Ethylene/alpha-olefin copolymer and preparation method thereof

A method for preparing an ethylene/α-olefin copolymer, the method comprising:

• carrying out copolymerization reaction of ethylene and an α-olefin in solution in the presence of at least one catalyst in at least one reactor to obtain the ethylene/α-olefin copolymer;
• wherein, during the whole reaction process, the molar concentration ratio of ethylene to the α-olefin in the solution in the reactor is maintained between 0.6 and 2.2;
• the catalyst comprises:
• A. a catalyst component;
• B. an organoboron compound;
• and
• C. an organoaluminum compound;
• wherein the catalyst component is a premixture of a half-sandwich metallocene catalyst precursor and an alkyl aluminum compound;
• wherein the half-sandwich metallocene catalyst precursor comprises a compound having the general formula Cp′LMQ2, wherein,
• Cp′ is an optionally substituted cyclopentadiene group or a group derived therefrom, preferably one or more selected from the group consisting of substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl and substituted or unsubstituted fluorenyl;
• when Cp′ comprises a substituent, the substituent is one or more selected from the group consisting of C1-C12 alkyl, C1-C12 alkoxy, C1-C12 silyl, C6-C12 aryl, C7-C12 aralkyloxy, C2-C12 alkynyl and C8-C12 arylalkynyl, preferably one or more selected from the group consisting of C1-C8 alkyl, more preferably one or more selected from C1-C6 alkyl, and further preferably one or more selected from methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl;
• L is one or more of optionally substituted phenol ligands and phosphanimine ligands;
• M is an element selected from group IVB, preferably Zr and/or Ti, more preferably Ti;
• each Q is independently selected from halogen and/or C1-C6 alkyl, preferably halogen and/or C1-C3 alkyl, more preferably chlorine and/or methyl.