| 摘要 |
PURPOSE:To certainly purify the titled liquid waste from the washing finish of a printed board coated with washing finish photosensitive resin by relatively simplified operation without contaminating the water area for drainage, by heat treating said liquid waste in the presence of an alkali metal or Al salt to separately remove resinous components. CONSTITUTION:The liquid waste containing a water-soluble or -dispersible macromolecular compound having the group of CH2=CR-CO- (wherein R is H or CH2) in its molecule, a sensitizer, a thermopolymerization inhibitor, etc. is treated as follows: An alkali metal and/or Al salt is added to said liquid waste being slightly agitated, and the liquid waste is gradually heated up to a range of 30-80 deg.C. Hence, resinous components are gradually coagulated to form flocks with the rising of the temp. Then, the agitation is stopped, the liquid waste is coagulated, and the resinous components are separately removed by filtration or the like to separate the liquid waste of washing finish into the precipitated resinous components and a transparent supernatant liquid. Hereon, NaCl as said alkali metal salt or aluminum sulfate as said Al salt is added in an amount of 0.1-5wt% or 0.01-5wt%, respectively. |
