A process for the preparation of a polyolefin elastomer and its use

Abstract

The application discloses a preparation method and application of a polyolefin elastomer, and relates to the following steps: in the first step, under the action of a first catalyst, ethylene, a functional monomer A and a functional monomer B are subjected to a copolymerization reaction in a solvent to obtain an oligomer polar molecular chain; in the second step, under the action of a second catalyst and a cocatalyst, alpha-olefin is polymerized to obtain a polyolefin elastomer melt, then the polyolefin elastomer melt is subjected to devolatilization and drying, and finally the polyolefin elastomer copolymer is obtained through single-screw extrusion. The polyolefin elastomer prepared by the preparation method has excellent polarity, can be applied in different fields, is especially suitable for preparing a photovoltaic adhesive film, and can ensure that a battery assembly can maintain high power generation for a long time.

Description

Technical Field

[0001] This invention patent belongs to the field of polymer material preparation technology, specifically relating to a method for preparing and applying a polyolefin elastomer. Background Technology

[0002] Polyolefin elastomers (POEs), due to their unique molecular chain structure, exhibit characteristics of polyolefins with a carbon-carbon backbone, possessing a certain degree of crystallinity. The addition of a certain amount of α-olefin monomers weakens the crystallinity of the molecular chain, giving them elastomer characteristics. Therefore, they possess excellent elasticity, transparency, and low-temperature resistance. Simultaneously, because their molecular chain has a saturated structure, they also have extremely high volume resistivity and water vapor barrier properties, making them widely used in toughening and modification of engineering plastics, shoe material foaming, and encapsulation films. Especially in the encapsulation materials field, the usage of POE is increasing year by year. In the current photovoltaic film industry, EVA holds over 70% of the market share due to its excellent heat-sealing and processing properties. However, vinyl acetate is prone to hydrolysis under light, oxygen, and humid heat environments, producing acetic acid, which corrodes the surface of the solar cells and solder ribbons. It also causes a large number of freely moving Na ions inside the module, resulting in a decrease in power generation. Looking at the development trend of solar cells, the power of P-type solar cells is gradually reaching its limit, while the power generation efficiency of n-type solar cells, especially heterojunction cells, is constantly making breakthroughs. The requirements for the performance of the encapsulant film are becoming increasingly higher, and the disadvantages of EVA materials are gradually being exposed. The proportion of POE materials used will continue to increase. However, POE materials also have some problems, such as low polarity, slow absorption of additives, easy precipitation of additives to the surface of the encapsulant film, and low bonding strength with new solar cells.

[0003] Currently, there are two main methods for preparing functionalized polar polyolefin elastomers: (1) direct polymerization and (2) chemical grafting. Direct polymerization refers to the use of a specific catalyst to catalyze the copolymerization of ethylene, α-olefins, and polar α-olefins to prepare functionalized polyolefins. Patent CN114316096 A provides a functionalized polyolefin elastomer and its preparation method. In the presence of a vanadium-based catalyst, ethylene, α-olefins, and vinyl norbornene are used as monomers to perform a copolymerization reaction to prepare a polyolefin elastomer, which is then subjected to a functionalization reaction to obtain the functionalized polyolefin elastomer. Since the polymerization reaction requires two steps, the economic benefits are poor, and the functionalized polyolefin elastomer prepared is only suitable for use in fields such as modification, which limits its application scope. Patent CN115073672 A provides a method for preparing low-odor POE grafted maleic anhydride. In the presence of an initiator, maleic anhydride, POE resin and additives are mixed and extruded, and then granulated by passing carbon dioxide through to obtain low-odor POE grafted maleic anhydride. This product is suitable as a compatibilizer to improve compatibility with polar polymers and achieve toughening, but it is only suitable for use in the field of modification, which limits its scope of application.

[0004] In summary, there is an urgent need in this field to obtain a functional polar polyolefin elastomer copolymer that can improve the absorption rate of additives, reduce the precipitation of additives in products, have excellent comprehensive performance in photovoltaic power generation applications, increase the adhesion strength of polyolefin elastomers to glass and metals, and ensure that battery modules, especially new battery modules (heterojunction, perovskite) modules, maintain a high level of power generation for a long time. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a method and application for polyolefin elastomers. This invention addresses the problems from the perspective of the inherent defects of polyolefin elastomers, improves the polarity of the material, makes it less prone to additive precipitation, has strong adhesion, and can be used in the photovoltaic power generation field, exhibiting excellent overall performance.

