Pyridineimine nickel complex, preparation method and use thereof

Abstract

This invention provides a nickel complex of formula (I), wherein R 1 Selected from hydrogen, methyl, or phenylethyl, R 2 The radical is selected from hydrogen, phenylazo, p-tolueneazo, or p-fluorophenylazo, and X is selected from F, Cl, Br, or I. This nickel complex has a single catalytic active center and exhibits excellent catalytic activity when used as a catalyst for ethylene polymerization, yielding low molecular weight hyperbranched polyethylene with a narrow molecular weight distribution.

Description

Technical Field

[0001] This invention relates to the field of polyolefin catalysts, specifically to pyridineimine nickel complexes, their preparation methods, and their uses. Background Technology

[0002] At the end of the 20th century, Brookhart et al. made a landmark discovery: α-diimine Ni(II) complex catalysts for the efficient polymerization of olefins (J. Am. Chem. Soc., 1995, 117, 6414–6415), with the structural formula shown in Formula 1 below, opening up a new field of post-transition metal complex catalysis. In the past two decades, researchers in academia and industry have synthesized over a hundred Ni(II) complexes based on α-diimine ligands. Due to the diversity of ligand structures, the structure of the target polyethylene (e.g., polyethylene elastomers, branched polyethylene, low molecular weight polyethylene, and ultra-high molecular weight polyethylene) can be tuned by modifying the ligand skeleton and changing the type of aniline. This simple and effective control method has greatly enriched the applications of polyethylene (Coord. Chem. Rev., 2017, 350, 68-83).

[0003] In fact, the controllability of this polyethylene topology can be attributed to the unique "chain-walking" mechanism of nickel complexes during polymerization, especially the formation of hyperbranched polyethylene. The inventors discovered that the ligand structure has a significant impact on the catalytic behavior of nickel complexes (Dalton Trans., 2012, 41(39), 11999-12010). For example, R in the structure shown in Equation 2 below... 1 The group changes from methyl to isopropyl and R 2 When diphenylmethyl is used, its catalytic activity will gradually decrease from 9.54 × 10⁻⁶. 6 g(PE)mol -1 (Ni)h -1 Reduced to 7.32×10 6 g(PE)mol -1 (Ni)h -1 However, catalysts containing electron-withdrawing substituents exhibit higher activity, for example, when R in the structure shown in Equation 2 below... 2 =Chlorine and R 1 When α is diphenylmethyl, its catalytic activity is 10.2 × 10⁻⁶. 6 g(PE)mol -1 (Ni)h -1 Furthermore, the molecular weight of the resulting polyethylene is also directly affected by the substituents on the ligands. Specifically, ligands containing large-volume steric substituents generally tend to produce high molecular weight polyethylene, for example, when R in the structure shown in Equation 2 below... 1 = diphenylmethyl and R 2When chlorine is present, the molecular weight of the resulting polyethylene is 2.56 kg mol. -1 When R in the structure shown in Equation 2 is as follows 1 =Methyl and R 2 When methyl is used, the molecular weight of the resulting polyethylene is 1.73 kg mol. -1 Compared to the phenylimine nickel complex in Formula 2, the series of nickel complexes with naphthalene substituents shown in Formula 3 exhibit superior catalytic activity in the polymerization of ethylene. For example, when R in the structure shown in Formula 3 is... 1 =R 2 When α is diphenylmethyl, its catalytic activity is 12.0 × 10⁻⁶. 6 g(PE)mol -1 (Ni)h -1 (Dalton Trans., 2014, 43(8), 3339-3346). It is worth mentioning that the nickel complexes in Formula 1 and Formula 3 can efficiently catalyze the polymerization of ethylene to obtain highly branched polyethylene. The unique properties of this polymer, such as high branching degree, narrow polydispersity, and the potential for new elastomer polymers, have attracted great research interest from academia and industry.

[0004]

[0005] Therefore, in order to develop branched polyethylene products with superior performance, the study of the structure of ethylene polymer catalysts has become a key aspect of ethylene polymerization research. Further research is needed in this field to control the catalyst structure by manipulating the type of metal at the catalyst center, the metal valence state, and the structure of ligands, such as electronic and steric effects, thereby further improving the catalytic performance of these catalysts and the conditions and efficiency of their preparation methods. Summary of the Invention

[0006] In view of the technical problems existing in the prior art, this invention, based on the nickel complex structure shown in Formula 3 above, further considers electronic and steric effects to synthesize a series of naphthyl-substituted nickel complexes and conducts detailed polymerization studies. Simultaneously, it thoroughly considers the influence of catalyst structure factors and reaction conditions (such as reaction temperature, Al / Ni ratio, and reaction time) on the catalytic performance of the catalyst. The nickel complexes involved in this invention exhibit good catalytic activity for ethylene polymerization, and the steric and electronic effects of the substituent groups can effectively regulate the catalytic performance of the catalyst, yielding low molecular weight hyperbranched polyethylene products containing unsaturated groups.

[0007] One of the objectives of this invention is to provide a nickel complex as shown in formula (I):

[0008]

[0009] Among them, R1 Selected from hydrogen, methyl, or phenylethyl; R 2 It is selected from hydrogen, benzazo, p-tolueneazo or p-fluorobenzazo; X is selected from F, Cl, Br or I, preferably Cl or Br.

