A method for preparing tapered block copolymers which are particularly
useful for blend components in blends with polymers of styrene. In the
first embodiment of this invention the copolymers are prepared in a
polymerization process by sequentially charging: (1) an initiator and
monovinylaromatic monomers in the presence of a randomizer; (2) an
initiator and monovinylaromatic monomers; (3) a mixture of
monovinylaromatic and conjugated diene monomers; and (4) a coupling agent;
to produce a polymodal tapered block copolymer. In a second embodiment of
the invention tapered block copolymers are prepared in a polymerization
process by sequentially charging: (1) an initiator and monovinylaromatic
monomers in the presence of a randomizer; (2) an initiator and
monovinylaromatic monomers; (3) a mixture of monovinylaromatic and
conjugated diene monomers; (4) a mixture of monovinylaromatic and
conjugated diene monomers; and (5) a coupling agent; to produce a
polymodal tapered block copolymer. The invention copolymers and blends of
the invention copolymers with polymers of styrene are particularly useful
for applications such as packaging and food or drink containers which
require transparency, low blueness, colorlessness, good impact strength
and ductility.