[0006] To achieve the above objectives, the present invention provides a method for preparing a polyolefin elastomer, the method comprising the following steps:

[0007] Step 1: Under the action of the first catalyst, ethylene, functional monomer A and functional monomer B are copolymerized in a solvent to obtain low polymer polar molecular chains; Step 2: Under the action of the second catalyst and co-catalyst, α-olefin polymerization is carried out to obtain polyolefin elastomer melt, which is then devolatilized and dried, and finally extruded and granulated by an extruder to obtain polyolefin elastomer copolymer.

[0008] The functional monomer A contains both carbon-carbon double bonds and ether bonds, and has a molecular weight of 50-500 g / mol, preferably 50-300 g / mol, and more preferably 60-200 g / mol.

[0009] Preferably, the functional monomer A has a carbon-carbon double bond at its end, the ether bond is one or more, the functional monomer B has a carbon-carbon double bond, and also contains one or more of ester group, epoxy group, amino group, amide group or isocyanate group, and the molecular weight is 50 to 500 g / mol, preferably 60 to 400 g / mol, more preferably 60 to 300 g / mol;

[0010] Preferably, the end of the functional monomer B contains a carbon-carbon double bond.

[0011] Preferably, the functional monomer A is an alkyl alkenyl ether, an alcohol alkenyl ether, an epoxy alkenyl ether, etc., specifically including but not limited to allyl ethyl ether, acrylaldehyde dimethyl acetal, allyl glycidyl ether, allyl butyl ether, 2-ethyl-2-vinyl-1,3-dioxocyclopentane, 2-allyloxytetrahydropyran, glycidyl acrylate, 3-butenal diethyl acetal, 2,5,8,11-tetraoxatetradecene, propylene glycol monoallyl ether, ethylene glycol monoallyl ether, vinyl isobutyl ether, vinyl butyl ether, etc.

[0012] Preferably, the functional monomer B is an acrylate, acrylamide, etc., specifically including but not limited to methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 1-[2-(aminooxy)ethoxy]ethylene, acrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, N-isopropylacrylamide, allylformamide, dimethylaminopropylacrylamide, butoxymethylacrylamide, allyl isocyanate, allyl urea, 3,4-epoxy-1-butene, methyl acrylamide acetate, ethylene oxide-2-ylmethacrylate, etc.

[0013] In this invention, the first catalyst is a nickel phosphosulfonate complex, with the structure shown below:

[0014]

[0015] R1-R8 are each independently H, C1-C20 alkyl or C1-C10 alkoxy or halogen substituent or aryl, preferably each independently H, C1-C10 linear, branched, cyclic alkyl or C1-C6 alkoxy, halogen or C6-C15 aryl, more preferably each independently H, methoxy, ethoxy, tert-butyl, phenyl, C1-C3 alkyl-substituted phenyl, Cl or Br;

[0016] Preferably, the first catalyst has the following structure:

[0017]

[0018]

[0019] Preferably, the amount of the first catalyst is 0.05 to 8 ppm, more preferably 0.1 to 7 ppm, based on the total mass of the reaction feed.

[0020] The second catalyst is a metallocene complex, with the structure shown below:

[0021]

[0022] Wherein, R1 and R2 may be the same or different, and each is independently selected from hydrogen, methyl, isopropyl, and tert-butyl. Preferably, R1 is selected from methyl, isopropyl, and tert-butyl, and R2 is selected from hydrogen, methyl, and tert-butyl.

[0023] M is one or more of group IVB, VB, VIIB, and VIII transition metal atoms, preferably group IVB and / or group VB transition metal atoms, and more preferably zirconium;

[0024] Specifically, the second catalyst has one or more of the following structures:

[0025]

[0026] In this invention, the amount of the second catalyst is 0.05 to 5 ppm, preferably 0.1 to 3 ppm, based on the total mass of the reaction feed.

[0027] In this invention, the co-catalyst is an alkylaluminoxane or an alkyl-modified aluminoxane, preferably one or more of methylaluminoxane, isobutyl-modified aluminoxane, and octyl-modified aluminoxane, preferably octyl-modified aluminoxane. The amount of co-catalyst used is 0.1 to 10 ppm based on the total mass of the reaction feed.

[0028] In this invention, based on the total mass of the reacting monomers, the amount of ethylene is 23-48% by weight, preferably 28-46% by weight; the amount of α-olefin is 50-75% by weight, preferably 52-70% by weight; the amount of functional monomer A is 0.1-2% by weight, preferably 0.5-1.7% by weight; and the amount of functional monomer B is 0.05-2% by weight, preferably 0.2-1.5% by weight.

