Ethylene / alpha-olefin copolymer and preparation method thereof, and packaging film using the same

Abstract

The present invention belongs to the technical field of polymer materials, and provides an ethylene / olefin copolymer and a preparation method thereof, and an encapsulation film using the same; the surface roughness of the ethylene / olefin copolymer is 80-140. Through the design of the surface roughness, it has a special microstructure, a narrow molecular weight distribution and a low soluble content. The ethylene / olefin copolymer is used in the encapsulation film, and its absorption time for the auxiliary agent is shortened, and the vulcanization reaction speed and crosslinking degree of the encapsulation film are improved. The encapsulation film prepared by the encapsulation film realizes the performance optimization of polymer particles in photovoltaic application scenarios, and meets the application requirements in solar cell modules.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials and specifically relates to an ethylene / Olefin copolymer and its preparation method, and packaging film using the same. Background Art

[0002] Photovoltaic encapsulation film is one of the important materials in the photovoltaic industry. It plays the role of bonding solar cells to glass and backplanes. It also has multiple functions of mechanical buffering, encapsulation protection, and anti-ultraviolet protection for photovoltaic modules. Photovoltaic encapsulation film is one of the key materials that affect the service life and power generation of photovoltaic modules. The technical research and development and upgrading of photovoltaic encapsulation film have a driving significance for the development of the photovoltaic industry.

[0003] At present, the market mainly uses polyolefin elastomer (POE) packaging film, which has obvious advantages in terms of light, heat and oxygen aging, resistance to potential induced degradation (PID), etc. However, the polarity of POE film is low, the adhesion to glass or backplane is not strong, and it is easy to cause string deviation during lamination. At the same time, the compatibility of POE resin with polar additives is poor, and it is easy to precipitate during subsequent processing and use. At the same time, for the consideration of cost reduction, the mainstream packaging of photovoltaic cells is transitioning from pure POE to composite film (EPE), that is, ethylene-vinyl acetate copolymer (EVA) and POE are co-extruded, with POE as the middle layer and EVA as the outer layer on both sides, and the film product is obtained by compounding. In the actual use of downstream film manufacturers, the degree of cross-linking of the film is still the key to ensuring the insulation packaging performance of the material. However, due to the presence of a non-polar main chain of POE and the lack of functional groups to promote the rapid cross-linking vulcanization reaction, POE inherently has a gap with the cross-linking vulcanization performance of EVA itself. Therefore, when the film factory prepares EPE film, the cross-linking degree of the final product is often low, and it is also difficult to eliminate the delamination and bubbling of the product. The root cause is that POE itself cross-links slowly, so along with the migration of the P-layer additives in the EPE to the E-layer due to the polarity of the material, the E-layer in the EPE cross-links faster, resulting in the gas in the P-layer being locked in the product before it is completely removed, and at the same time, the product is not fully cross-linked and has a low cross-linking degree.

[0004] In order to improve the overall cross-linking degree of EPE film, many methods and means have been developed from formula to process. CN106281122A discloses a composite cross-linking agent for POE encapsulation film. This technical means starts from the cross-linking agent formula, utilizes the compounding and synergistic effect of high-activity peroxide and low-activity peroxide, and improves the overall cross-linking degree of POE. CN117801691A and CN117467367A introduce polar polyurethane structure and silane grafting structure into the P layer and POE in EPE, respectively, so as to reduce the migration of the auxiliary agent of the POE layer, so as to improve the final cross-linking degree of the product. CN116004126A improves the cross-linking characteristics by changing the layer structure of the encapsulation film, and comprehensively improves the encapsulation effect of POE applied in the assembly. However, there are few reports based on the molecular structure of POE itself to optimize and improve its cross-linking and vulcanization performance. In addition, improving the auxiliary agent absorption rate of the raw material particles is conducive to shortening the overall processing time, thereby achieving a greater degree of cost reduction and efficiency improvement, and there is still a lack of relevant research in the prior art.

[0005] Therefore, how to reduce the additive absorption time of the copolymer and how to make the photovoltaic encapsulation film prepared by using the copolymer have a shorter processing aging time and a faster crosslinking vulcanization reaction speed have become problems that need to be solved urgently. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide an ethylene / Olefin copolymer and preparation method thereof, packaging film using the same, the ethylene / Olefin copolymers have a high surface roughness, which makes the particles have a short additive absorption time. The photovoltaic encapsulation film prepared using them has a short processing aging time and a faster cross-linking vulcanization reaction rate, and can be effectively used as an insulating packaging material for photovoltaic cell modules.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides an ethylene / Olefin copolymer, the ethylene / The surface roughness of the olefin copolymer is 80-140; the calculation formula of the surface roughness is shown in Formula I:

[0009] Formula I.

[0010] In Formula I, Indicates the surface roughness, Indicates ethylene / Density of olefin copolymers, d avg Indicates ethylene / The average particle size of the olefin copolymer particles, ABET It means ethylene obtained by BET test method / Specific surface area of ​​olefin copolymer particles.

[0011] The ethylene / The surface roughness of the olefin copolymer is 80-140. The high surface roughness makes it have excellent auxiliary agent absorption speed. When preparing the film (such as photovoltaic film), it is mixed with auxiliary agents such as crosslinking agents, heated and stirred to complete the auxiliary agent absorption (also known as aging), and then extruded and cast to obtain the corresponding film. The obtained film and battery cells, encapsulation glass, photovoltaic backplane, etc. are cross-linked and compounded under a certain temperature and pressure to obtain the final product photovoltaic module. The rough-surfaced ethylene / Olefin copolymers make it easier for additives to be absorbed by the particle surface, thereby shortening the additive absorption time, increasing the cross-linking rate and degree, and improving the processing efficiency of the film factory.

