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Curing relations of hexakis(methoxymethyl)melamine and its combinations with acrylic polymers
Author(s) -
Saxon Robert,
Lestienne Firmin C.
Publication year - 1964
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1964.070080131
Subject(s) - melamine , thermosetting polymer , curing (chemistry) , methacrylic acid , melamine resin , catalysis , polymer chemistry , polymer , acrylic acid , materials science , condensation polymer , methylene , methanol , formaldehyde , condensation reaction , chemistry , organic chemistry , copolymer , coating
The curing of hexakis(methoxymethyl)melamine (HMM) alone and in blends with functionally substituted acrylic polymers was monitored by means of torsional braid analysis, infrared spectroscopy, weight change, and analysis of the volatile by‐products. HMM alone, when heated with a strong acid catalyst, forms thermoset condensation polymers which evidently have the same methylene‐bridged structure as conventional melamine‐formaldehyde resins; the major elimination product is methylal. When HMM is blended with an acrylic polymer containing methacrylic acid units, the acrylic chains are crosslinked by elimination of methanol and formation of methylene ester linkages between the acid groups and the melamine. The crosslinking reaction proceeds with or without strong acid catalysis and is many times faster than the self‐condensation of HMM. Acrylic polymers containing primary hydroxyl groups (derived from 2‐hydroxyethyl methacrylate) also undergo acid‐catalyzed reaction with HMM, and at a rate so much faster than analogous carboxylated polymers, that storage stability of the catalyzed resin becomes a serious problem. If a weaker catalyst, such as phthalic anhydride, is used, the curing reaction is very much slower. In order to develop the maximum number of new linkages, according to any of the experimental criteria, all of these systems must be heated for longer times, or at higher temperatures, than are customarily used in thermosetting resin technology. Thus the known utility and durability of such acrylic/melamine resins are achieved with only a fraction of the total number of crosslinks which are potentially capable of formation.