[0029] In a preferred embodiment of the present invention, the α-olefin is one or a combination of several selected from propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and 1-hexadecene, preferably 1-butene, 1-hexene, and 1-octene;

[0030] The solvent is one or more of C6-C10 straight-chain alkanes, isoalkanes, cycloalkanes, and aromatic alkanes, preferably one of n-hexane, cyclohexane, methylcyclohexane, n-heptane, isoheptane, n-octane, isooctane, n-decane, toluene, xylene, and C8-C10 mixed isoalkanes (IsoparE).

[0031] In this invention, functional monomer A and functional monomer B are first dissolved in a solvent to form a mixed solution and preheated. The ratio of monomer to solvent by volume is 1:1 to 5, and the preheating temperature is 30 to 70°C.

[0032] In this invention, the conditions for the first step polymerization reaction include: a temperature of 70–140°C, preferably 80–120°C; a pressure of 1–6 MPaG, preferably 1.5–5 MPaG; and a time of 0.1–3 h, preferably 0.5–2 h. The conditions for the second step polymerization reaction include: a temperature of 120–220°C, preferably 140–200°C; a pressure of 1–6 MPaG, preferably 1.5–5 MPaG; and a time of 0.1–2 h, preferably 0.2–1 h.

[0033] The pressure described in this invention is absolute pressure.

[0034] In this invention, the prepared functional polar polyolefin elastomer copolymer contains ethylene structural units, α-olefin structural units, structural unit A, and structural unit B; wherein, based on the total weight of the polymer, the content of the ethylene structural units is 63-90% by weight, the content of the α-olefin structural units is 8-35% by weight, the content of structural unit A is 0.1-2% by weight, and the content of structural unit B is 0.05-2% by weight.

[0035] In this invention, the weight-average molecular weight (Mw) of the polyolefin elastomer is 40,000 to 120,000, with a molecular weight distribution < 4; the density is 0.845 to 0.935 g / cm³. 3 The residual organic solvent content is 50-500 ppm; the melt index of 2.16 kg at 190℃ is 0.1-40 g / 10 min; and the melting point is 40-110℃.

[0036] In this invention, the polyolefin elastomer prepared is a polar elastomer, which can be applied in polymer modified materials, polymer blended foam materials, polymer wire and cable materials, polymer medical materials, polymer solar power generation materials, photovoltaic materials, etc., preferably in the fields of photovoltaic power generation and photovoltaic films.

[0037] Compared with the prior art, the positive effects of the present invention are as follows:

[0038] (1) The functional polar polyolefin elastomer prepared by the present invention is particularly suitable for use as a photovoltaic encapsulant film, which can reduce the potential-induced degradation of the front and back sides of the battery module. This is mainly because the oxygen atom in the ether bond is sp 3 Hybridization, in which two orbitals are sp from the adjacent carbon atom 3 Hybrid orbitals overlap to form σ bonds. The two unbonded orbitals contain two lone pairs of electrons, whose electron-donating conjugation effect is greater than the electron-withdrawing inductive effect. This allows them to adsorb metal cations. Under the influence of the potential difference, the metal cations are conducted along the molecular chain, preventing metal cations generated in the glass and the encapsulant from entering the battery surface. This reduces the occurrence of PID-s and PID-p degradation mechanisms in bifacial PERC cells. At the same time, the two lone pairs of electrons on the oxygen atom act as acceptors to form hydrogen bonds with water molecules, reducing the entry of water into the cell surface. This ensures that the cell is not corroded, reduces the occurrence of PID-c degradation mechanisms, and ensures that the cell has a high power generation capacity.

[0039] (2) By introducing groups with lone pairs of electrons or electrons, valence bonds are formed between the adhesive film and the glass with opposite charges to the bonded material, thereby improving the bonding strength between the adhesive film and the battery cell.

[0040] (3) By introducing polar groups, the polarity of polyolefin elastomers can be increased, the compatibility with polar resins can be improved, and the absorption time of additives can be reduced, as well as the degree of additive precipitation. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] Raw material source and specifications:

[0043]

[0044]

[0045]

[0046] The polymers obtained through the above examples and comparative examples were tested using the following methods, and the test indicators are listed in Table 1.

[0047] Copolymer index testing methods:

[0048] The polymerization activity is calculated as the ratio of the weight of the dried polymer product obtained from the polymerization reaction to the molar number of transition metal compounds (catalysts) added during the reaction process.

[0049] Polymer molecular weight (Mw) and polymer dispersion index (PDI) were determined by high-temperature gel permeation chromatography (PL-GPC220) with 1,2,4-trichlorobenzene as the mobile phase and polystyrene as the standard at 150 °C. The standard concentration was 0.1 mg / mL, the solvent flow rate was 1.0 mL / min, and the standard parameters were K = 59.1 and α = 0.69, while the sample parameters were K = 14.1 and α = 0.70.

