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Syntheses and properties of cationic amine–epoxy adducts and their use in electrodeposition: I. Diethanolamine/diethylamine terminated cationic epoxy with pendant 2‐ethylhexanol‐blocked TDI groups
Author(s) -
Yang ChinPing,
Chen YahnHaur
Publication year - 1991
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.1991.070420423
Subject(s) - diethanolamine , diethylamine , epoxy , cationic polymerization , chemistry , polymer chemistry , acetic acid , triethanolamine , diglycidyl ether , bisphenol a , nuclear chemistry , materials science , organic chemistry , analytical chemistry (journal)
Alkyl partially blocked toluene diisocyanate (PBTDI) and hydroxyl group‐containing polyepoxide were mixed to produce a blocked TDI–epoxy resin and then reacted with secondary amine and treated with acetic acid to give a cationic resin. In this study, six cationic resins (IV‐A and IV‐B, two series) were synthesized from three diglycidyl ethers of bisphenol A with different epoxy equivalent weights of 508, 650, and 950, and two secondary amines (diethylamine and diethanolamine). Acetic acid was used as the neutralization agent and ethylene glycol mono‐ n ‐butyl ether (butyl cellosolve, BCS) and deionized water were utilized as the emulsion solvents. Some properties of electrodeposition, such as throwing power and rupture voltage, and some physical and chemical properties of the deposited films were investigated. It was found that the appearance of emulsion, deposition yields, and quality of the deposited films are strongly dependent on pH, BCS, and resin contents. To obtain suitable deposition properties and stable emulsions from IV‐A and IV‐B systems, the aqueous dispersion should meet the following conditions: pH, 5.5‐6.0; BCS contents, 3.0–5.0 wt %; and resin concentration, 7.0–9.0 wt %. For both systems, the deposited films had good appearance, adhesion, hardness, and alkali reagent resistance. The salt spray resistance and acid resistance of films deposited from series III‐A (epoxy resin formulations containing diethylamine) are superior to films deposited from series III‐B (epoxy resin formulations containing diethanolamine).