[0012] It should be noted that the ethylene / The surface roughness of olefin copolymers indicates the The surface roughness of the olefin copolymer (pellets / particles) is calculated using the particle surface roughness calculation formula shown in Formula I.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] In the present invention, the ethylene / The surface roughness of the olefin copolymer (its pellets / particles) is 80-140, for example, 82, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135 or 138, etc., preferably 100-135.

[0015] In the present invention, the ethylene / The surface roughness of the olefin copolymer is 80-140. On the one hand, its larger roughness is conducive to the absorption of the additive, shortening the absorption time of the additive, and improving the vulcanization speed and the production efficiency of the film; on the other hand, the ethylene / The olefin copolymer still maintains a relatively high molecular weight and excellent cross-linking and vulcanization performance, so that the encapsulation film prepared by using it has a high degree of cross-linking. If the surface roughness of the copolymer is less than 80, the absorption rate of the additive is reduced and the vulcanization time of the film is long; if the surface roughness of the copolymer is greater than 140, the molecular weight is reduced, which in turn affects the cross-linking degree of the film.

[0016] Preferably, the ethylene / The weight average molecular weight of the olefin copolymer is 40,000-130,000 g / mol, for example, 50,000 g / mol, 60,000 g / mol, 80,000 g / mol, 100,000 g / mol or 120,000 g / mol.

[0017] And / or, preferably, the ethylene / The molecular weight distribution of the olefin copolymer is 2.3-2.6, for example, it may be 2.35, 2.4, 2.45, 2.5 or 2.55.

[0018] In the present invention, the weight average molecular weight (M w ) and number average molecular weight (M n ) is the converted molecular weight of polystyrene (PS) analyzed by gel permeation chromatography (GPC)-infrared (IR), and the molecular weight distribution (PDI) is M w / M n .

[0019] And / or, preferably, the ethylene / The mass content of soluble matter in the elution peak of the olefin copolymer measured by temperature gradient cross chromatography (TGIC) is ≤3.0%, for example, it can be 2.9%, 2.8%, 2.5%, 2.2%, 2%, 1.8%, 1.5%, 1.2%, 1% or 0.5%.

[0020] In the present invention, the soluble content is analyzed by a TGIC instrument of polymer char, and the analysis method is as follows: the sample is dissolved in trichlorobenzene at 165°C and passed through a TGIC chromatographic column, and the temperature is programmed to be lowered to 40°C (the cooling rate is 20°C / min). Part of the polyolefin structure is attached to the chromatographic column due to adsorption and crystallization with the graphite column, and the mobile phase is used for flushing at a flow rate of 0.5 mL / min, wherein the mobile phase composition is 2 g of BHT (2,6-di-tert-butyl-p-cresol) dissolved in 4 L of trichlorobenzene, and the soluble part is flushed to the detector for detection, and the temperature is raised to 165°C at a rate of 2°C / min. The molecules attached to the column are washed out in sequence according to their crystallization ability differences and the number of short side chains.

[0021] Preferably, the Olefins are selected from C3-C20 Any one or a combination of at least two of the olefins; wherein C3-C20 Olefins are specifically C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20 Olefins.

[0022] Preferably, the The olefins include any one of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene, or a combination of at least two thereof.

[0023] In the present invention, ethylene / Olefin copolymers The olefin content can be appropriately selected within the range satisfying the physical conditions without limitation. Olefins in ethylene / The molar content in the olefin copolymer is 0.01-40%, for example, it can be 0.5%, 1%, 2%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35% or 38%, etc.

[0024] Preferably, the ethylene / Olefin copolymers based on The mass percentage of the structural unit of olefin is 1-50%, for example, it can be 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, etc.

[0025] In a second aspect, the present invention provides an ethylene / A method for preparing an olefin copolymer, the preparation method comprising:

[0026] Ethylene, The olefin is polymerized in the presence of a catalyst to obtain a polymer melt; the polymer melt is melt-extruded, injected into a coagulation bath of a ternary solvent system, and then pelletized to obtain the ethylene / Olefin copolymer; the ternary solvent system comprises a combination of water, a poor solvent and a good solvent.

[0027] In the preparation method of the present invention, a ternary mixed system of water, a poor solvent and a good solvent is used as a coagulation bath solvent during the extrusion granulation process of the polymer melt, thereby micro-etching the polymer surface during the extrusion process of the polymer melt to make the ethylene / The surface roughness of the olefin copolymer pellets is >80.

[0028] In the present invention, the poor solvent refers to ethylene / Poor solvent for olefin copolymers, ethylene / Olefin copolymer solutes have weak solubility, and the preferred poor solvent is the interaction parameter with the copolymer solute. ≥0.5 of solvent.

[0029] In the present invention, the good solvent refers to ethylene / Good solvent for olefin copolymers, ethylene / The olefin copolymer solute has a strong solubility in the solvent, preferably a good solvent, which is the interaction parameter with the copolymer solute. <0.5 of solvent.

