Agglomerating agents were synthesized in a latex form utilizing a seeded emulsion polymerization method to get high solid content NBR latex without exhibiting excessively high viscosity and unstability in the concentration process. An agglomerating agent synthesized with ethylacrylate in the core part and methacrylamide as the hydrophilic monomer in the shell effectively increased the average size of the NBR base latex when it was mixed with the NBR latex and settled for about 2 h. The NBR latex, treated with the proper amount of an agglomerating agent, could be concentrated up to 60.5 wt % solid, while an untreated NBR latex could only be concentrated to 45.0 wt % solid due to the viscosity buildup.