Processes for manufacture of sulfonated melamine-formaldehyde re

Details Processes for manufacture of sulfonated melamine-formaldehyde re Processes for manufacture of sulfonated melamine-formaldehyde re

1993-05-17

1995-06-13

Michl, Paul R.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From aldehyde or derivative thereof as reactant

524528, 524843, 528255, 528388, C08G 1230

Patent

active

054243904

ABSTRACT:
A process of producing an aqueous solution of a sulfonated melamine-formaldehyde resin. The process comprises condensing melamine and formaldehyde or a precursor of formaldehyde (e.g. paraformaldehyde) in an aqueous mixture having a pH in the range of 8-10 to form a reaction mixture containing a condensation product of melamine and formaldehyde. The condensation product is then reacted in an aqueous mixture having a pH of 8-10, preferably 8-9, with a sulfonating agent to produce a mixture containing a sulfonated condensation product. Finally, polymerizing the said sulfonated condensation product in an aqueous mixture having a pH of 5-7 to form a resin solution. In the process, at least one of the sulfonation step and the polymerizing step is carried out under superatmospheric pressure (generally 5 to 70 p.s.i.) and at an elevated temperature of, in the case of the sulfonating step, 100.degree.-130.degree. C. for a time of 1 to 5 hours or of, in the case of the polymerizing step, 105-150.degree. C. for a time of 15 minutes to three hours. Modifications of the basic process involve carrying out the sulfonation of the formaldehyde before the condensation of the melamine and formaldehyde or reacting all of the melamine, formaldehyde or precursor and the sulfonating agent all together under superatmospheric pressure. The resulting aqueous solution, or the dried resin extracted therefrom, has low salt content and is suitable as a superplasticizer for concrete mixes.

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Encyclopedia of Chemical Technology, third edition, vol. 2, Kirk-Othmer-pp. 454, 458-459, 468.

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