[0010] The nickel complex according to the present invention has the structure shown in formula (I-1), formula (I-2), formula (I-3), formula (I-4), formula (I-5) or formula (I-6):

[0011]

[0012] Another object of the present invention is to provide a method for preparing the nickel complex shown in formula (I) above, comprising the following steps:

[0013]

[0014]

[0015] The compound of formula (II) was mixed with a nickel-containing compound in a solvent and stirred to obtain the nickel complex shown in formula (I).

[0016] Among them, X and R 1 and R 2 As defined above.

[0017] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the nickel-containing compound is NiCl2·6H2O or NiBr2·DME, preferably NiCl2·6H2O.

[0018] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the molar ratio of the nickel-containing compound to the compound of formula (II) is 1:1 to 2, preferably 1:1 to 1.5, more preferably 1:1 to 1.2, for example 1:1, 1:1.04, 1:1.05, 1:1.1, 1:1.15, 1:1.2, and most preferably 1:1.05.

[0019] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the solvent used in the reaction is methanol, ethanol, isopropanol or acetonitrile, preferably ethanol.

[0020] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the molar volume ratio (mmol / mL) of the compound of formula (II) to the solvent is 1:8-1:12, preferably 1:9-1:11, more preferably 1:10-1:11, for example 1:10, 1:10.4, 1:10.5, 1:10.6, 1:10.8, 1:11.

[0021] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the reaction temperature is 10°C to 35°C, preferably 15°C to 30°C, and more preferably 20°C to 30°C.

[0022] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the reaction time is 18-30 h, preferably 22-26 h.

[0023] According to the method for preparing the nickel complex represented by formula (I) of the present invention, after the reaction is completed, the reaction solution is concentrated under reduced pressure to remove the solvent and obtain a residue. The residue is dissolved in a good solvent, and then a poor solvent is added for recrystallization to precipitate a solid. The solid is then filtered, washed, and dried to obtain the final product.

[0024] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the volume ratio of good solvent to poor solvent is 1:10-1:50, preferably 1:20-1:40, for example, 1:20, 1:25, 1:30, 1:35, 1:40.

[0025] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the good solvent is dichloromethane or tetrahydrofuran.

[0026] According to the method for preparing the nickel complex represented by formula (I) of the present invention, the undesirable solvent is diethyl ether.

[0027] According to the method for preparing the nickel complex of formula (I) of the present invention, the compound of formula (II) has the structure shown in formula (II-1), formula (II-2), formula (II-3), formula (II-4), formula (II-5) or formula (II-6):

[0028]

[0029] Another object of the present invention is to provide a catalyst composition comprising a main catalyst and an optional co-catalyst, wherein the main catalyst is a nickel complex as shown in formula (I) above.

[0030] According to the catalyst composition of the present invention, the co-catalyst is selected from one or more of aluminoxane, alkylaluminum and alkylaluminum chloride.

[0031] According to the catalyst composition of the present invention, wherein the aluminum oxane is methylaluminoxane (MAO) and / or triisobutylaluminum-modified methylaluminoxane (MMAO), the alkylaluminum is trimethylaluminum (AlMe3), and the alkylaluminum chloride is dimethylaluminum chloride (Me2AlCl); preferably, the co-catalyst is methylaluminoxane (MAO) and / or triisobutylaluminum-modified methylaluminoxane (MMAO).

[0032] According to the catalyst composition of the present invention, when the catalyst composition includes a co-catalyst, the molar ratio of metal Al in the co-catalyst to the central metal Ni of the nickel complex shown in formula (I) is (100-4000):1, preferably (400-2000):1, for example, 400:1, 1000:1, 1500:1 or 2000:1.

[0033] According to the catalyst composition of the present invention, when the co-catalyst is trimethylaluminum (AlMe3), the molar ratio of metallic Al in trimethylaluminum (AlMe3) to the central metallic Ni of the nickel complex shown in formula (I) is (100-1000):1, for example, 100:1, 200:1, 400:1, 500:1, 700:1, 800:1, 1000:1, preferably 400:1.

[0034] According to the catalyst composition of the present invention, when the co-catalyst is dimethylaluminum chloride (Me2AlCl), the molar ratio of metallic Al in dimethylaluminum chloride (Me2AlCl) to the central metallic Ni of the nickel complex shown in formula (I) is (100-1000):1, for example, 100:1, 200:1, 400:1, 500:1, 700:1, 800:1, 1000:1, preferably 500:1.

[0035] According to the catalyst composition of the present invention, when the co-catalyst is methylaluminoxane (MAO), the molar ratio of metal Al in methylaluminoxane (MAO) to the central metal Ni of the nickel complex shown in formula (I) is (1000-4000):1, preferably (1500-3500):1, for example, 1500:1, 2000:1, 2500:1, 3000:1, or 3500:1.

[0036] According to the catalyst composition of the present invention, when the co-catalyst is triisobutylaluminum-modified methylaluminoxane (MMAO), the molar ratio of metal Al in triisobutylaluminum-modified methylaluminoxane (MMAO) to the central metal Ni of the nickel complex shown in formula (I) is (1000-4000):1, preferably (1500-3000):1, for example, 1500:1, 1750:1, 2200:1, 2250:1, 2500:1.

