To obtain a modacrylic copolymer improved in flame resistance, processability into textiles, etc., by feeding a catalyst, acrylonitrile, and a hydrophilic group-containing comonomer into the lower section of a specified tubular reactor, feeding a halogenated comonomer into its lower section, and continuously polymerizing the monomers.
A tubular reactor equipped with an overflow and having a length/ diameter ratio of more than 1.8, and having a radially agitating means is used. 50-79 wt.% acrylonitrile, 1-5 wt.% comonomer containing hydrophilic groups, and 0.1-1 wt.%, based on the total monomer, catalyst of the type with a high decomposition rate decomposing at least 70 wt.%, under polymerization conditions, before reaching the feeding area of the halogenated comonomer are fed into the lower section of the reactor, and 20-48 wt.% halogenated monomer is fed into the upper section of the reactor. The monomers are continuously polymerized at a water/monomer ratio of 2.5-6.5 at a temp. of 35-50°C for 5-15 hr, and the reaction product is continuously taken out from the overflow at the top of the reaction. Unreacted monomers are removed in vacuo, the mixture is filtered, and the cake is washed with water and dried to obtain a modacrylic copolymer of a molecular weight of 10,000-1,000,000.
ANTONIO KUARUTA
RAFUAERE TEDESUKO
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