[0030] Furthermore, using ethylene / The coagulation bath obtained by combining the good solvent of olefin copolymer with water and poor solvent enables the copolymer to achieve polymer molecular weight classification during the melt extrusion process. Some polymer fractions with extremely small molecular weight but high insertion rate are not conducive to the subsequent vulcanization and crosslinking of the film. This is because on the one hand, their molecular weight is small and their contribution to the crosslinking reaction is weak; on the other hand, due to the high insertion rate, a large amount of crosslinking agent is consumed. These small fractions are equivalent to "gel points", so that the crosslinking agent does not work on the polymer body. Therefore, this part of the polymer fraction is not conducive to the crosslinking vulcanization reaction. Through the coagulation bath treatment of the mixed solvent, the final polymer molecular weight distribution PDI is narrowed, the soluble content is reduced, and the small molecular fraction is eliminated, thereby improving the overall crosslinking and vulcanization performance of the final film.

[0031] Preferably, the mass content of water in the ternary solvent system is 50-82%, for example, it can be 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78% or 80%, etc.

[0032] Preferably, the mass content of the poor solvent in the ternary solvent system is 8-32%, for example, it can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28% or 30%.

[0033] Preferably, the poor solvent is a C2-C20 alcohol solvent, for example, it may be a C3, C4, C6, C8, C10, C12, C15 or C18 alcohol solvent.

[0034] Preferably, the poor solvent includes any one of ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, n-decanol, dodecanol, tetradecanol, and hexadecanol, or a combination of at least two thereof.

[0035] Preferably, the mass content of the good solvent in the ternary solvent system is 4-20%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16% or 18%, etc.

[0036] Preferably, the good solvent includes an aliphatic solvent and / or an aromatic solvent.

[0037] Preferably, the aliphatic solvent used as the good solvent includes any one or a combination of at least two of C4-C15 (for example, C5, C6, C7, C8, C10, C12 or C14, etc.) straight-chain or branched alkanes, C5-C10 (for example, C6, C7, C8 or C9) cycloalkanes, and further preferably any one or a combination of at least two of n-butane, isobutane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, and isomeric alkane solvents.

[0038] Preferably, the aromatic solvent used as the good solvent includes any one or a combination of at least two of C6-C30 (for example, C8, C10, C12, C16, C20, C24 or C28, etc.) aromatic hydrocarbons, halogen-substituted C6-C30 (for example, C8, C10, C12, C16, C20, C24 or C28, etc.) aromatic hydrocarbons, and further preferably any one or a combination of at least two of benzene, toluene, xylene, halogenated benzene, halogenated toluene and halogenated xylene.

[0039] In the present invention, the halogenated benzene, halogenated toluene and halogenated xylene each independently include monohalogenated compounds and / or polyhalogenated compounds thereof.

[0040] Preferably, the polymerization method is a solution polymerization reaction, that is, the polymerization reaction is carried out in the presence of a solvent (reaction solvent).

[0041] The ethylene / The olefin copolymer preparation method preferably adopts the solution polymerization method, in which a solvent and After olefins are mixed in a certain proportion, they are injected into the reactor, ethylene gas is introduced at high temperature, and then the main catalyst and the co-catalyst are added into the reactor for stirring reaction. The polymer process parameters are controlled by one or more steps of feeding to obtain a reactant solution. The reactant solution is then devolatilized to obtain the desired polymer melt, which is then extruded, precipitated, stretched, and pelletized in a coagulation bath to obtain a particle product.

[0042] Preferably, the method for preparing the polymer melt comprises: reacting a reaction solvent, Olefins, main catalysts and co-catalysts are mixed, ethylene is introduced to carry out polymerization reaction, and volatilization is carried out to obtain the polymer melt.

[0043] Preferably, the reaction solvent is The mass ratio of olefins is (0.5-5):1, for example, it can be 0.6:1, 0.8:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or 4.5:1, etc.

[0044] Preferably, the reaction solvent comprises an aliphatic solvent and / or an aromatic solvent.

[0045] Preferably, the aliphatic solvent used as the reaction solvent includes any one or a combination of at least two of n-butane, isobutane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane and their alkylated compounds, and isoparaffin solvents.

[0046] Preferably, the aromatic solvent used as the reaction solvent includes any one of benzene, toluene, xylene, halogenated benzene, halogenated toluene, and halogenated xylene, or a combination of at least two of them.

[0047] Preferably, the main catalyst comprises a metallocene catalyst and / or a post-metallocene catalyst.

[0048] Preferably, the main catalyst includes any one of dimethylsilyl (N-tert-butylamino) -(tetramethylcyclopentadienyl) titanium dichloride, bis(methylcyclopentadienyl) zirconium dichloride, bis(1,3-dimethylcyclopentadienyl) zirconium dichloride, cyclopentadienyl-(1,2-dimethoxyethane) zirconium trichloride, dimethylsilyl bis(2-methyl-4-phenylindenyl) zirconium dichloride, and dimethylsilyl tert-butylamino tetramethylcyclopentadienyl titanium dichloride, or a combination of at least two thereof.

[0049] Preferably, in the reaction solvent, In the mixed solution of olefin, main catalyst and co-catalyst, the concentration of the main catalyst is 1-20 μmol / L, for example, 2 μmol / L, 5 μmol / L, 8 μmol / L, 10 μmol / L, 12 μmol / L, 15 μmol / L or 18 μmol / L.

[0050] Preferably, the co-catalyst includes any one of alkyl aluminum, organic boron compound, alkyl aluminoxane or a combination of at least two thereof.