[0037] Another object of the present invention is to provide a method for preparing hyperbranched polyethylene, comprising: carrying out an ethylene polymerization reaction under the action of the catalyst composition described above to obtain hyperbranched polyethylene.

[0038] According to the method for preparing hyperbranched polyethylene of the present invention, the polymerization reaction temperature is 20-60°C, preferably 20-50°C, for example, 20°C, 30°C, 40°C or 50°C.

[0039] According to the method for preparing hyperbranched polyethylene of the present invention, the polymerization reaction time is 5-120 min, preferably 5-80 min, for example, 5 min, 15 min, 30 min, 45 min or 60 min.

[0040] According to the method for preparing hyperbranched polyethylene of the present invention, the polymerization reaction pressure is 1-10 atm, preferably 5-10 atm, for example, 5 atm, 8 atm or 10 atm.

[0041] According to the method for preparing hyperbranched polyethylene of the present invention, the solvent used in the polymerization reaction is selected from one or more of toluene, dichloromethane, ethanol, tetrahydrofuran, n-hexane or cyclohexane, preferably toluene or n-hexane.

[0042] According to the method for preparing hyperbranched polyethylene of the present invention, the polymerization reaction is carried out in an ethylene atmosphere.

[0043] Another object of the present invention is to provide the use of the nickel complex shown in formula (I) above in the preparation of hyperbranched polyethylene.

[0044] Beneficial effects

[0045] This invention provides a class of naphthyl-containing pyridineimine nickel complexes. These nickel complexes have a single catalytic active center, and the molecular weight of the polymer can be controlled by changing the ligand structure and polymerization conditions. They also have the advantages of high catalytic activity, low cost, and stable performance.

[0046] This invention also provides a method for preparing such naphthyl-containing pyridineimine nickel complexes, which has the advantages of mild reaction conditions, short cycle and simple operation.

[0047] This invention also provides the use of such naphthyl-containing nickel complexes as catalysts for ethylene polymerization, exhibiting excellent catalytic activity to obtain low-molecular-weight branched polyethylene with a narrow molecular weight distribution. For example, the molecular weight distribution of the obtained branched polyethylene is mostly between 1.35 and 2.35; at 30°C, the activity of the nickel complex in catalyzing ethylene polymerization can reach as high as 13.14 × 10⁻⁶. 6 g·mol -1 (Ni)·h -1 The weight-average molecular weight (Mw) of the prepared polyethylene was between 807 and 3503 g·mol⁻¹. -1The catalyst exhibits strong control over the molecular weight of polyethylene; the melt temperature of the prepared polyethylene ranges from 45.6 to 85.2 °C. In summary, this type of catalyst can produce low-molecular-weight hyperbranched polyethylene materials with a wide range of applications, such as serving as a polymer blend compatibilizer substrate, a polymer processing aid (lubricating effect), and further modifying unsaturated groups to introduce polar groups, and even as a raw material for synthesizing functional macromolecular comonomers. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the crystal structure of the compound of formula (I-3) prepared in Example 3 of this application.

[0049] Figure 2 This is the high-temperature carbon NMR spectrum of the polymer obtained in Example 9a) of this application.

[0050] Figure 3 This is the high-temperature hydrogen NMR spectrum of the polymer obtained in Example 15d of this application.

[0051] Figure 4 The high-temperature carbon NMR spectrum of the polymer obtained in Example 15d) is shown. Detailed Implementation

[0052] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make improvements or modifications to the invention, and these equivalent forms also fall within the scope defined by this invention.

[0053] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0054] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0055] Unless otherwise specified, all concentrations in the following examples are molar concentrations.

[0056] The molecular weight and molecular weight distribution of the polymers obtained in the following ethylene polymerization examples were determined by conventional high-temperature GPC method, the melting point was determined by conventional DSC method, and the polymerization activity of the polymers was calculated by the following formula: Polymer activity = Polymer yield / (Catalyst dosage · Polymerization time).

[0057] All the synthesized complexes described below were confirmed by infrared and elemental analysis.

[0058] Example 1: Preparation of compound (I-1)

[0059] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-naphthylimine)ethyl)pyridine (0.12 g, 0.50 mmol) as shown in formula (II-1) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a green solid ([2-(1-(1-naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 65%.

[0060] The structural verification data is as follows:

[0061] FT-IR (cm) -1 ):1626(s),1596(s),1572(s),1509(m),1478(w),1441(m),1391(m),1372(s),1319(s),1265(s),112 9(m),1102(w),1080(m),1053(m),1021(m),977(m),876(m),813(m),780(s),767(s),748(s),674(s).

[0062] Elemental analysis: C 17 H 14 Theoretical values ​​for Cl2N2Ni (375.91): C, 54.32; H, 3.75; N, 7.45. Experimental values: C, 54.58; H, 4.01; N, 7.26.

[0063] Example 2 Preparation of compound (I-2)

[0064] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-(1-methyl)naphthylimine)ethyl)pyridine (0.13 g, 0.50 mmol) as shown in formula (II-2) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a yellow solid ([2-(1-(1-(1-methyl)naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 73%.

[0065] The structural verification data is as follows:

[0066] FT-IR (cm) -1):2988(m),2901(w),1623(s),1595(s),1570(s),1508(m),1478(w),1442(s),1372(s),1318(s),1259(s),1233(w),1185(w) ,1162(m),1130(m),1101(w),1078(s),1053(s),1024(s),977(m),920(m),870(m),812(m),780(s),767(s),746(s),671(s).

