Particulate vinyl polymer

PURPOSE:To obtain a granular vinyl polymer for use in a water-based coating compsn. excellent in workability, pigment-dispersing properties and water resistance. CONSTITUTION:A granular vinyl polymer having an acid value of 30 to 150mg KOH/g and comprising at least 95wt.% particles satisfying the following relationship: 1<=b/a<=1.5 [wherein (a) is the minor axis diameter of each particle, and (b) is the major axis diameter thereof] and having a minor axis diameter (a) as well as major axis diameter (b) of 30 to 400mum.