Patent ID: 7750191

Claim:
A continuous process for producing a polyether alcohol having first and terminal polyalkylene oxide blocks, comprising: (1) continuously metering one or a mixture of H-functional starter substances, a first alkylene oxide or first mixture of alkylene oxides, and a DMC catalyst into a first reactor; (2) continuously reacting said one or mixture of H-functional starter substances and said first alkylene oxide or first mixture of alkylene oxides in the presence of said DMC catalyst in said first reactor to produce a polyether alcohol precursor with a first polyalkylene oxide block; (3) continuously withdrawing said polyether alcohol precursor from said first reactor; (4) continuously metering said precursor and a different alkylene oxide or a different mixture of alkylene oxides from that in the first reactor into a second reactor; (5) continuously reacting said precursor and said different alkylene oxide or a different mixture of alkylene oxides in said second reactor; and (6) continuously withdrawing polyether alcohol with first and terminal polyalkylene oxide blocks from the second reactor; wherein 50 to 98% of the total amount of alkylene oxide added to the first and second reactors is added to the first reactor and the polyether alcohol product having first and terminal polyalkylene oxide blocks produced has an hydroxyl number of 35 to 60 mgKOH/g and a content of primary alcohol groups of less than 12 mol % but not less than 3 mol %.