Beta-alanine-N,N-di:acetic acid, alkali or ammonium salt complex former in paper mfr. - useful for biodegradable alkaline earth and heavy metal ion complexant in bleaching mechanical wood pulp and printed waste paper de inking

摘要

Beta-alanine-N,N-diacetic acid (I), alkali metal or ammonium salt, is used as complex former for alkaline earth and heavy metal ions in bleaching wood pulp, mfr. of paper, and deinking of printed waste paper. Prepn. comprises reacting iminodiacetic and acrylic acids in non basic aq. medium (EP 356 972). ADVANTAGE - Improved oxidative or reductive bleaching c.f. nitrilotriacetic acid (I) amt. of waterglass (stabiliser for H2O2) may be reduced, for min. deterioration in dewatering and deposition on paper and felt of paper machine, amt. of H2O2 in deinking may be reduced, and deposition of carbonates, silicates, and phosphates is min.. In an example, 100 g mechanical wood pulp suspension (pulp consistency 20 %, all pts. wt.) was mixed thoroughly with, (on dried wt.) wood pulp, 2 % waterglass, 0.75 % aq. NaOH, 1 % H2O2, and 0.06 % (I) as Na salt and kept at 50 deg. C for 2 hrs.. Paper (surface wt. 400 g/q. m) made from the bleached pulp had whiteness 67.6 % (deg. of remission, Elrepho photometer, wavelength 457 nm( 67.6 %. C.f. process was repeated except that (I) was replaced by (II) as Na sa whiteness of paper was 66.9%