[0050] The polymer melt flow rate (MFR) is measured using a melt flow indexer (MI-4). Under test conditions of 190℃ and 2.16kg load, the weight of molten polymer extruded through a die with a length of 8mm and an inner diameter of 2.095mm within a specified time is the MFR, expressed in g / 10min.

[0051] Polymer density was tested using a densitometer (impregnation method). The mass of the sample suspended in air by a metal wire with a diameter no greater than 0.5 mm was weighed. The sample mass should not exceed 10 g, accurate to 0.1 mg, and the mass was recorded. The sample suspended by the thin metal wire was then immersed in a beaker filled with impregnation solution placed on a fixed support. The temperature of the impregnation solution should be 23℃ ± 2℃. Air bubbles adhering to the sample were removed using the thin metal wire. The mass of the sample in the impregnation solution was weighed, accurate to 0.1 mg.

[0052] The polymer metal content was tested using an inductively coupled plasma atomic emission spectrometer (ICP720-OES). A 4% dilute nitric acid solution was used to react with the sample at 80°C for 1 hour, and the mixture was then filtered before testing.

[0053] The volume resistivity of the polymer was measured using a high-resistivity meter (YG87-3) on a 100*100*0.6mm thin film laminated with the polymer.

[0054] The melting point Tm of the polymer was measured using a differential scanning calorimeter (DSC, with a scanning temperature range of 40-150℃ and a heating rate of 5℃ / min).

[0055] Residual polymer solvents were analyzed using headspace gas chromatography (GC 7890B) with a flame ionization detector (FID). The external standard method was used to determine the residual solvent content. A capillary column made of fused silica was used, with polyethylene glycol as the stationary phase and nitrogen at a flow rate of 5 mL / min as the carrier gas. The initial column temperature was 60 °C for 2 min, then increased to 80 °C at 5 °C / min, followed by a further increase to 250 °C at 15 °C / min, and held for 5 min. The vaporization chamber temperature was 200 °C, and the detector temperature was 260 °C. Headspace parameters were: heating time 60 min, heating temperature 150 °C, and injection volume 1 mL. Standard solutions with concentrations of 100, 400, 800, 1000, 2500, and 5000 mg / kg were prepared using the target solvent and triacetin. An external standard calibration curve was plotted with the peak area of ​​the analyte as the ordinate and the mass of the analyte in the standard solution as the abscissa. For sample analysis, weigh approximately 0.10 g of polymer into a 20 mL headspace vial, seal it, and weigh it accurately. Inject the sample for analysis according to the test conditions described above.

[0056] Polymer structural unit content was obtained by 13C NMR analysis. Specifically, 2.74 g of sample and tetrachloroethane-d2 containing 0.025 M Cr(AcAc)3 were added to a Nore II 1001-7 10 mm NMR tube. Oxygen was removed by manually purging the tube with nitrogen for 1 minute using a Pasteur pipette. The tube and its contents were heated to ~150 °C using a heating plate with minimal use of a heating gun to dissolve and homogenize the sample. The sample was thoroughly mixed immediately before analysis and should not be cooled before insertion into the heated NMR probe. This is necessary to ensure that the sample is homogeneous and representative of the whole sample. Data were collected using a Bruker 400 MHz spectrometer equipped with a Bruker cryopreservation probe. Data were acquired using 160 scans, a 6-second pulse repetition delay, and a sample temperature of 120 °C. All measurements were performed on a non-spin sample in locked mode. The sample was allowed to equilibrate for 7 minutes before data acquisition.

[0057] In this invention, the preparation method of the first catalyst is as follows:

[0058] (a) Using tetrahydrofuran as a solvent, the compounds shown in Formula I, Formula II and Formula III are dissolved in the solvent, and excess n-butyllithium is added to them to react and generate complex IV.

[0059] (b) Then, the complex IV shown was reacted with trans-chloro(1-naphthalene)bis(triphenylphosphine)-nickel in the presence of the dehydrogenating agent sodium hydride to give the desired nickel phosphonate complex.

[0060]

[0061]

[0062] In the method for preparing complex IV according to the present invention, the molar ratio of compound I, compound II, compound III and n-butyllithium in step (a) is 1:1:1:(1-2); the reaction temperature is -78 to 30°C, and the reaction time can be 6 to 12 h, for example 6 h, 8 h or 10 h.

[0063] In the method for preparing nickel phosphosulfonate complexes according to the present invention, the molar ratio of complex IV to dehydrogenating reagent can be 1:(1.5-3), more preferably 1:2; the reaction temperature in step (b) can be -80℃ to 30℃, and the reaction time can be 6-24h, preferably 8-12h, for example 8h, 10h or 12h.