[0067] Elemental analysis: C 18 H 16 Theoretical values ​​for Cl2N2Ni (389.93): C, 55.44; H, 4.14; N, 7.18. Experimental values: C, 55.40; H, 4.33; N, 7.45.

[0068] Example 3 Preparation of compound (I-3)

[0069] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-(1-phenylethyl)naphthylimine)ethyl)pyridine (0.18 g, 0.48 mmol) as shown in formula (II-3) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a yellow solid ([2-(1-(1-(1-phenylethyl)naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 77%.

[0070] The structural verification data is as follows:

[0071] FT-IR (cm) -1 ):2970(m),1622(s),1596(s),1570(s),1508(m),1492(m),1443(s),1372(s),1316(s),1259(s),1162(m) ),1130(m),1052(s),1025(s),976(m),904(m),870(m),826(s),810(s),779(s),747(s),716(s),702(s).

[0072] Elemental analysis: C 25 H 22Cl2N2Ni(480.06): Theoretical values: C, 62.55; H, 4.62; N, 5.84. Experimental values: C, 62.40; H, 4.78; N, 6.06.

[0073] A schematic diagram of the crystal structure of compound (I-3) is shown below. Figure 1 As shown, for clarity, all hydrogen atoms in the complex molecule were not drawn when using the Oak Ridge Thermal Ellipsoid (ORTEP) diagram. Figure 1 As can be seen, the compound of formula (I-3) exhibits a trimer structure with chlorine atoms bridging each other (each nickel atom has an N,N-chelate ligand). The coordination geometry around each nickel atom can be described as a distorted octahedral configuration. For the central atoms Ni1 and Ni2, they are both coordinated with two N atoms (N1, N2, belonging to bidentate ligands) and connected with four chlorine atoms (Cl1, Cl2, Cl3, Cl4). The atoms coordinated with the central atom Ni3 are slightly different; nickel is coordinated with three chlorine atoms and one water molecule.

[0074] Example 4: Preparation of compound (I-4)

[0075] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-(4-phenylazo)naphthylimine)ethyl)pyridine (0.18 g, 0.48 mmol) of formula (II-4) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a yellow solid ([2-(1-(1-(4-phenylazo)naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 76%.

[0076] The structural verification data is as follows:

[0077] FT-IR (cm) -1 ):2971(m),1625(s),1597(s),1570(s),1508(m),1493(m),1442(s),1373(s),1317(s),1259 (s),1231(m),1162(m),1128(m),1051(s),1024(s),972(m),852(m),811(m),758(s),689(s).

[0078] Elemental analysis: C 23 H 18Cl2N4Ni(480.02): Theoretical values: C, 57.55; H, 3.78; N, 11.67. Experimental values: C, 57.42; H, 4.10; N, 11.51.

[0079] Example 5: Preparation of compound (I-5)

[0080] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-(4-(p-tolylazo))naphthylimine)ethyl)pyridine (0.18 g, 0.48 mmol) as shown in formula (II-5) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a yellow solid ([2-(1-(1-(4-(p-tolylazo))naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 81%.

[0081] The structural verification data is as follows:

[0082] FT-IR (cm) -1 ):2988(m),1627(s),1597(s),1570(s),1507(m),1442(m),1425(m),1388(s),1373(s),1316(s),1258(s),1231(s) ,1161(s),1126(m),1104(m),1051(s),1023(s),971(m),852(m),824(m),774(s),758(s),725(m),710(m),673(m).

[0083] Elemental analysis: C 24 H 20 Cl2N4Ni(494.05): Theoretical values: C, 55.47; H, 3.44; N, 11.25. Experimental values: C, 55.39; H, 3.64; N, 10.99.

[0084] Example 6: Preparation of compound (I-6)

[0085] At room temperature, NiCl2·6H2O (0.11 g, 0.48 mmol) and 2-(1-(1-(4-(p-fluoroazo))naphthylimine)ethyl)pyridine (0.18 g, 0.50 mmol) as shown in formula (II-6) were mixed and dissolved in 5 mL of ethanol and stirred for 24 h. After removing the solvent under reduced pressure, the reactants were dissolved in a small amount of dichloromethane and recrystallized with diethyl ether to precipitate a solid (the volume ratio of dichloromethane to diethyl ether was 1:25). The solid was filtered, washed with diethyl ether, and dried to obtain a yellow solid ([2-(1-(1-(4-(p-fluoroazo))naphthylimine)ethyl)pyridine]nickel chloride (II)), yield: 86%.

[0086] The structural verification data is as follows:

[0087] FT-IR (cm) -1 ):2988(m),2901(m),1629(s),1594(s),1572(s),1497(s),1442(m),1389(s),1374(s),1317(s),1259(s), 1229(s),1151(s),1136(m),1090(m),1057(s),1023(s),972(m),845(m),803(m),774(s),760(s),673(m).

[0088] Elemental analysis: C 23 H 17 Cl2FN4Ni(498.01): Theoretical values: C, 58.35; H, 4.08; N, 11.34. Experimental values: C, 58.68; H, 4.32; N, 11.36.

[0089] Example 7: Ethylene polymerization reaction under pressure using compound (II) and Me2AlCl co-catalyst.

