of polycarboxylic acid groups and containing at least 36 carbon atoms which are to be added in the form of their alkali metal salts to the binder dispersion in the commercially available dimer trimer fatty acids the ratio of c 36 dibasic dimer acid c 54 tribasic trimer acid and c 18 monobasic fatty acid varies from about 10 of the dimer acid to about 97 and from about 3 to about 90 of the trimer acid and from about 0 to about 10 of the monobasic acid the proportions of typical commercial materials given as percent of monobasic acid dimer acid and trimer acid are for example 0 97 3 10 87 3 1 95 4 0 87 13 0 83 17 0 75 25 0 20 80 0 10 90 0 40 60 the preferred polycarboxylic acids are those containing the dimer and trimer acid that is the dibasic c 36 and c 54 materials while improved results are obtained when the polybasic acid contains as little as about 20 c 36 acid it is preferred that the polybasic acid contain more than 50 c 36 c 54 dimer and or trimer acid and more preferably greater than about 80 weight percent in order to obtain a greater latitude in control of the canadian standard freeness in polymer latices in beater addition excellent results are obtained when the polybasic acids containing varying amounts of dimer and trimer acid used in conjunction with the defined alkali metal salts of 2 imidazoline derivatives defined in this invention with at least about 1 weight part each of these two components are used as the trimer dimer ratio is increased in a particular system usually the canadian.