[0051] Preferably, the co-catalyst includes any one or a combination of at least two of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum or tris(pentafluorophenyl)boron compounds.

[0052] Preferably, the total molar amount of aluminum element and boron element in the co-catalyst is recorded as n1, the molar amount of the metal element in the main catalyst is recorded as n2, and n1:n2 is (1-1000):1, for example, it can be 2:1, 5:1, 8:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 400:1, 450:1, 500:1, 550:1, 600:1, 650:1, 700:1, 750:1, 800:1, 850:1, 900:1 or 950:1, etc.

[0053] Preferably, the polymerization reaction temperature is 100-200°C, for example, 110°C, 130°C, 150°C, 170°C or 190°C.

[0054] Preferably, the pressure is 10-100 bar, for example, 20 bar, 30 bar, 40 bar, 50 bar, 60 bar, 70 bar, 80 bar or 90 bar, etc.

[0055] Preferably, the devolatilization temperature is 180-300°C, for example, 190°C, 200°C, 210°C, 230°C, 250°C, 270°C or 290°C.

[0056] In a third aspect, the present invention provides a packaging film, wherein the raw materials for preparing the packaging film include the ethylene / Olefin copolymers.

[0057] Preferably, the preparation raw materials further include a cross-linking agent and a co-cross-linking agent.

[0058] Preferably, the cross-linking agent comprises an organic peroxide, and further preferably isopropyl tert-butyl peroxycarbonate, 2,5-dimethyl-2,5-(bis-tert-butylperoxy)hexane, 2-ethylhexyl tert-butylperoxycarbonate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)-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-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxycarbonate, tert-butyl peroxy-3,3,5-trimethylhexanoate or a combination of at least two thereof.

[0059] Preferably, the auxiliary crosslinking agent includes a multifunctional olefin-containing compound, and more preferably 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, ditrihydroxymethyl Any one or a combination of at least two of propane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and triallyl isocyanurate.

[0060] Preferably, the ethylene / The mass of the olefin copolymer is 100 parts, and the mass of the crosslinking agent is 0.1-5 parts, for example, it can be 0.2 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts, and more preferably 0.5-2 parts.

[0061] Preferably, the ethylene / The mass of the olefin copolymer is 100 parts, and the mass of the co-crosslinking agent is 0.1-5 parts, for example, it can be 0.2 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts, etc., and more preferably 0.1-2 parts.

[0062] Preferably, the preparation further comprises a coupling agent and / or an antioxidant.

[0063] Preferably, the coupling agent comprises a silane coupling agent.

[0064] Preferably, the coupling agent comprises -Chloropropylmethoxysilane, vinylethoxysilane, vinyltri( -methoxyethoxy)silane, -Methacryloyloxypropyltrimethoxysilane, vinyltriacetoxysilane, -(2,3-Epoxypropyloxy)propyltrimethoxysilane, 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate, - any one of methacryloxypropyltrimethoxysilane, anilinemethyltriethoxysilane, octyltrimethoxysilane, or a combination of at least two thereof.

[0065] Preferably, the ethylene / The mass of the olefin copolymer is 100 parts, and the mass of the coupling agent is 0.01-3 parts, for example, it can be 0.02 parts, 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.8 parts, 1 parts, 1.5 parts, 2 parts or 2.5 parts, and more preferably 0.03-0.6 parts.

[0066] Preferably, the antioxidant includes any one of a hindered phenol antioxidant, a hindered amine antioxidant, and a phosphate antioxidant, or a combination of at least two of them.

[0067] Preferably, the antioxidant includes bis-2,2,6,6-tetramethylpiperidinol sebacate, -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetra( -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) pentaerythritol ester, bis(3,5-di-tert-butyl-4-hydroxypropionyl)hydrazine, 2,2'-oxalamido-bis(ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)) propionate, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine -2,4,6 (1H, 3H, 5H) trione, triethylene glycol bis (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate), 4,6-bis (octylthiomethyl) o-cresol, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate any one or a combination of at least two.

[0068] Preferably, the ethylene / The weight of the olefin copolymer is 100 parts, and the weight of the antioxidant is 0.01-1 parts, for example, 0.02 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts or 0.8 parts, and more preferably 0.02-0.5 parts.

[0069] Exemplarily, the method for preparing the packaging film comprises: The olefin copolymer, the cross-linking agent and the auxiliary cross-linking agent are mixed and melted, and then extruded and cast into a film to obtain the packaging adhesive film.

[0070] The packaging adhesive film provided by the present invention is prepared by high-temperature premixing of raw materials, melt extrusion, and film casting. The packaging adhesive film has a faster vulcanization reaction speed and a shorter auxiliary agent absorption time.

[0071] Preferably, the mixed material further comprises a coupling agent and / or an antioxidant.

[0072] Preferably, the film casting further includes the steps of cooling, slitting and winding.

[0073] In a fifth aspect, the present invention provides a solar cell assembly, wherein the solar cell assembly comprises the ethylene / At least one of an olefin copolymer or the encapsulation film as described in the third aspect.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] The ethylene / In the olefin copolymer, the surface roughness is designed to give it a special microstructure, a narrow molecular weight distribution and a low soluble content. Olefin copolymers are used in encapsulation films, which shorten the absorption time of additives and improve the vulcanization reaction speed and cross-linking degree of the encapsulation films. The encapsulation films made from them achieve performance optimization of polymer particles in photovoltaic application scenarios and meet the application requirements in solar cell modules. DETAILED DESCRIPTION

[0076] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0077] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0078] "Optionally" or "either" means that the subsequently described matter or event can or cannot occur, and that the description includes instances where the event occurs and instances where it does not.