[0064] In addition, the products obtained in each step can be separated in the following manner, wherein the eluent for separation can be composed of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate can be 50:1.

[0065] Preparation of PO-Ni-1 compounds:

[0066] (a) 2,4-Dichlorobenzenesulfonic acid (4.5 g, 20.4 mmol), 2-bromo-1,4-dimethoxynaphthalene (5.3 g, 20.4 mmol), and 3,5-diethylphenyl dichlorophosphine (4.2 g, 20.4 mmol) were added to a 100 mL round-bottom flask, and 50 mL of tetrahydrofuran was added. The temperature was lowered to -78 °C, and under nitrogen protection, excess n-butyllithium (30.6 mmol) was added to the round-bottom flask. The system was slowly restored to room temperature and reacted for 6 hours. The reaction solution was concentrated and purified by silica gel column chromatography (petroleum ether: ethyl acetate = 50:1 (v / v)) to obtain complex IV.

[0067] (b) At -78°C under nitrogen protection, NaH (0.58 g, 24 mmol) was added to 50 mL of tetrahydrofuran solution of complex IV (6.37 g, 12 mmol). The system was slowly restored to room temperature and reacted for 6 hours. The system was then cooled to -78°C, and trans-chloro(1-naphthyl)bis(triphenylphosphine)-nickel (8.96 g, mmol) was added. The system was slowly restored to room temperature and reacted for another 12 hours. After filtration, washing, and drying, complex PO-Ni-1 was obtained.

[0068] The preparation of complex PO-Ni-2 was the same as that of PO-Ni-1, and formula II was selected as 2-bromo-7-phenylnaphthalene (5.73 g, 20.4 mmol).

[0069] The preparation of complex PO-Ni-3 is the same as that of PO-Ni-1, with o-toluenesulfonic acid (3.41 g, 20.4 mmol) selected for Formula I and 2-bromo-7-phenylnaphthalene (5.73 g, 20.4 mmol) selected for Formula II.

[0070] The preparation of complex PO-Ni-4 is the same as that of PO-Ni-1, and formula II is selected as 2-bromo-7-methylnaphthalene (4.60 g, 20.4 mmol).

[0071] The preparation of the second catalyst Zr-1 is described in Example 10 of patent CN 111484574 A, and the preparation of Zr-2 is described in Example 9 of patent CN 111484574 A.

[0072] Example 1

[0073] Solution polymerization of ethylene / 3-butenal diethyl acetal / ethylene oxide-2-ylmethacrylate / 1-octene, with PO-Ni-1 as the first catalyst and Zr-1 as the second catalyst, and functional monomers A and B prepared as 50% by volume solutions.

[0074] A 10L reactor was heated to 50°C and evacuated for 2 hours. Nitrogen was then used for purging. After cooling to room temperature, ethylene was introduced for further purging. Under reaction conditions of 95°C and ethylene pressure of 3 MPaG, Isopar E (3600g) solvent, 201.3g of 3-butenal diethyl acetal solution, and 20.4g of ethylene oxide-2-ylmethacrylate solution were fed into a stirred reactor. The PO-Ni catalyst was separately injected into the reactor at a feed rate of 6.5mg, and the reaction was carried out for 30 minutes. The reactor was then heated to 130°C, and 1-octene (1050g) was introduced. 5.2mg of the second catalyst Zr-1 and 57.3mg of octyl-modified aluminoxane were added, and the reaction was continued for 20 minutes. After the reaction was completed, the depressurized polymer solution was heated to 200°C from the reactor outlet and then entered the first-stage devolatilization separator (temperature 190°C, pressure 2 barG). The reaction solution was then pumped to the second-stage devolatilization separator (220°C, pressure 2 barG) by a gear pump, and then entered the third-stage devolatilization separator (240°C, pressure 1 kPaA). The solution was then extruded by an extruder and finally pelletized by an underwater pelletizing system to obtain the olefin polymer.

[0075] The properties of the functional polar polyolefin elastomer copolymers prepared from ethylene structural units, α-olefin structural units, structural unit A, and structural unit B are shown in Table 1 below.

[0076] Example 2

[0077] Solution polymerization of ethylene / ethylene glycol monoallyl ether / 1-[2-(aminooxy)ethoxy]ethylene / 1-hexene, with PO-Ni-2 as the first catalyst and Zr-1 as the second catalyst.

