Free flowing powder composition, process for the preparation thereof and homogeneous layer derived therefrom.

摘要

A free flowing powder composition with a particle size of 800 mu m or less comprising: (a) 100 parts by weight of a block copolymer comprising at least one poly(monovinyl aromatic hydrocarbon) block and at least one hydrogenated or unhydrogenated poly(conjugated diene) block and having a monovinyl aromatic hydrocarbon content in the range of from 10 to 60% by weight based on total weight of block copolymer; (b) 50 to 200 parts by weight of plasticizing oil; (c) 50 to 200 parts by weight of a poly(monovinyl aromatic hydrocarbon) block compatible resin; and (d) 0.1 to 10% by weight based on total weight of composition of a dusting agent. Process for the preparation of the above free flowing powder composition, comprising first melt blending all components except the dusting agent and the blowing agent, if present, followed by cooling. The resulting composition is then pelletized or granulated and the granules or pellets thus obtained are cryogenically milled. Finally, the dusting agent and optionally the blowing agent are dry-blended with the powder resulting from the previous step. The free flowing powder composition is very useful for obtaining homogeneous layers having a smooth surface. These layers can be successfully be applied for carpet backings, conveyor belts, bottle cap sealants.