the present invention refers to a polymer latex made by free - radical polymerization comprising polymer particles containing structural units derived from at least one conjugated diene monomer and at least one aromatic vinyl monomer , whereby no vinyl pyridine is used in the polymerization and the polymer latex is polymerized in the presence of at least one chain transfer agent having the general formula rsh , wherein r is a linear alkyl group having 3 to 20 carbon atoms and the dried latex polymer has a mooney viscosity measured according to din 53 523 of 85 to 155 , as well as to articles made there from .