Patent ID: 6251220
Filing Date: 2001-06-26
Classification: D21C,Y02W

Abstract:
A deinking method comprising the following steps:(1) a first step wherein ink is liberated from waste paper as a raw material in the presence of at least one non-ionic surfactant under alkaline conditions, wherein said non-ionic surfactant is a reaction product obtained by adding an alkylene oxide to a mixture of oil and fat and an alcohol;(2) a second step wherein the ink liberated in the first step is removed in a flotation system and prevented from re-adhering to the waste paper as raw material, said second step comprising at least one step, which is carried out in the presence of at least one member selected from the group consisting of amines and acid salts of amines in an amount of from 0.01 to 1.0% by weight based on the weight of the wastepaper, wherein the pH is lower in comparison to the pH of the first step and is in the range of 4 to 9; andwherein the amines and acid salts of amines are selected from the group consisting of compounds represented by the formulas (a.sub.2) to (h.sub.2) and polymers represented by the formulas (i.sub.2) to (l.sub.2), each of which has an amino-nitrogen content of 0.01 to 35% by weight and a weight-average molecular weight of 2,000 to 3,000,000: ##STR34##in formulas (a.sub.2) to (h.sub.2), R.sub.1 represents an alkyl, alkenyl or .beta.-hydroxyalkyl group having 8 to 36 carbon atoms; R.sub.2 and R.sub.3 may be the same or different from each other and each represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms; HA represents an inorganic or organic acid; AO represents an oxyalkylene group having 2 to 4 carbon atoms; 1 and m are each zero or a positive integer with the proviso that 1 plus m is an integer of 1 to 300; and W.sub.1, W.sub.2, W.sub.3 and W.sub.4 may be the same or different from one another and each represents a hydrogen atom or an alkyl group having 1 to 24 carbon atoms; ##STR35##in formulas (i.sub.2) to (l.sub.2), R.sub.1 represents an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms; R.sub.2, R.sub.3 and R.sub.6 may be the same or different from one another and each represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms; R.sub.4 and R.sub.5 may be the same or different from each other and each represents a hydrogen atom or a methyl group; HA represents an inorganic or organic acid; Y represents 0 or NH; p represents an integer of 1 to 10; and l, m and n are each such a positive number that the weight-average molecular weight of the polymer would be a value in the range of from 2,000 to 3,000,000.