| abstract |
The invention relates to a process for the preparation of a copolymer in a semicontinuous operation in a polymerization apparatus comprising a polymerization reactor connected to a metering device, acid monomer being metered into the metering device and polyether macromonomer, acid monomer and water respectively in the polymerization reactor, acid monomer being metered from the metering device into the polymerization reactor , Before and / or introduced during the metering of the acid monomer in the polymerization radical polymerization initiator in the polymerization reactor, so that in the polymerization reactor, an aqueous medium is formed, in which acid monomer and polyether macromonomer are reacted to form the copolymer by free radical polymerization, the molar ratio of total used acid monomer to total used polyether macromonomer 20: 1 to 1: 1, that molar Verh ratio of acid monomer introduced into the polymerization reactor to the acid monomer metered into the polymerization reactor is 10: 1 to 1:10; and the acid monomer is metered with the proviso that at least 70 mole% of the total metered acid monomer is present at a constant or limited varying rate within be metered from 5 to 19 minutes. |