| 摘要 |
Heat-hardenable resinous alkylolated unsaturated amide-containing copolymers are made by forming an organic solvent solution containing a mixture of monoethylenic monomers including a vinylidenic amide, an aldehyde or an aldehyde precursor, a free-radical polymerization catalyst and at least 0.1%, based on the total weight of monomers, of an alkaline catalyst, and maintaining the solution at elevated temperature to cause polymerization and simultaneous reaction of amido hydrogen atoms with the aldehyde modifying agent. Etherification of the product may be effected by including a C1-C8 alcohol in the reaction mixture. Amide monomers specified are acrylamide, methacrylamide and itaconic diamide. As comonomers for use with the amides there may be used styrene, alkyl styrenes, halostyrenes, methyl methacrylate, alkyl acrylates, maleic acid and its anhydride and esters and butene-2. Aldehydes and precursors thereof specified are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, furfural, paraformaldehyde, trioxymethylene and hexamethylenetetramine. Polymerization catalysts specified are organic peroxides, hydroperoxides and peresters, and azodiisobutyronitrile. The resulting copolymer solutions are used in coating surfaces, for which purpose they may be combined with solvent-soluble heat-hardenable condensates of formaldehyde with urea, melamine, or benzoguanamine, polyepoxides, e.g. the diglycidyl ether of 2,21-bis-(p-hydroxyphenyl propane), and alkyd resins, e.g. a condensation product of dehydrated castor oil, phthalic anhydride, benzoic acid and glycerine, or the product obtained by copolymerizing a mixture of methyl methacrylate and styrene with a condensation product of dehydrated castor oil, glycerine and phthalic anhydride. Titanium dioxide pigment may be added to the coating compositions. The examples describe the preparation of amide copolymers, using the following ingredients: (a) monomers: acrylamide, styrene and ethyl acrylate, with one or more of vinyl stearate, methyl acrylate and butyl acrylate as optional comonomers, (b) aldehyde: formaldehyde, (c) polymerization catalyst: a mixture of di-tert.-butyl peroxide and azobisisobutyronitrile, (d) etherifying alcohol: n-butanol, (e) alkaline catalysts: triethylamine or ammonium hydroxide, (f) other ingredients: xylol and ethylene glycol monobutyl ether as solvents, and tert.-dodecyl mercaptan. In the processes described the various ingredients are added gradually to the reaction vessel as polymerization proceeds.ALSO:Steel panels, either bare or pre-treated, are coated by applying thereto a composition made by the organic solvent solution polymerization of a mixture of monoethylenic monomers including a vinylidenic amide, an aldehyde or aldehyde precursor and optionally, an alcohol, to produce a copolymer containing alkylol or alkoxyalkyl groups in place of amido hydrogen atoms. After application, the coating is hardened by heating at 250-350 DEG F. Also present in the coating compositions may be aminoplasts, e.g. condensates of formaldehyde with urea, melamine or benzoguanamine, alkyd resins, e.g. a condensation product of dehydrated castor oil, phthalic anhydride and glycerine, and the copolymerization product thereof with a mixture of methyl methacrylate and styrene, and polyepoxides. The compositions may also contain titanium dioxide as a pigment. The examples describe the use of coating compositions derived from formaldehyde-butanol modified copolymers of acrylamide, styrene and ethyl acrylate, containing, optionally, one or more of methyl acrylate, butyl acrylate and vinyl stearate as comonomers. |
