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Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing blocked‐isocyanate groups
Author(s) -
Chen YahnHaur,
Yang ChinPing
Publication year - 1994
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.1994.070510903
Subject(s) - cationic polymerization , isocyanate , copolymer , polymer chemistry , methacrylate , monomer , epoxy , materials science , chemistry , nuclear chemistry , organic chemistry , polymer , polyurethane
2‐Ethylhexanol–half‐blocked‐toluene diisocyanate (2EH‐half‐blocked TDI) was first reacted with 2‐hydroxyethyl methacrylate (HEMA) to prepare HEMA–TDI–2EH monomer containing blocked‐isocyanate groups. This monomer was reacted with butyl acrylate, styrene, and N,N ‐dimethylaminoethyl methacrylate to prepare an acrylic copolymer III ′ containing blocked‐isocyanate groups and tertiary amine groups. The acrylic copolymer III ′ can be mixed with an epoxy–amine adduct IV ′, acetic acid, and deionized (D.I.) water to from an electrodepositable coemulsion. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the codeposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer–surface (pricer) electrodepositable paint was also discussed. The results indicate that the deposition yield of cationic acrylic copolymer III is greater than that of cationic epoxy resin IV , i.e., the deposition velocity of III is faster than that of IV . However, resins III and IV can be well codispersed in D.I. water to form stable coemulsion; thus, the resin composition of deposited is almost equal to the resin composition. Moreover, the throwing power of coemulsion is almost equal to that of IV emulsion but greater than that of III emulsion. The optimum resin compositions of coemulsions for obtaining better gel content of deposited films are between 0.65 and 0.8 ( III/III + IV , by weight). © 1994 John Wiley & Sons, Inc.