[0079] In the following specific embodiments of the present invention, the specific information of the materials for which the preparation method is not provided is as follows, all of which are commercially available chemicals:

[0080] Tert-butyl peroxy 2-ethylhexyl carbonate, Akzo Nobel, purity > 95%;

[0081] Triallyl isocyanurate, Acros, purity 98%;

[0082] -Methacryloxypropyltrimethoxysilane, Aladdin, purity 95%;

[0083] -(2,3-Epoxypropyl)propyltrimethoxysilane, Aladdin, purity 95%;

[0084] Sebacate bis-2,2,6,6-tetramethylpiperidinol ester, Aladdin, purity 95%;

[0085] Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, Acros, purity 95%;

[0086] -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, namely antioxidant 1076, ark, purity 95%;

[0087] Four( -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) pentaerythritol ester, namely antioxidant 1010, commercially available;

[0088] 1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, Acros, purity 95%;

[0089] Tert-amyl peroxycarbonate, ark, purity 95%;

[0090] Trimethylolpropane triacrylate, Aladdin, purity 98%;

[0091] Antioxidant 1076, Lianlong New Materials Co., Ltd., industrial grade;

[0092] Antioxidant 1010, Lianlong New Materials Co., Ltd., industrial grade;

[0093] 1-Octene, Aladdin, purity 99%;

[0094] 1-Butene, Aladdin, purity 99%;

[0095] Ethylene, open torch gas, purity 99.99%;

[0096] Methylaluminoxane, Akzo Nobel, 10 wt% toluene solution;

[0097] Dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, Jiangsu Xinnoko Catalyst Co., Ltd., purity 98%;

[0098] Dimethylsilyl tert-butylamine tetramethylcyclopentadiene titanium dichloride, Suzhou Yuanqi Material Technology Co., Ltd., purity 98%;

[0099] n-Octane, Shanghai Aladdin Biochemical Technology Co., Ltd., purity >99.5%;

[0100] n-Pentane, Shanghai Aladdin Biochemical Technology Co., Ltd., purity > 99.5%

[0101] Alkane solvent Isopar E, Tianjin Tairong, industrial grade;

[0102] Ethanol, Tianjin Tairong, industrial grade;

[0103] Ethylene glycol, Tianjin Tairong, industrial grade.

[0104] Example 1

[0105] An ethylene-octene copolymer is prepared by the following method:

[0106] In a 2.0 L continuous process reactor, n-hexane solvent was injected at 4.50 kg / h, 1-octene was injected at 2.82 kg / h, and the reactor temperature was controlled at 150°C. At the same time, the main catalyst dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride (0.35 μmol / min) and the co-catalyst 10 wt% methylaluminoxane toluene solution (wherein the methylaluminoxane flow rate was 3.6 μmol / min) were injected into the reactor. Then, ethylene was introduced into the reactor at 1.38 kg / h and the pressure was controlled at 60 bar for continuous operation. After stable operation, the obtained polymer solution is heated to 280°C through a heater from the reactor outlet and then enters a primary devolatilizer (temperature 220°C, pressure 1 barG), then heated to 280°C and transported to a secondary devolatilizer (temperature 220°C, pressure 3 kPaA) through a gear pump, and the polymer melt is injected into a coagulation bath of a pelletizing system, and pelletized by drawing for 9 meters at a rate of 3 m / min to obtain the ethylene-octene copolymer; the mass content of IsoparE (isoalkanes) in the coagulation bath is 10%, the mass content of ethanol is 10%, and the mass content of water is 80%.

[0107] Example 2

[0108] An ethylene-butene copolymer is prepared by the following method:

[0109] In a 2.0 L continuous process reactor, n-octane solvent was injected at 5.0 kg / h, 1-butene was injected at 2.67 kg / h, and the reactor temperature was controlled at 152°C. At the same time, the main catalyst dimethylsilyl tert-butylamine tetramethylcyclopentadiene titanium dichloride (0.48 μmol / min) and the co-catalyst 10 wt% methylaluminoxane toluene solution (wherein the methylaluminoxane flow rate was 48 μmol / min) were injected into the reactor. Then, ethylene was introduced into the reactor at 1.55 kg / h and the pressure was controlled to be 42 bar for continuous operation. After stable operation, the obtained polymer solution is heated to 280°C through a heater from the reactor outlet and then enters a primary devolatilizer (temperature 200°C, pressure 1 barG), then heated to 280°C and transported to a secondary devolatilizer (temperature 200°C, pressure 3 kPaA) through a gear pump, and then the polymer melt is injected into a coagulation bath of a pelletizing system, and pelletized by stretching for 10 meters at a rate of 5 m / min to obtain the ethylene-butene copolymer; the mass content of toluene in the coagulation bath is 10%, the mass content of ethanol is 10%, and the mass content of water is 80%.

[0110] Example 3

[0111] An ethylene-butene copolymer, which is different from Example 2 only in the components of the coagulation bath, wherein the mass content of toluene in the coagulation bath is 5%, the mass content of ethanol is 30%, and the mass content of water is 65%.

[0112] Example 4

[0113] An ethylene-octene copolymer is different from Example 1 only in the components of the coagulation bath. The mass content of n-pentane in the coagulation bath is 15%, the mass content of ethylene glycol is 25%, and the mass content of water is 60%.

