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US 6,673,970 B1Granted
Process for preparing methylene diphenylamines by partial neutralization of acidic methylene diphenylamines
AssigneeBayer Polymers LLC
InventorsLouis Renbaum, Mark S. Solomon, William D. Tippins
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Abstract
Disclosed herein is a process for preparing a reaction product containing methylene diphenylamine, comprising reacting aniline and formaldehyde in the presence of an acid catalyst wherein the acid level of the resulting reaction mixture is reduced during digestion of the reaction mixture.
Claims1
An isocyanate material which is prepared by phosgenating a reaction product containing methylene diphenylamine prepared by (a) reacting aniline and formaldehyde in the presence of a catalyst;
- selected from the group consisting of hydrochloric acid, hydrobromic acid, sulfuric acid, triflouroaceticacid, methanesulfonic acid, phosphoric acid, formic acid, acetic acid, and citric acid (b) reducing the acid level of the resulting mixture during digestion of the reaction mixture;
- and (c) completely neutralizing the reaction product after digestion.
Dependencies are inferred from the claim text.