[0090] Under an ethylene atmosphere, 20 mL of toluene, 30 mL of a toluene solution containing 2 μmol of the main catalyst (II) compound, 1.0 mL of the co-catalyst Me₂AlCl (1.0 mol / L toluene solution), and 50 mL of toluene were sequentially added to a 250 mL stainless steel autoclave. At this point, the Al / Ni molar ratio was 500:1. Mechanical stirring was initiated and maintained at 400 rpm. When the polymerization temperature reached 30°C, ethylene was introduced into the reactor, and the polymerization reaction began. The ethylene pressure was maintained at 10 atm at 30°C, and stirring was continued for 30 min. The reaction solution was neutralized with an ethanol solution acidified with 5% hydrochloric acid to obtain a polymer precipitate. The precipitate was washed several times with ethanol, vacuum dried to constant weight, and weighed.

[0091] Polymerization activity: 2.11 × 10⁻⁶ 6 g·mol-1 (Ni)·h -1 Polymer T m =84.4℃. (T) m (The melting temperature of the polymer is obtained by DSC testing), and the polymer molecular weight M is... w =1231g·mol -1 PDI = 1.64 (M w (This represents the weight-average molecular weight of the polymer, obtained through heated GPC testing).

[0092] Example 8: Ethylene polymerization reaction under pressure using compound (II) and AlMe3 co-catalyst.

[0093] Under an ethylene atmosphere, 20 mL of toluene, 30 mL of a toluene solution containing 2 μmol of the main catalyst (II) compound, 0.8 mL of the co-catalyst AlMe3 (1.0 mol / L toluene solution), and 50 mL of toluene were sequentially added to a 250 mL stainless steel autoclave. At this point, the Al / Ni molar ratio was 400:1. Mechanical stirring was initiated and maintained at 400 rpm. When the polymerization temperature reached 30°C, ethylene was introduced into the reactor, and the polymerization reaction began. The ethylene pressure was maintained at 10 atm at 30°C, and stirring was continued for 30 min. The reaction solution was neutralized with an ethanol solution acidified with 5% hydrochloric acid to obtain a polymer precipitate. The precipitate was washed several times with ethanol, vacuum dried to constant weight, and weighed.

[0094] Polymerization activity: 2.76 × 10 6 g·mol -1 (Ni)·h -1 Polymer T m =67.6℃. (T) m (The melting temperature of the polymer is obtained by DSC testing), and the polymer molecular weight M is... w =1126 g·mol -1 PDI = 1.88 (M w (This represents the weight-average molecular weight of the polymer, obtained through heated GPC testing).

[0095] Example 9: Ethylene polymerization reaction under pressure using compound (II) and MAO co-catalyst.

[0096] a) Under an ethylene atmosphere, 20 mL of toluene, 30 mL of a toluene solution containing 2 μmol of the main catalyst (II) compound, 2.7 mL of the co-catalyst MAO (1.46 mol / L toluene solution), and 50 mL of toluene were sequentially added to a 250 mL stainless steel autoclave. At this point, the Al / Ni molar ratio was 2000:1. Mechanical stirring was initiated and maintained at 400 rpm. When the polymerization temperature reached 30°C, ethylene was introduced into the reactor, and the polymerization reaction began. The ethylene pressure was maintained at 10 atm at 30°C, and stirring was continued for 30 min. The reaction solution was neutralized with an ethanol solution acidified with 5% hydrochloric acid to obtain a polymer precipitate. The precipitate was washed several times with ethanol, dried under vacuum to constant weight, and weighed.

[0097] Polymerization activity: 7.18 × 10 6 g·mol -1 (Ni)·h -1 Polymer T m =51.7℃. (T) m (The melting temperature of the polymer is obtained by DSC testing), and the polymer molecular weight M is... w =1518g·mol -1 PDI = 1.82 (M w (This represents the weight-average molecular weight of the polymer, obtained through heated GPC testing).

[0098] Take 100 mg of the obtained polymer, dissolve it in 5 mL of deuterated tetrachloroethane, and test the polymer at 30 °C. 13 C data. Signal accumulation of 2000 times yielded peak shifts between 10-40 ppm, indicating shifts in hydrogen atoms in double bonds, the main chain, and branches. This confirms that the obtained polymer is unsaturated branched polyethylene (branching degree: 69 / 1000C). See the detailed spectrum below. Figure 2 Among them, the two characteristic peaks with chemical shifts of 12.95 and 19.61 ppm in the carbon spectrum data indicate the presence of sec-butyl branches in the polymer, indicating that the polymer is hyperbranched polyethylene.

[0099] b) is basically the same as a), except that the amount of co-catalyst used is 2.1 mL of MAO (1.46 mol / L toluene solution), making the Al / Ni molar ratio 1500:1. Polymerization activity: 5.30 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =54.3℃, M w =1537g·mol -1 PDI = 1.96.

[0100] c) is basically the same as a), except that the amount of co-catalyst used is 2.4 mL of MAO (1.46 mol / L toluene solution), making the Al / Ni molar ratio 1750:1. Polymerization activity: 7.18 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =51.7℃, M w =1518g·mol -1 PDI = 1.82.