[0114] Comparative Example 1

[0115] An ethylene-octene copolymer, which differs from Example 1 only in the composition of the coagulation bath, which is 100% water.

[0116] Comparative Example 2

[0117] An ethylene-butene copolymer, which differs from Example 2 only in the composition of the coagulation bath, which is 100% water.

[0118] Comparative Example 3

[0119] An ethylene-butene copolymer, which is different from Example 2 only in the components of the coagulation bath, wherein the mass content of toluene in the coagulation bath is 10%, and the mass content of water is 90%.

[0120] Comparative Example 4

[0121] An ethylene-butene copolymer, which is different from Example 2 only in the components of the coagulation bath, wherein the mass content of ethanol in the coagulation bath is 10%, and the mass content of water is 90%.

[0122] Comparative Example 5

[0123] An ethylene-butene copolymer, which is different from Example 2 only in the components of the coagulation bath, wherein the mass content of toluene in the coagulation bath is 40%, the mass content of ethanol is 10%, and the mass content of water is 50%.

[0124] The performance test method of the copolymer is as follows:

[0125] (1) Weight average molecular weight M w , number average molecular weight M n , molecular weight distribution PDI is analyzed by GPC-IR instrument of polymer char, which has three MIXED columns connected in series, with a size of 300×7.5 mm; equipped with three detectors, infrared, viscosity and laser, and usually uses IR5 MCT polyolefin-specific infrared detector for detection; the sample is automatically injected with 8 mL trichlorobenzene solvent in the high temperature zone (160°C) of the instrument's automatic sampler, and after shaking and dissolving for one hour, 200 μL is extracted for testing, the infrared detector temperature is 150°C, the molecular weight standard used is PS, and the monomer marking line uses a series of ethylene / Olefin copolymers are established; PDI is M w / M n .

[0126] (2) Soluble matter content

[0127] The analysis was performed using a polymer char TGIC instrument: the sample was dissolved in trichlorobenzene at 165°C and passed through a TGIC column, then programmed to cool to 40°C (20°C / min). Part of the polyolefin structure adhered to the column due to adsorption and crystallization with the graphite column, and flushed at a flow rate of 0.5 mL / min, where the mobile phase consisted of 2 g of BHT (2,6-di-tert-butyl-p-cresol) dissolved in 4 L of trichlorobenzene. The soluble part was flushed to the detector IR5 for detection, and the temperature was raised to 165°C at a rate of 2°C / min. The molecules attached to the column were washed out in sequence according to their crystallization ability and the number of short side chains. The soluble content is defined as the mass fraction of the mass of the part flushed to the detector for detection in the total mass of the sample.

[0128] (3) Surface roughness Λ BET

[0129] It is calculated by the formula shown in formula I. In formula I, the density of the copolymer is tested by a density meter test. The specific method is as follows: the copolymer pressed sheet to be tested is cut into samples, and the density is tested using a density meter Mettler XS204, using an immersion method, and the immersion liquid is anhydrous ethanol. The test environment temperature is 23±2℃, and the test temperature needs to be internally calibrated. The sample mass is greater than 1 g and there are no bubbles. The mass of the sample in the air and the mass in the immersion liquid are weighed respectively, and the density is calculated and derived by the Archimedean principle.

[0130] The average particle size of the copolymer particles is obtained by testing and calculating with a digital vernier caliper. Specifically, the maximum diameter of the particles (recorded as the X direction) and the diameters in the Y and Z directions perpendicular to the maximum diameter are measured with a digital vernier caliper, and the average of the three is calculated and recorded as the particle size of one particle. The measurement is repeated for 50 particles, and the average value is taken and recorded as the average particle size of the batch of copolymer particles.

[0131] The BET specific surface area was obtained by static volumetric method and tested by BET multi-point method on BSD-660M A6S B6M surface analyzer. The adsorbent was N2 at 77.3 K. In-situ degassing mode was adopted. The degassing conditions were 50 °C, 60 min, and the gas injection volume in the low-pressure stage was 0.5 cm 3 , the leveling condition is 0.1% Pr, 120 s.

[0132] The test results are summarized in Table 1.

[0133] Table 1

[0134]

[0135] Application Example 1

[0136] A packaging film, the raw materials for its preparation are as follows: 1000 g of the ethylene-octene copolymer obtained in Example 1, 9 g of tert-butyl peroxide 2-ethylhexyl carbonate, 5 g of triallyl isocyanurate, 2 g -Methacryloxypropyltrimethoxysilane, 1 g -(2,3-epoxypropyloxy)propyltrimethoxysilane, 1 g of bis-2,2,6,6-tetramethylpiperidinol sebacate, 1 g of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite and 1 g -(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester.

[0137] The preparation method of the encapsulation film is as follows:

[0138] The above-prepared raw materials are mixed and heated to 50°C for uniform mixing, and the extruder parameters are adjusted. There are 8 sections from the feed port to the die head, and the temperatures of sections 1-8 are 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, respectively. The screw speed is 45 rpm, the traction speed is 0.7 rpm, and the winding speed is 1.3 rpm. After extrusion, cast film, cooling, slitting and winding processes, the encapsulation film is obtained, and the film thickness is 0.6 mm.

