Process for preparing an aqueous solution of sulfanilic acid modified melamine-formaldehyde resin and a cement composition

• Main Authors: NAKAYAMA, KEISUKE, UCHIDA, JUN, SUDOH, YUHJI, SUGIYAMA,TAKAICHI
• Format: Patent
• Language: English; French; German
• Published: 26.04.2000
• Edition: 7
• Subjects: ARTIFICIAL STONE; CEMENTS; CERAMICS; CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDINGMATERIALS; CONCRETE; LIME, MAGNESIA; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; REFRACTORIES; SLAG; THEIR PREPARATION OR CHEMICAL WORKING-UP; TREATMENT OF NATURAL STONE

The present invention relates to a process for preparing in aqueous solution of sulfonated melamine-formaldehyde resin, and a cement composition in which the solution and a setting retarder are added to a concrete, a mortar, a cement paste or the like. And the process comprises the following step (A), step (B) and step (C): Step (A): a step of adjusting an aqueous solution containing melamine (a), formaldehyde (b), sulfanilic acid (c) and an alkali substance (d) to (a):(b):(c)=1:2.5-3.5:0.5-1.5 in molar ratio and its pH to B.0-13.5, and thereafter heating the aqueous solution at 50-90 DEG C to conduct the reaction until free sulfanilic acid decreases to 40-90 mol% of the amount of sulfanilic acid charged; Step (B): a step of adding an inorganic acid to the reaction liquid obtained in the step (A) to adjust its pH to 6.0-8.0, and thereafter heating the reaction liquid at 50-90 DEG C. to conduct the reaction until free sulfanilic acid decreases to 20-60 mol% of the amount of sulfanilic acid charged; Step (C): a step of adjusting a pH of the reaction liquid obtained in step (B) to 7.0-13.5.