| 摘要 |
<p>Recovery of a plastic material found in large amts. in waste plastic material such as used plastic bottles comprises grinding the waste sepg. the waste from any paper rot adhering to the waste material; removing the paper adhering to the waste material by stirring the material in an aq. soln. of alkali and recovering the plastic by successive elutriation in liq. medium. The density of the aq. alkali is adjusted so that it can be used in the first eluctriation operation. Used for the economic and simplified recovery of rigid p.v.c., which can be re-used, from waste material contg. rigid p.v.c., polyethylene, polypropylene, polystyrene, glass, metal, bakelite resins, aminoplastics, etc. The process may also be used for bulk recovery of other plastics, e.g. acrylic polymers. As aq. alkali, NaOH is pref. although Na2CO3 soln. is also suitable. The alkali is used at a concn. of 5-50 g/l soln., at 50-70 degrees C. Density adjustment is made by adding the water sol. NaCl, e.g. for rigid p.v.c. the density required is 1.08-1.3, whilst for acrylic polymers, the density required is 1.1-1.4.</p> |
