ADDITIVE COMPRISING CELLULOSE DERIVATIVES HAVING GEL-LIKE FLOWABILITY USEFUL IN COMPRESSION MOLDING OF BUILDING MATERIAL TO PROVIDE WATER RETENTION ABILITY AT HIGH TEMPERATURE, AND TO IMPROVE SURFACE QUALITY AND SHAPE STABILITY OF COMPRESSED PRODUCT

摘要

PURPOSE: An additive comprising cellulose derivatives having gel-like flowability which can be suitably used in compression molding of a building material such as cement, is provided to give good water retention ability at high temperature, to reduce the pressure during compression molding, to improve discharge velocity at a discharging hole, surface quality and shape stability of the compressed product. CONSTITUTION: The additive suitably used in compression molding of a building material comprises irreversibly crosslinked cellulose ether which has gel-like flowability. The additive is produced by: carrying out alkalization of cellulose with an aqueous solution of alkali metal hydroxides in the presence of a suspending medium; reacting the alkalized cellulose with at least one alkylene oxides; reacting the alkalized cellulose with alkyl halides present in a suspending medium; subsequently or at the same time, reacting the alkalized cellulose with 0.0001-0.05 equivalent weight of a crosslinking agent; and optionally adding alkali metal hydroxides and/or an alkylating agent thereto, separating the resulted irreversibly crosslinked cellulose derivatives out of the reaction mixture, and optionally purifying and drying the resulted cellulose derivatives.