[0078] The same solution polymerization method as in Example 1 was used, except that the functional monomer A was ethylene glycol monoallyl ether solution with a feed amount of 143.8 g, the functional monomer B was 1-[2-(aminooxy)ethoxy]ethylene solution with a feed amount of 43.2 g, the 1-hexene feed amount was 1200 g, the first catalyst PO-Ni-2 feed amount was 10.0 mg, the second catalyst Zr-1 feed amount was 3.2 mg, and the octyl-modified aluminum oxane feed amount was 35.3 mg. The properties of the prepared functional polar polyolefin elastomer copolymer are shown in Table 1 below.

[0079] Example 3

[0080] Solution polymerization of ethylene / glycidyl acrylate / allyl isocyanate / 1-butene, with PO-Ni-3 as the first catalyst and Zr-2 as the second catalyst.

[0081] The same solution polymerization method as in Example 1 was used, except that the functional monomer A was a glycidyl acrylate solution with a feed amount of 152.3 g, the functional monomer B was an allyl isocyanate solution with a feed amount of 14.3 g, the 1-butene feed amount was 1450 g, the first catalyst PO-Ni-3 feed amount was 15.3 mg, the second catalyst Zr-2 feed amount was 2.5 mg, and the octyl-modified aluminoxane feed amount was 45 mg. The properties of the prepared functional polar polyolefin elastomer copolymer are shown in Table 1 below.

[0082] Example 4

[0083] The same solution polymerization method as in Example 1 above was used, except that the first catalyst was PO-Ni-4, the feed amount of the first catalyst PO-Ni-4 was 4.8 mg, the second catalyst was Zr-2, and the functional monomer B was N-hydroxymethylacrylamide solution, the feed amount was 28.2 g. The properties of the prepared functional polar polyolefin elastomer copolymer are shown in Table 1 below.

[0084] Example 5

[0085] The same solution polymerization method as in Example 2 above was used, except that the feed amount of ethylene glycol monoallyl ether solution was 303.8 g, the feed amount of functional monomer B was n-propyl acrylate solution (24.8 g), the feed amount of the first catalyst PO-Ni-2 was 24.8 mg, and the feed amount of 1-hexene was 1600 g. The properties of the functional polar polyolefin elastomer copolymer prepared are shown in Table 1 below.

[0086] Example 6

[0087] The same solution polymerization method as in Example 3 above was used, except that the first catalyst was PO-Ni-2, the second catalyst was Zr-1, and the octyl-modified aluminum oxane feed amount was 60 mg. The properties of the functional polar polyolefin elastomer copolymer prepared are shown in Table 1 below.

[0088] Example 7

[0089] The same solution polymerization method as in Example 1 above was used, except that the first catalyst was PO-Ni-2 with a feed amount of 16.5 mg, the second catalyst was Zr-2, and the functional monomer A was an allyl butyl ether solution with a feed amount of 132.3 g. The properties of the prepared functional polar polyolefin elastomer copolymer are shown in Table 1 below.

[0090] Table 1: Comparison of properties of functional polar polyolefin elastomer copolymers prepared in the examples

[0091]

[0092]

[0093] Preparation of photovoltaic encapsulant film

[0094] A certain amount of the functional polar polyolefin elastomer prepared in Examples 1-7 was weighed and, after being fully absorbed by crosslinking agent, crosslinking aid, silane coupling agent, light stabilizer, ultraviolet absorber, and antioxidant, added to a single-screw casting extruder. The mixture was melted and plasticized, then injected into a T-die. The photovoltaic encapsulating film was obtained through melt extrusion, casting, cooling, slitting, and winding processes. The components of the encapsulating film are shown in Table 2.

[0095] Comparative Example 1 uses commercially available Dow 8669 as the matrix resin, with the same amount of other components.

[0096] Table 2

[0097]

[0098]

[0099] The encapsulating films obtained through the above embodiments and comparative examples were applied to the encapsulation of solar cell modules and evaluated using the following test methods. The evaluation results are listed in Table 3.

[0100] 1. Absorption time of adjuvants

[0101] Pour the resin and various additives into a transparent container, mix them evenly, and then place them in a 50°C oven. Observe whether there is any oily additive residue on the surface of the transparent container and the dryness of the particle surface. If there is no residue and the particle surface is dry, it means that the additives have been completely absorbed.

[0102] 2. Amount of additives released

[0103] Weigh 16g of the cast film and place it in 160g of anhydrous ethanol. Soak for 10min. Take 5g of anhydrous ethanol and perform liquid chromatography to analyze the triallyl isocyanurate (TAIC) dissolved in the anhydrous ethanol.

[0104] 3. Adhesion strength of glass / encapsulation film

[0105] The test method refers to the national standard GB / T2790 "Adhesives 180° Peel Strength Test Method Flexible Materials vs. Rigid Materials".