[0139] Application Example 2

[0140] A packaging film, the raw materials for its preparation are as follows: 1000 g of the ethylene-butene copolymer obtained in Example 2, 6 g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 g of tert-amyl peroxycarbonate, 4 g of trimethylolpropane triacrylate, 2 g -Methacryloxypropyltrimethoxysilane, 1 g -(2,3-Epoxypropyloxy)propyltrimethoxysilane, 1 g of bis-2,2,6,6-tetramethylpiperidinol sebacate, 1 g of antioxidant 1076 and 1 g of antioxidant 1010.

[0141] The preparation method of the encapsulation film is as follows:

[0142] The prepared raw materials were heated to 50°C and mixed evenly, and the extruder parameters were adjusted. There were 8 sections from the feed port to the die head, and the temperatures of sections 1-8 were 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, respectively. The screw speed was 45rpm, the pulling speed was 0.7 rpm, and the winding speed was 1.3 rpm. After extrusion, cast film, cooling, slitting and winding processes, the encapsulation film was obtained, and the film thickness was 0.6 mm.

[0143] Application Example 3

[0144] A packaging film, which differs from Application Example 2 only in that the ethylene-butene copolymer is replaced by the ethylene-butene copolymer provided in Example 3 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 2.

[0145] Application Example 4

[0146] A packaging film, which differs from Application Example 1 only in that the ethylene-octene copolymer is replaced by the ethylene-octene copolymer provided in Example 4 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 1.

[0147] Comparative application example 1

[0148] A packaging film, which differs from Application Example 1 only in that the ethylene-octene copolymer is replaced by the ethylene-octene copolymer provided in Comparative Example 1 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 1.

[0149] Comparative Application Example 2

[0150] A packaging film, which differs from Application Example 2 only in that the ethylene-butene copolymer is replaced by the ethylene-butene copolymer provided in Comparative Example 2 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 2.

[0151] Comparative Application Example 3

[0152] A packaging film, which differs from Application Example 2 only in that the ethylene-butene copolymer is replaced by the ethylene-butene copolymer provided in Comparative Example 3 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 2.

[0153] Comparative Application Example 4

[0154] A packaging film, which differs from Application Example 2 only in that the ethylene-butene copolymer is replaced by the ethylene-butene copolymer provided in Comparative Example 4 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 2.

[0155] Comparative Application Example 5

[0156] A packaging film, which differs from Application Example 2 only in that the ethylene-butene copolymer is replaced by the ethylene-butene copolymer provided in Comparative Example 5 of equal mass; other materials, amounts and preparation methods are the same as those in Application Example 2.

[0157] The copolymer and packaging film were tested as follows:

[0158] (1) Additive absorption time

[0159] The copolymer samples of the above examples and comparative examples were placed in a 50 cm×80 cm ziplock bag, with a sample mass of 2 kg, and an additive package with a fixed composition and content was added: 30 g of tert-butyl peroxy 2-ethylhexyl carbonate, 10 g of triallyl isocyanurate, 4 g -Methacryloxypropyltrimethoxysilane. After the ziplock bag is tightly sealed, shake the ziplock bag to evenly mix the resin sample and the additive package, then place the ziplock bag in a 50°C oven, observe the drying of the small droplets of additives in the bag over time, and record the time when the droplets are completely dry, which is the additive absorption time. The shorter the time, the faster the copolymer absorbs the additive.

[0160] (2) Vulcanization performance

[0161] The characteristic vulcanization time Ts1, Ts2, Ts3 of the copolymer was tested using a rotorless vulcanizer (Alpha, MDR) at 145°C for 15 min. 10 , T 90 , MH.

[0162] Ts1 and Ts2: time for the torque to reach 1 dN·m and 2 dN·m respectively; T 90 T is the positive vulcanization time, that is, the time required to achieve 90% vulcanization; 10 It is the time required to reach 10% vulcanization; MH is the maximum torque under the test conditions, which characterizes the shear modulus, hardness and crosslinking density of the rubber.

[0163] (3) Degree of cross-linking

[0164] The cross-linking degree test method refers to the China Photovoltaic Industry Association standard T / CPIA 0006-2017 "Copolyolefin Film for Photovoltaic Module Encapsulation". Sample preparation: After taking two pieces of film and stacking them, laminating them with a laminator, weigh 0.5±0.01 g, cut them into small particles with a size of less than 3 mm×3 mm, and prepare 3 samples for each group. After extracting with xylene at 140℃ for 5 hours, put them in a 140℃ vacuum oven and dry them to constant weight.

[0165] The test results are summarized in Table 2.

[0166] Table 2

[0167]

[0168] It can be seen from the test results of Table 1 and Table 2 that the ethylene / The olefin copolymer has a specific surface roughness, which can be obtained by etching the surface of the copolymer with a specific coagulation bath solvent; at the same time, the copolymer has a narrower PDI distribution and a lower soluble content, and absorbs the additives faster, so that the prepared photovoltaic encapsulation film has a fast cross-linking and vulcanization reaction speed and a high degree of cross-linking.

[0169] It can be seen from Application Examples 2 and 3 that the present invention can achieve better improvement of the surface roughness of the particles by further increasing the good solvent content in the coagulation bath, thereby better shortening the absorption time of the additive; in addition, by further increasing the good solvent content, the grading effect can be better achieved, thereby reducing the soluble matter content, which is beneficial to the improvement of the cross-linking vulcanization performance.