[0101] d) is basically the same as a), except that the amount of co-catalyst used is 3.1 mL of MAO (1.46 mol / L toluene solution), making the Al / Ni molar ratio 2250:1. Polymerization activity: 5.72 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =67.2℃, M w =1841g·mol -1 PDI = 2.25.

[0102] e) is basically the same as a), except that: the amount of co-catalyst used is 3.4 mL of MAO (1.46 mol / L toluene solution), making the Al / Ni molar ratio 2500:1. Polymerization activity: 5.11 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =61.6℃, M w =1873g·mol -1 PDI = 1.75.

[0103] f) is basically the same as a), except that the polymerization temperature is 20℃. Polymerization activity: 0.40×10 6 g·mol -1 (Ni)·h -1 Polymer T m =68.6℃, M w =2858g·mol -1 PDI = 2.17.

[0104] g) is basically the same as a), except that the polymerization temperature is 40℃. Polymerization activity: 5.25 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =51.7℃, M w =1202g·mol-1 PDI = 1.69.

[0105] h) is basically the same as a), except that the polymerization time is 5 min. Polymerization activity: 5.76 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =62.2℃, M w =1476 g·mol -1 PDI = 1.95.

[0106] i) Basically the same as a), except that the polymerization time is 15 min. Polymerization activity: 13.14 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =52.7℃, M w =1510 g·mol -1 PDI = 1.94.

[0107] j) is basically the same as a), except that the polymerization time is 45 min. Polymerization activity: 6.27 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =54.5℃, M w =1536g·mol -1 PDI = 2.06.

[0108] k) is basically the same as a), except that the polymerization time is 60 min. Polymerization activity: 7.85 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =55.4℃, M w =1618 g·mol -1 PDI = 1.67.

[0109] l) is basically the same as a), the difference being: polymerization pressure 5 atm. Polymerization activity: 3.90 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =30.1℃, M w =1052g·mol -1 PDI = 1.74.

[0110] Example 10: Ethylene polymerization reaction under pressure using compound of formula (I) and MAO co-catalyst.

[0111] Basically the same as Example 9a), except that the main catalyst is compound (I). Polymerization activity: 3.11 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =56.4℃, M w =871g·mol -1 PDI = 1.63.

[0112] Example 11: Ethylene polymerization reaction under pressure using compound (III) and MAO co-catalyst.

[0113] Basically the same as Example 9a), except that the main catalyst is a compound of formula (III). Polymerization activity: 10.1 × 10 6 g·mol -1 (Ni)·h -1 Polymer T m =54.5℃, M w =2923g·mol -1 PDI = 2.25.

[0114] Example 12: Ethylene polymerization reaction under pressure using compound (IV) and MAO co-catalyst.

[0115] Basically the same as Example 9a), except that the main catalyst is a compound of formula (IV). Polymerization activity: 2.01 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =66.2℃, M w = 913 g·mol -1 PDI = 1.35.

[0116] Example 13: Ethylene polymerization reaction under pressure using compound (V) and MAO co-catalyst.

[0117] Basically the same as Example 9a), except that the main catalyst is compound (V). Polymerization activity: 5.08 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =55.1℃, M w =1102 g·mol -1 PDI = 1.79.

[0118] Example 14: Ethylene polymerization reaction under pressure using compound (VI) and MAO co-catalyst.

[0119] Basically the same as Example 9a), except that the main catalyst is a compound of formula (VI). Polymerization activity: 4.95 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =56.7℃, M w =1000g·mol -1 PDI = 1.66.

[0120] Example 15: Ethylene polymerization reaction under pressure using compound (II) and MMAO co-catalyst.

[0121] a) Under an ethylene atmosphere, 20 mL of toluene, 30 mL of a toluene solution of compound (II) (2 μmol), 2.1 mL of the co-catalyst MMAO (1.93 mol / L toluene solution), and 50 mL of toluene were sequentially added to a 250 mL stainless steel autoclave. At this point, the Al / Ni molar ratio was 2000:1. Mechanical stirring was initiated and maintained at 400 rpm. When the polymerization temperature reached 30°C, ethylene was introduced into the reactor, and the polymerization reaction began. The ethylene pressure was maintained at 10 atm at 30°C, and stirring was continued for 30 min. The reaction solution was neutralized with an ethanol solution acidified with 5% hydrochloric acid to obtain a polymer precipitate. The precipitate was washed several times with ethanol, vacuum dried to constant weight, and weighed.

[0122] Polymerization activity: 4.21 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =61.1℃. (T m (The melting temperature of the polymer is obtained by DSC testing), and the polymer molecular weight M is... w =1122g·mol -1 PDI = 1.69 (M w (This represents the weight-average molecular weight of the polymer, obtained through heated GPC testing).

[0123] b) is basically the same as a), except that the co-catalyst used is 1.6 mL of MMAO (1.93 mol / L toluene solution), making the Al / Ni molar ratio 1500:1. Polymerization activity: 3.95 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =64.8℃, M w =1795g·mol -1 PDI = 1.74.

[0124] c) is basically the same as a), except that the amount of co-catalyst used is 2.6 mL of MMAO (1.93 mol / L toluene solution), making the Al / Ni molar ratio 2500:1. Polymerization activity: 5.94 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =64.3℃, M w =1933g·mol -1 PDI = 1.96.