[0106] Sample preparation: Take 3.2mm thick ultra-white patterned tempered glass, double-layer encapsulating film, and TPT backplate, and place them into a vacuum laminator in the order of glass / encapsulating film / backplate. Laminate and cure at 150℃ for 18 minutes.

[0107] The test was conducted on a tensile testing machine at a tensile speed of 100 mm / min, and the tensile strength value was recorded.

[0108] 4. Component power test

[0109] The encapsulant films prepared in each embodiment and comparative example were used as the front and back encapsulant films for the same photovoltaic module. The photovoltaic module consisted of tempered glass, an upper encapsulant film, bifacial crystalline silicon solar cells, a lower encapsulant film, and tempered glass. Crosslinking was performed for 18 minutes at 150°C under vacuum and pressure using a laminator. The power change of the module before and after HAST aging (85°C, 85% RH, -1500V, 192h) was tested.

[0110] Table 3

[0111]

[0112] The polyolefin elastomer prepared by the method of the above embodiments can be applied to polymer modified materials, polymer foaming materials, polymer medical materials, polymer solar power generation materials, etc., and is especially suitable for use as a photovoltaic film.

Claims

1. A process for the preparation of a polyolefin elastomer, characterized in that, The method comprises the following steps: The first step is to copolymerize ethylene, functional monomer A and functional monomer B in a solvent under the action of a first catalyst to obtain an oligomer polar molecular chain; The second step is to introduce alpha-olefin polymerization under the action of a second catalyst and a cocatalyst to obtain a polyolefin elastomer melt, and then to perform devolatilization drying and granulation to obtain a polyolefin elastomer copolymer; The functional monomer A contains a carbon-carbon double bond and an ether bond, and has a molecular weight of 50-500 g / mol. The functional monomer B contains a carbon-carbon double bond, and further contains one or more of an ester group, an epoxy group, an amino group, an amide group or an isocyanate group, and has a molecular weight of 50-500 g / mol.

2. The production method according to claim 1, characterized by, The functional monomer A has a molecular weight of 50-300 g / mol.

3. The preparation method according to claim 2, characterized in that, The functional monomer A has a molecular weight of 60-200 g / mol.

4. The method of claim 1, wherein, The end of the functional monomer A contains a carbon-carbon double bond, and the ether bond is one or more.

5. The preparation method according to claim 1, characterized in that, The functional monomer B has a molecular weight of 60-400 g / mol.

6. The preparation method according to claim 5, characterized in that, The functional monomer has a molecular weight of 60-300 g / mol.

7. The preparation method according to claim 1, characterized in that, The end of the functional monomer B contains a carbon-carbon double bond.

8. The production method according to claim 1 or 2, characterized by, The functional monomer A includes one or more of an alkyl alkenyl ether, an alcohol alkenyl ether and an epoxy alkenyl ether.

9. The preparation method according to claim 8, characterized in that, The functional monomer A is selected from one or more of allyl ethyl ether, propionaldehyde dimethyl acetal, allyl glycidyl ether, allyl butyl ether, 2-ethyl-2-vinyl-1,3-dioxolane, 2-allyloxytetrahydropyran, glycidyl acrylate, 3-butenal diethyl acetal, 2,5,8,11-tetraoxatetradecane, propylene glycol monoallyl ether, ethylene glycol monoallyl ether, vinyl isobutyl ether and vinyl butyl ether.

10. The method of claim 1, wherein, The functional monomer B includes one or more of an acrylate and an acrylamide.

11. The method of claim 1, wherein, The functional monomer B includes one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 1-[2-(aminooxy)ethoxy]ethene, acrylamide, N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N-isopropyl acrylamide, allyl formamide, dimethylamino propyl acrylamide, butoxymethyl acrylamide, allyl isocyanate, 3,4-epoxy-1-butene, acrylamidoacetic acid methyl ester and oxetanyl methyl acrylate.

12. The method of claim 1, wherein, The first catalyst is a phosphorus sulfonic acid nickel complex, and has the following structure: wherein R1-R8 are each independently H, C1-C20 alkyl or C1-C10 alkoxy or halogen substituent or aryl.

13. The method of claim 12, wherein, R1-R8 are each independently H, C1-C10 linear, branched or cyclic alkyl or C1-C6 alkoxy, halogen or C6-C15 aryl.

14. The method of claim 13, wherein, R1-R8 are each independently H, methoxy, ethoxy, t-butyl, phenyl, C1-C3 alkyl-substituted phenyl, Cl or Br.

15. The method of claim 14, wherein, The first catalyst has the following structure:

16. The method of claim 1, wherein, The amount of the first catalyst is 0.05-8 ppm based on the total mass of the reaction feed.