[0170] It can be seen from Application Example 1 and Comparative Application Example 1, as well as Application Example 2 and Comparative Application Example 2 that when the coagulation bath solvent is only water, the surface roughness of the copolymer decreases, the molecular weight distribution is wider, the soluble content increases, and the vulcanization time of the obtained film is prolonged and the degree of cross-linking is low, which makes it difficult to meet the actual application needs of solar cell modules and downstream film manufacturers.

[0171] It can be seen from Application Example 2 and Comparative Application Example 4 that when the coagulation bath solvent is only a combination of water and a poor solvent, since the ternary mixed solvent system of the present invention is not adopted and the polymer is not dissolved into small molecules by a good solvent, the surface roughness of the copolymer is reduced, while the molecular weight distribution becomes wider, the soluble matter content increases, and the vulcanization time of the obtained film and the cross-linking degree of the final product are still insufficient.

[0172] It can be seen from Application Example 2 and Comparative Application Example 3 that when the coagulation bath solvent is only a combination of water and a good solvent, due to the failure to use the ternary mixed solvent system of the present invention, the surface roughness of the copolymer is reduced, the molecular weight distribution becomes wider, the soluble matter content is increased, and the vulcanization time of the obtained film and the cross-linking degree of the final product are still insufficient.

[0173] It can be seen from Application Example 2 and Comparative Application Example 5 that when the good solvent content in the coagulation bath solvent is too high, although the good solvent grades the polymer and narrows the molecular weight distribution, the polymer suffers serious dissolution loss in the solvent, resulting in a significant decrease in the molecular weight, making the cross-linking degree of the final film significantly low.

Claims

1. Ethylene / Olefin copolymer, characterized in that The ethylene / The weight average molecular weight of the olefin copolymer is 48600-130000 g / mol, and the ethylene / The surface roughness of olefin copolymers is 80-140; The calculation formula of the surface roughness is shown in Formula I: Formula I; in, Indicates the surface roughness, Indicates ethylene / Density of olefin copolymers, d avg Indicates ethylene / The average particle size of the olefin copolymer particles, A BET It means ethylene obtained by BET test method / Specific surface area of ​​olefin copolymer particles; The average particle size is measured and calculated by the following method, the method comprising: measuring the ethylene / The maximum diameter of the olefin copolymer particle is recorded as the diameter in the X direction, and the diameters perpendicular to the maximum diameter are measured and recorded as the diameter in the Y direction and the diameter in the Z direction respectively; the average values ​​of the diameters in the X direction, the Y direction and the Z direction are calculated and recorded as the diameter of an olefin copolymer particle. The particle size of the olefin copolymer particles: the particle sizes of 50 particles are tested and the average value is recorded as the average particle size.

2. Ethylene according to claim 1 / Olefin copolymer, characterized in that The ethylene / The molecular weight distribution of the olefin copolymer is 2.3-2.

6.

3. Ethylene according to claim 1 / Olefin copolymer, characterized in that Said The olefins include any one of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene, or a combination of at least two thereof.

4. An ethylene / A method for preparing an olefin copolymer, characterized in that: The preparation method comprises: Ethylene, The olefin is polymerized in the presence of a catalyst to obtain a polymer melt; the polymer melt is melt-extruded, injected into a coagulation bath of a ternary solvent system, and then pelletized to obtain the ethylene / Olefin copolymers; The ternary solvent system includes a combination of water, a poor solvent and a good solvent; The mass content of water in the ternary solvent system is 50-82%, the mass content of the poor solvent is 8-32%, and the mass content of the good solvent is 4-20%; The poor solvent is a C2-C20 alcohol solvent, the good solvent is an aliphatic solvent and / or an aromatic solvent, the aliphatic solvent is selected from any one or a combination of at least two of n-butane, isobutane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, and isoparaffin solvents, and the aromatic solvent is selected from any one or a combination of at least two of benzene, toluene, xylene, halogenated benzenes, halogenated toluenes, and halogenated xylenes.

5. The preparation method according to claim 4, characterized in that: The poor solvent includes any one of ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, n-decanol, dodecanol, tetradecanol, and hexadecanol, or a combination of at least two thereof.

6. The preparation method according to claim 4, characterized in that: The method for preparing the polymer melt comprises: reacting a solvent, Olefins, a main catalyst and a co-catalyst are mixed, ethylene is introduced to carry out polymerization reaction, and volatilization is carried out to obtain the polymer melt; The main catalyst includes a metallocene catalyst and / or a post-metallocene catalyst; The co-catalyst comprises any one or a combination of at least two of alkyl aluminum, organic boron compound, and alkyl aluminoxane; The polymerization reaction temperature is 100-200°C and the pressure is 10-100 bar; The devolatilization temperature is 180-300°C.

7. A packaging film, characterized in that: The raw materials for preparing the encapsulation film include the ethylene / Olefin copolymers.

8. The packaging film according to claim 7, characterized in that: The preparation raw materials also include a cross-linking agent and a co-cross-linking agent; The cross-linking agent includes an organic peroxide, and the auxiliary cross-linking agent includes a multifunctional olefin-containing compound.

9. The packaging film according to claim 8, characterized in that: The ethylene / The mass of the olefin copolymer is 100 parts, and the mass of the cross-linking agent is 0.1-5 parts; and / or, with the ethylene / The weight of the olefin copolymer is 100 parts, and the weight of the auxiliary cross-linking agent is 0.1-5 parts.

10. A solar cell module, characterized in that: The solar cell assembly comprises the ethylene / At least one of an olefin copolymer or a packaging film as described in any one of claims 7 to 9.

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