[0125] d) is basically the same as a), except that the amount of co-catalyst used is 3.1 mL of MMAO (1.93 mol / L toluene solution), making the Al / Ni molar ratio 3000:1. Polymerization activity: 6.73 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =57.9℃, M w =1638g·mol -1 PDI = 1.83.

[0126] Take 100 mg of the obtained polymer, dissolve it in 5 mL of deuterated tetrachloroethane, and test the polymer at 30 °C. 1 H and 13 C data. Signal accumulation at 64 and 2000 times yielded peak shifts between 0-6 and 10-40 ppm, respectively, indicating shifts in hydrogen atoms on double bonds, the main chain, and branches. This confirms that the obtained polymer is unsaturated branched polyethylene (branching degree: 62 / 1000C). See the detailed spectrum below. Figure 3 and Figure 4 Among them, the two characteristic peaks with chemical shifts of 12.91 and 19.58 ppm in the carbon spectrum data indicate the presence of sec-butyl branches in the polymer, indicating that the polymer is hyperbranched polyethylene.

[0127] e) is basically the same as a), except that the amount of co-catalyst used is 3.6 mL of MMAO (1.93 mol / L toluene solution), making the Al / Ni molar ratio 3500:1. Polymerization activity: 5.68 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =63.1℃, M w =1369 g·mol -1 PDI = 1.95.

[0128] f) is basically the same as d), except that the polymerization temperature is 20℃. Polymerization activity: 5.16×10 6 g·mol -1 (Ni)·h -1 Polymer T m =81.4℃, M w =3208g·mol -1 PDI = 2.35.

[0129] g) is basically the same as d), except that the polymerization temperature is 40℃. Polymerization activity: 3.53×10 6 g·mol -1 (Ni)·h -1 Polymer T m =45.6℃, M w =1233g·mol -1 PDI = 1.52.

[0130] h) is basically the same as d), except that the polymerization temperature is 50℃. Polymerization activity: 0.94×10 6 g·mol -1 (Ni)·h -1 Polymer T m =51.6℃, M w =1076 g·mol -1 PDI = 1.55.

[0131] i) Basically the same as d), the difference being: polymerization time 5 min. Polymerization activity: 6.78 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =62.2℃, M w =1524 g·mol -1 PDI = 1.58.

[0132] j) is basically the same as d), except that the polymerization time is 15 min. Polymerization activity: 4.31 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =57.4℃, M w =1578g·mol -1 PDI = 1.75.

[0133] k) is basically the same as d), the difference being: polymerization time is 45 min. Polymerization activity: 6.02 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer Tm =66.0℃, M w =1746 g·mol -1 PDI = 1.84.

[0134] l) is basically the same as d), the difference being: polymerization time is 60 min. Polymerization activity: 5.55 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =68.6℃, M w =1837g·mol -1 PDI = 1.82.

[0135] m) is basically the same as d), the difference being: polymerization pressure 5 atm. Polymerization activity: 1.82 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =67.0℃, M w =1253g·mol -1 PDI = 1.68.

[0136] Example 16: Ethylene polymerization reaction under pressure using compound (I) and MMAO co-catalyst.

[0137] Basically the same as Example 15d), except that the main catalyst is compound (I). Polymerization activity: 1.85 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =62.8℃, M w =841g·mol -1 PDI = 1.85.

[0138] Example 17: Ethylene polymerization reaction under pressure using compound (III) and MMAO co-catalyst.

[0139] Basically the same as Example 15d), except that the main catalyst is compound (III). Polymerization activity: 6.50 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =85.2℃, M w =3503 g·mol -1 PDI = 2.29.

[0140] Example 18: Ethylene polymerization reaction under pressure using compound (IV) and MMAO co-catalyst.

[0141] Basically the same as Example 15d), except that the main catalyst is a compound of formula (IV). Polymerization activity: 2.99 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =56.4℃, M w = 807 g·mol -1 PDI = 1.58.

[0142] Example 19: Ethylene polymerization reaction under pressure using compound (V) and MMAO co-catalyst.

[0143] Basically the same as Example 15d), except that the main catalyst is compound (V). Polymerization activity: 5.31 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =54.9℃, M w =840g·mol -1 PDI = 1.62.

[0144] Example 20: Ethylene polymerization reaction under pressure using compound (VI) and MMAO co-catalyst.

[0145] Basically the same as Example 15d), except that the main catalyst is a compound of formula (VI). Polymerization activity: 3.49 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =57.9℃, M w =842 g·mol -1 PDI = 1.59.

[0146] Example 21: Ethylene polymerization reaction under pressure using compound (II) and MMAO co-catalyst.

[0147] Basically the same as Example 15d), except that the solvent was n-hexane. Polymerization activity: 3.52 × 10⁻⁶ 6 g·mol -1 (Ni)·h -1 Polymer T m =73.5℃. (T) m (The melting temperature of the polymer is obtained by DSC testing), and the polymer molecular weight M is... w =3352g·mol -1 PDI = 1.71 (M w (This represents the weight-average molecular weight of the polymer, obtained through heated GPC testing).

[0148] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A nickel complex as shown in formula (I): in, R 1 Selected from hydrogen, R 2 Selected from phenylazo, p-tolueneazo, or p-fluorophenylazo; or, R 1 Selected from methyl or phenylethyl; R 2 Selected from hydrogen; X is selected from F, Cl, or I.

