PAPPERSLIM

摘要

1487913 Cationic oligourethanes BAYER AG 20 Aug 1976 [23 Aug 1975] 34779/76 Heading C3R [Also in Division D2] A cationic sizing agent for paper comprises a solution in water or in a mixture of water and a water miscible organic solvent, e.g. an alcohol, of an oligourethane Mol. Wt. 500 to 5000 having protonated and/or quarternized ammonium groups. The oligourethanes may be obtained by reacting a polyioscyanate, e.g. diphenyl methane 4,41 diisocyanate or the mixed phosgenation products of aniline/formaldehyde (technical MDI), with a polyalkanol, particularly an N-alkyl diethanolamine having a total of from 5 to 12 carbon atoms and optionally with a chain terminator, e.g. N,N- dimethylamino ethanol in a solvent, e.g. isopropanol. The amino-nitrogen atoms of the oligourethane are at least partially protonated and/or quaternized by reaction with an acid and/or a quaternizing agent during or subsequent to the polyisocyanate/polyalkanolamine reaction. Suitable polyalkanolamines are N- methyl, N-ethyl, N-cyclohexyl and N-benzyl diethanolamines, triethanolamine and tetrapropoxylated ethylene diamines. The required cationic groups may also be provided before the polyisocyanate/alkanolamine reaction by using quaternized or protonated derivatives of the polyalkanolamines. Suitable quaternizing agents are epichlorohydrin, methyl sulphate and benzyl chloride and suitable protonating agents are formic and acetic acids. The mainly organic solution of the protonated and/or quaternized oligourethane obtained on completion of the reaction is diluted with water or aqueous acids, e.g. formic and acetic to give solutions having solids contents of 5 to 57% by weight which can be stored and transported in this concentrated form and from which the ready to use sizing agent may be obtained by further dilution with water to give solutions having a 0À02 to 10% by weight solids content. The sizing agents may be used to size a wide range of papers including those containing acidic neutral or basic filling materials, e.g. chalk, talc or casein. They may be applied by mixing with the paper pulp, by subsequent immersion or spraying of the sheet and by coating on to the surface of the paper using a glue press.