| 摘要 |
<p>In a process for the polymerization of an oxirane with a catalyst formed by reacting an organoaluminium compound with a chelating agent or with water and a chelating in an amount such that the molar ratio of chelating agent to aluminium compound is 0.01 to 1.5 and the molar ratio of water, when used, to aluminium compound is 0.1 to 1.5, a carbonium ion precursor, i.e. a compound which on reaction with one or more of the components of the reaction mixture will form a carbonium ion, is added as a molecular weight control agent in an amount such that the molar ratio of the precursor to the organoaluminium compound is at least 0.01. Carbonium ion precursors, of which many are specified, include carboxylic and sulphonic acid anhydrides and halides, phosgene, organic compounds which can yield a carbonium ion conjugated with a potential resonating system such as allylic halides (e.g. allyl and crotyl halides) and phenylated methyl halides, nitrates or sulphates (e.g. benzyl and triphenylmethyl compounds), acetals, thioethers, polysulphides, organoboron compounds, sulphuryl halides, phosphorus halides, a -haloalkyl ethers and nitrosyl chloride. Suitable organoaluminium compounds include the trialkyls, tricycloalkyls, triaryls, alkyl hydrides, halides, alkoxides and aroxides and their complexes, e.g. with alkali metals or tetrahydrofuran. The preferred chelating agents contain an -OH or -SH group (e.g. . hydroxy, enol of a ketone, sulphoxide or sulphone or OH of a carboxyl (group) and a further group which contains an oxygen, nitrogen or sulphur atom that forms a co-ordinate band with the aluminium. Many examples are given including diketones, ketoacids, ketoesters, ketoaldehydes, hydroxyketones, hydroxyaldehydes, hydroxyesters, dicarboxylic acids and their esters, dialdehydes, alkoxyacids, ketoximes, dialdehyde monoximes, hydroxamic acids, dioximes, nitroalcohols, nitroketones, 2-nitroacetic acid, nitroso-oximes, 2,5-dihydroxy-p-benzoquinone, bis (1,3 - diketones) and bis (1,2 - dioximes). Polymerization may be effected in bulk or in solution. Many suitable epoxides are specified including alkylene oxides, halo-substituted alkylene oxides, cycloaliphatic mono- and dioxides, epoxy ethers, glycidyl esters, alkyl glycidates, styrene oxides, diene mono- and dioxides, epoxystearates and epoxy amino and ammonium compounds. In examples polymers are prepared from: propylene oxide/allyl glycidyl ether; propylene oxide; epichlorhydrin/allyl glycidyl ether/ethylene oxide; epichlorhydrin/ethylene oxide; and epichlorhydrin. Propylene oxide/allyl glycidyl ether copolymers are vulcanized using a conventional sulphur formulation.</p> |
