| 摘要 |
<p>PURPOSE: To obtain a deinked pulp having high whiteness and a slight residual ink from waste paper as a raw material under saving a bleaching agent at a high yield. CONSTITUTION: In deinking of waste paper as a raw material, at least one kind of a nonionic surfactant selected from a product obtained by adding an alkylene oxide to a mixture of oil and fat with an alcohol or a group of compounds of the formula; RCOO(AO)m R' (R is a 7-23C alkyl or alkenyl; R' is H, a 1-22C alkyl or a 2-22C alkenyl or acyl; AO is a 2-4C oxyalkylene; (m) is an integer or >=1) is used for peeling off ink from the raw material waste paper. Ion concentrations of Ca and Al in a flotation system are kept respectively at 10-400ppm and 0-40ppm and pH is aadjusted at 4-9, and an amphoteric compound expressed by formulae I-V, etc., (R1 -R3 are each an alkyl or an alkenyl; R4 is an alkyl, an alkenyl or a hydroxyalkyl; M is H, an alkaline (earth) metal atom or ammonium, etc.) is added to the system in an amount of 0.01-1.0wt.% based on the waste paper, and treated.</p> |
