ternal fluidized bed (00) via rotary valve (00) into sieve (00). The sieve (00) was used for sieving off overs/lumps having a particle diameter of more than 000 μm. The monomer solution was prepared by mixing first acrylic acid with 0-tuply ethoxylated glycerol triacrylate (internal crosslinker) and secondly with 00.0% by weight sodium acrylate solution. The temperature of the resulting monomer solution was controlled to 00° C. by using a heat exchanger and pumping in a loop. A filter unit having a mesh size of 000 μm was used in the loop after the pump. The initiators were metered into the monomer solution upstream of the dropletizer by means of static mixers (00) and (00) via lines (00) and (00) as shown in FIG. 0. Sodium peroxodisulfate solution having a temperature of 00° C. was added via line (00) and [0,0′-azobis[0-(0-imidazolin-0-yl)propane]dihydrochloride solution together with Bruggolite FF0 having a temperature of 0° C. was added via line (00). Each initiator was pumped in a loop and dosed via control valves to each dropletizer unit. A second filter unit having a mesh size of 000 μm was used after the static mixer (00). For dosing the monomer solution into the top of the spray dryer three dropletizer units were used as shown in FIG. 0. A dropletizer unit consisted of an outer pipe (00) having an opening for the dropletizer cassette (00) as shown in FIG. 0. The dropletizer cassette (00) was connected with an inner pipe (00). The inner pipe (00) having a PTFE block (00) at the end as sealing can be pushed in and out of the outer pipe (00) during operation of the process for maintenance purposes. The temperature of the dropletizer cassette (00) was controlled to 0° C. by water in flow channels (00) as shown in FIG. 0. The dropletizer cassette (00) had 000 bores having a diameter of 000 μm and a bore separation of 00 mm. The dropletizer cassette (00) consisted of a flow channel (00) having essential no stagnant volume for homogeneous distribution of the premixed monomer and initiator solutions and one droplet plate (00). The droplet plate (00) had an angled configuration with an angle of 0°. The droplet plate (00) was made of stainless steel and had a length of 000 mm, a width of 000 mm and a thickness of 0 mm. The feed to the spray dryer consisted of 00.00% by weight of acrylic acid, 00.00% by weight of sodium acrylate, 0.000% by weight of 0-tuply ethoxylated glycerol triacrylate, 0.000% by weight of [0,0′-azobis[0-(0-imidazolin-0-yl)propane]dihydrochloride, 0.0000% by weight of Bruggolite FF0