film / back sheet: vacuuming time 390s, lamination time 530s, lamination temperature 145°C. Adhesion test is performed on the laminated samples in accordance with 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 samples: the packaging films provided in Examples 1 to 6 and the packaging films provided in Comparative Examples 1 to 4.

[0117] Test method: Lamination of double-layer packaging film: vacuum time 390s, lamination time 530s, lamination temperature 145℃. Use a scalpel to make scratches on the surface of the packaging film, place it on the stage, and observe the changes in the scratch width at room temperature, that is, the self-healing behavior. The scratch width at the beginning of observation is recorded as the initial scratch width. When the scratch width no longer changes, the scratch width at this time is recorded as the scratch width after healing. The self-healing efficiency of the packaging film is calculated as follows:

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

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

[0120] The encapsulation films provided in Example 1 and Comparative Example 1 were characterized by infrared spectra. Figure 2 Compared with Comparative Example 1, the spectrum of Example 1 at 1152 cm -1 There is an obvious borate ester bond (BOC) characteristic peak at 1470 nm, which indicates that the dioxaborane structure in the self-healing functional monomer is introduced into the cross-linked network of the polyolefin copolymer by means of graft copolymerization.

[0121] The encapsulation films provided in Examples 1 to 6 and Comparative Examples 1 to 4 were tested for adhesion and self-healing performance, 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 films provided in Examples 1 to 6 have a higher adhesion to the glass (>120 N / cm), and the self-healing efficiency of the scratch repair test at room temperature is significantly higher than that of the films provided in Comparative Examples 1 to 4, and the self-healing efficiency is higher than 95%. Figure 3 As shown, the encapsulation film provided in Example 2 was subjected to self-repair tests of different scratch widths, and its self-repair efficiency was as high as 100%. The above analysis shows that the introduction of borate bonds can effectively improve the adhesion and self-healing properties of polyolefin copolymers. The POE encapsulation film provided by the present invention can meet the needs of improving the utilization rate of photovoltaic modules.

[0125] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. All equivalent changes and modifications made according to the content of the present invention are included in the patent scope of the present invention.

Claims

1. A self-healing functional monomer for a polyolefin film, wherein the raw materials for preparing the self-healing functional monomer include: 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane], the two raw materials are reacted in a weak alkaline solution to obtain a self-healing functional monomer.

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

1.

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

4. The method for preparing a self-healing functional monomer according to any one of claims 1 to 3, comprising, under stirring conditions, adding 1-[(2-phenyl-1,3,2-dioxaborolane-4-yl)methyl]-1H-pyrrole-2,5-dione and 2,2'-(1,4-phenylene)-bis[4-methyl-1,3,2-dioxaborolane] in a molar ratio of (0.9 to 1.2):1 to an alkaline solution, heating to carry out an exchange reaction, and obtaining 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 temperature of the exchange reaction is (60-90)°C.

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

8. The method for preparing the self-healing functional monomer according to claim 4, characterized in that: After the exchange reaction is completed, acid washing and drying are performed to remove salt impurities to obtain a self-healing functional monomer.

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

10. A packaging film, wherein the raw materials for preparing the packaging film include the following components in parts by mass: 90 to 110 parts of a polyolefin copolymer, 0.5 to 5 parts of a self-healing functional monomer as described in any one of claims 1 to 3 or a self-healing functional monomer prepared by the preparation method of any one of claims 4 to 9, 0.2 to 3 parts of a cross-linking agent, 0.2 to 3 parts of an antioxidant, 0.2 to 3 parts of a light stabilizer and 0.2 to 3 parts of a tackifier.

11. The packaging adhesive film according to claim 10, characterized in that: The polyolefin copolymer is any one of ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-hexene copolymer, ethylene-heptene copolymer, and ethylene-nonene copolymer, or a combination of at least two thereof.

12. The packaging film according to claim 10, characterized in that: The crosslinking agent is any one of dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl carbonate, diisopropyl peroxide, tert-butyl peroxy-isopropyl carbonate, ethyl-3,3-di(tert-butylperoxy)butyrate, tert-amyl perbenzoate, and tert-butyl peroxycarbonate-2-ethylhexyl ester, or a combination of at least two thereof.

13. The packaging adhesive film according to claim 10, characterized in that: The antioxidant is any one of tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis(4-hydroxy-3,5-butylphenylpropionate), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol, distearyl pentaerythritol diphosphite, N,N'-1,6-hexanediyl di(3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionyl), 2,6-di-tert-butyl-p-methylphenol, and pentaerythritol bisphosphite di(octadecyl) ester, or a combination of at least two thereof.

14. The packaging film according to claim 10, characterized in that: The light stabilizer is any one of (2,2,6,6-tetramethyl-4-piperidinyl) 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, and 2-(2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, or a combination of at least two thereof.

15. The packaging adhesive film according to claim 10, characterized in that: The adhesion promoter is any one of 3-aminopropyltrimethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, methacryloxypropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and 4-amino-3,3-dimethylbutyltrimethoxysilane, or a combination of at least two thereof.

16. The packaging adhesive film according to claim 10, characterized in that: The polyolefin copolymer, the self-healing functional monomer, the cross-linking agent, the antioxidant, the light stabilizer and the tackifier are mixed and uniformly stirred to obtain a mixture; the mixture is extruded and cast to obtain the encapsulation film.

17. A method for preparing a packaging film according to any one of claims 10 to 16, comprising the following steps: The polyolefin copolymer, the self-healing functional monomer, the cross-linking agent, the antioxidant, the light stabilizer and the tackifier are mixed and uniformly stirred to obtain a mixture; the mixture is extruded and cast to obtain the encapsulation film.

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

19. An application of a self-healing functional monomer in the self-repair of a polyolefin film, wherein the self-healing functional monomer is the self-healing functional monomer described in one of claims 1 to 3 or a self-healing functional monomer prepared by the preparation method of one of claims 4 to 9, wherein the self-healing functional monomer is introduced into a polyolefin copolymer molecular chain.

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

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