2. The nickel complex according to claim 1, having the structure shown in formula (I-2), formula (I-3), formula (I-4), formula (I-5), or formula (I-6):

3. A method for preparing the nickel complex as described in claim 1 or 2, comprising the following steps: The compound of formula (II) was mixed with a nickel-containing compound in a solvent and stirred to obtain the nickel complex shown in formula (I). in, X, R 1 and R 2 As defined in claim 1.

4. The preparation method according to claim 3, wherein, The nickel-containing compound is NiCl2·6H2O; the solvent used in the reaction is methanol, ethanol, isopropanol or acetonitrile.

5. The preparation method according to claim 3 or 4, wherein, The molar ratio of the nickel-containing compound to the compound of formula (II) is 1:1 to 2; the molar volume ratio of the compound of formula (II) to the solvent is 1:8 to 1:

12.

6. The preparation method according to claim 5, wherein, The molar ratio of the nickel-containing compound to the compound of formula (II) is 1:1 to 1.5; the molar volume ratio of the compound of formula (II) to the solvent is 1:9 to 1:

11.

7. The preparation method according to claim 3 or 4, wherein, The reaction temperature is 10℃ to 35℃; the reaction time is 18-30h.

8. The preparation method according to claim 7, wherein, The reaction temperature is 15℃ to 30℃; the reaction time is 22-26h.

9. The preparation method according to claim 7, wherein, The reaction temperature is 20℃ to 30℃.

10. The preparation method according to claim 3 or 4, wherein, After the reaction is complete, the reaction solution is concentrated under reduced pressure to remove the solvent and obtain the residue. The residue is dissolved in a good solvent, and then a poor solvent is added for recrystallization to precipitate the solid. The solid is then filtered, washed, and dried to obtain the final product.

11. The preparation method according to claim 10, wherein, The volume ratio of good solvent to poor solvent is 1:10-1:

50.

12. The preparation method according to claim 11, wherein, The volume ratio of good solvent to poor solvent is 1:20-1:

40.

13. The preparation method according to claim 10, wherein, The good solvent is dichloromethane or tetrahydrofuran; the bad solvent is diethyl ether.

14. A catalyst composition comprising a main catalyst and optionally a co-catalyst, wherein, The main catalyst is the nickel complex as described in claim 1 or 2.

15. The catalyst composition according to claim 14, wherein, The cocatalyst is selected from one or more of aluminoxane, alkylaluminum, and alkylaluminum chloride.

16. The catalyst composition according to claim 15, wherein, The aluminum oxane is methylaluminoxane and / or triisobutylaluminum-modified methylaluminoxane, the alkylaluminum is trimethylaluminum, and the alkylaluminum chloride is dimethylaluminum chloride.

17. The catalyst composition according to claim 15, wherein, The cocatalyst is methylaluminoxane and / or triisobutylaluminum modified methylaluminoxane.

18. The catalyst composition according to any one of claims 15-17, wherein, When the catalyst composition includes a co-catalyst, the molar ratio of metallic Al in the co-catalyst to the central metallic Ni of the nickel complex shown in formula (I) is (100-4000):

1.

19. The catalyst composition according to claim 18, wherein, When the catalyst composition includes a co-catalyst, the molar ratio of metallic Al in the co-catalyst to the central metallic Ni of the nickel complex shown in formula (I) is (400-2000):

1.

20. The catalyst composition according to claim 15 or 16, wherein, When the cocatalyst is trimethylaluminum, the molar ratio of metallic Al in trimethylaluminum to the central metallic Ni of the nickel complex shown in formula (I) is (100-1000):

1.

21. The catalyst composition according to claim 15 or 16, wherein, When the cocatalyst is dimethylaluminum chloride, the molar ratio of metallic Al in dimethylaluminum chloride to the central metallic Ni of the nickel complex shown in formula (I) is (100-1000):

1.

22. The catalyst composition according to claim 15 or 16, wherein, When the cocatalyst is methylaluminoxane, the molar ratio of metal Al in methylaluminoxane to the central metal Ni of the nickel complex shown in formula (I) is (1000-4000):

1.

23. The catalyst composition according to claim 15 or 16, wherein, When the cocatalyst is triisobutylaluminum-modified methylaluminoxane, the molar ratio of metal Al in the triisobutylaluminum-modified methylaluminoxane to the central metal Ni of the nickel complex shown in formula (I) is (1000-4000):

1.

24. A method for preparing hyperbranched polyethylene, comprising: Under the action of the catalyst composition as described in any one of claims 14-23, ethylene polymerization is carried out to obtain hyperbranched polyethylene.

25. The preparation method according to claim 24, wherein, The polymerization temperature is 20-60℃; the polymerization time is 5-120 min; and the polymerization pressure is 1-10 atm.

26. The preparation method according to claim 25, wherein, The polymerization temperature is 20-50℃; the polymerization time is 5-80 min; and the polymerization pressure is 5-10 atm.

27. The preparation method according to any one of claims 24-26, wherein, The solvent used in the polymerization reaction is selected from one or more of toluene, dichloromethane, ethanol, tetrahydrofuran, n-hexane, or cyclohexane.

28. The preparation method according to claim 27, wherein, The solvent used in the polymerization reaction is selected from toluene or n-hexane.

29. Use of the nickel complex as described in claim 1 or 2 in the preparation of hyperbranched polyethylene.

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