A two-phase bead polymer having an average bead diameter of from 10.mu. to 150.mu. comprising(A) 88% to 99.5% by weight of a polymer of polymerized units of at least one methacrylic acid ester containing from 1 to 10 carbon atoms in the aliphatic, saturated alcohol component; and(B) 0.5% to 12% by weight of a polyurethane which has been obtained from (1) at least one dihydroxy compound, (2) a diisocyanate from the group comprising (a) aliphatic diisocyanates having a branched carbon skeleton of 7 to 26 carbon atoms, (b) cycloaliphatic diisocyanates and (c) aliphatic or cycloaliphatic diisocyanates modified by radical graft copolymerization with vinyl monomers, (3) an aliphatic or cycloaliphatic diamine and (4) a monofunctional chain terminator.