17. The method of claim 16, wherein the method further comprises, The amount of the first catalyst is 0.1-7 ppm based on the total mass of the reaction feed.

18. The method of claim 1, wherein, The second catalyst is a metallocene complex, and has the following structure: wherein R1, R2 are the same or different, and each is independently selected from hydrogen, methyl, isopropyl, tert-butyl, and M is one or more of group IVB, VB, VIIB, VIII transition metal atoms.

19. The method of claim 18, wherein, R1 is selected from methyl, isopropyl, tert-butyl, and R2 is selected from hydrogen, methyl, tert-butyl. M is a group IVB and / or VB transition metal atom.

20. The method of claim 19, wherein, M is zirconium.

21. The method of claim 18, wherein, The second catalyst has one or more of the following structures:

22. The preparation method of claim 1, wherein the amount of the second catalyst is 0.05-5 ppm based on the total mass of the reaction feed.

23. The preparation method of claim 22, wherein the amount of the second catalyst is preferably 0.1-3 ppm based on the total mass of the reaction feed.

24. The method of claim 1, wherein, The co-catalyst is an alkyl aluminoxane or an alkyl-modified aluminoxane.

25. The method of claim 24, wherein, The co-catalyst is one or more of methyl aluminoxane, isobutyl-modified aluminoxane, and octyl-modified aluminoxane.

26. The method of claim 25, wherein, The co-catalyst is octyl-modified aluminoxane.

27. The method of claim 1, wherein, The amount of the co-catalyst is 0.1-10 ppm based on the total mass of the reaction feed.

28. The method of claim 1, wherein, The amount of the ethylene is 23-48 wt% based on the total mass of the reaction monomers; the amount of the α-olefin is 50-75 wt%; the amount of the functional monomer A is 0.1-2 wt%; and the amount of the functional monomer B is 0.05-2 wt%.

29. The method of claim 28, wherein, The amount of the ethylene is 28-46 wt% based on the total mass of the reaction monomers; the amount of the α-olefin is 52-70 wt%; the amount of the functional monomer A is 0.5-1.7 wt%; and the amount of the functional monomer B is 0.2-1.5 wt%.

30. The method of claim 1, wherein, The α-olefin is one or a combination of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and 1-hexadecene.

31. The method of claim 30, wherein, The α-olefin is 1-butene, 1-hexene, and 1-octene.

32. The method of claim 1, wherein, The solvent is one or more of C6-C10 straight-chain alkanes, isomeric alkanes, cycloalkanes, and aralkanes.

33. The method of claim 32, wherein the method further comprises, The solvent is one of n-hexane, cyclohexane, methylcyclohexane, n-heptane, isohexane, n-octane, isooctane, n-decane, toluene, xylene, and C8-C10 mixed isomeric alkanes.

34. The method of claim 1, wherein, The conditions of the first step of the polymerization reaction include a temperature of 70-140°C, a pressure of 1-6 MpaG, and a time of 0.1-3 h; and the conditions of the second step of the polymerization reaction include a temperature of 120-220°C, a pressure of 1-6 MpaG, and a time of 0.1-2 h.

35. The preparation method according to claim 34, characterized in that, The conditions of the first step of the polymerization reaction include a temperature of 80-120°C, a pressure of 1.5-5 MpaG, and a time of 0.5-2 h; and the conditions of the second step of the polymerization reaction include a temperature of 140-200°C, a pressure of 1.5-5 MpaG, and a time of 0.2-1 h.

36. The method of claim 1, wherein, The prepared functional polar polyolefin elastomer copolymer contains ethylene structural units, alpha-olefin structural units, structural unit A and structural unit B; wherein, the content of the ethylene structural units is 63-90 wt%, the content of the alpha-olefin structural units is 8-35 wt%, the content of the structural unit A is 0.1-2 wt%, and the content of the structural unit B is 0.05-2 wt%, based on the total weight of the polymer.

37. The method of claim 1, wherein, The polyolefin elastomer has a weight average molecular weight Mw of 40,000 to 120,000, a molecular weight distribution of less than 4, a density of 0.845 to 0.935 g / cm 3 , an organic solvent residual amount of 50 to 500 ppm, a melt index of 0.1 to 40 g / 10 min at 190°C under a load of 2.16 Kg, and a melting point of 40 to 110°C.

38. Use of a polyolefin elastomer produced according to the process of any one of claims 1 to 37, characterized in that, The polyolefin elastomer is applied in the fields of polymer modified material, polymer blended foaming material, polymer wire and cable material, polymer medical material, polymer solar power generation material or photovoltaic material.

39. The use according to claim 38, wherein The polyolefin elastomer is applied in the fields of photovoltaic power generation and photovoltaic adhesive film.

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