METHOD OF INHIBITING REVERSION OF DEGREE OF WHITENESS IN LIGNIN- CONTAINING MATERIALS; METHOD OF REDUCING REVERSION OF DEGREE OF WHITENESS OF BLEACHED CELLULOSES (VERSIONS); LIGNIN- CONTAINING ARTICLE RESISTANCE TO REVERSION OF DEGREE OF WHITENESS; PAPER, CELLULOSE, PAPER SHEET (VERSION); AND COMPOSITION FOR INHIBITING REVERSION OF DEGREE OF WHITENESS Russian patent published in 1998 - IPC

FIELD: pulp-and-paper industry. SUBSTANCE: all items of invention are designed for inhibiting reversion of degree of whiteness. Methods of invention provide for treatment of lignin materials (paper with pH 5.5-7.5 and lignin) with 2,5-dihydroxydioxane. In particular, treatment is effected for news-paper sheet. Lignin-cellulose product and paper based on lignin-cellulose material contain 2,5-dihydroxydioxane in amounts large enough to inhibit light reversion. Paper sheet contains cellulose treated with 2,5-dihydroxydioxane. Composition for inhibiting reversion of degree of whiteness includes aqueous mixture of calcium carbonate and 2,5-dihydroxydioxane. EFFECT: inhibited reversion of degree of whiteness. 29 cl, 4 tbl, 4 ex