Process for preparing high-reactivity isobutene homo- or copolymers

A bulk- or solution polymerisation process for preparing a high-reactivity isobutene homo- or copolymer with a combined content of α-double bonds and β-double bonds per polyisobutene chain end of at least 60 mol %, the process comprising:

• polymerizing isobutene or an isobutene-comprising monomer mixture in the presence of a polymerization catalyst formed with at least one Lewis Acid and a donor, to obtain the high-reactivity isobutene homo- or copolymer, wherein the polymerization catalyst is selected from the group consisting of an aluminum trihalide-donor complex, an alkylaluminum halide-donor complex, an iron trihalide-donor complex, a gallium trihalide-donor complex, a titanium tetrahalide-donor complex, a zinc dihalide-donor complex, a tin dihalide-donor complex, a tin tetrahalide-donor complex, and a boron trihalide-donor complex,
• wherein the donor of said polymerization catalyst comprises a mixture of
• at least one organic compound (II) comprising at least one dihydrocarbyl ether of the general formula R8—O—R9, wherein R8 and R9 are each independently a C1- to C20-alkyl radical, a C1- to C20-haloalkyl radical, a C5- to C8-cycloalkyl radical, a C6- to C20-aryl radical, a C6- to C20-haloaryl radical, or a C7- to C20-arylalkyl radical, and
• at least one phosphorus-containing compound of formula (I)
• or
• P(OR1)(OR2)(OR3),or formula (Ia)
• P(OR1)(OR2)(OR3)(OR4)(OR5), formula (Ib)
• wherein
• X1, X2, and X3 independently of another are oxygen, sulphur, or a single bond, and
• R1, R2, R3, R4, and R5 independently of another are an organic residue with up to 20 carbon atoms,
• with the proviso that a complex formed from the at least one Lewis Acid and the at least one phosphorus-containing compound of formula (I), formula (Ia), or formula (Ib) has a melting point of not more than 60° C.,
• said at least one organic compound (II) and said at least one phosphorus-containing compound of formula (I), formula (Ia), or formula (Ib) are present in a molar ratio of 0.1:1 to 1:0.1, and
• said high-reactivity isobutene homo- or copolymer has a number-average molecular weight Mn, determined by gel permeation chromatography of 500 to 5,000 g/mol.