Ionic Crosslinked Acrylic Elastomers Synthesized by One-Pot Method Using Ionic Crosslinking Agent, Part 1: Preparation of Ionic Crosslinking Agent, and Effect of Ionic and Covalent Crosslinking for Physical Properties in Acrylic Elastomers Synthesized by One-Pot Method

The reaction product(ZMAPH)of 1-methacryloyloxyalkyl-2-hydrogen phthalate(MAHP, alkyl: ethy1/i-propy1=1/1 mole)and ZnO was sufficiently soluble in n-butyl acrylate(BA), methyl methacrylate(MMA)or styrene. From IR spectrum, it was estimated that ZMAPH was zinc salt hydrate of MAHP. The elastomers were synthesized by radical copolymerization of BA/MMA(7/3wt.), ZMAPH as ionic crosslinking agent, and/or 1, 2-di(methacryloyldioxy ethyl)phthalate(DMDP) as covalent crosslinking agent. The structure of crosslinking was examined by swelling data and dynamic mechanical analysis. The tensile strength and compression set of elastomers by DMDP were low, and those by ZMAPH were high. The elastomers by DMDP/ZMAPH showed high tensile strength and low compression set. The density of crosslinking by DMDP, obtained from Nielsen's egation, was low, and it by ZMAPH remarkably rose with increasing content of ZMAPH. These results suggest that the ionic crosslinking is composed of weak bond and fine structure, but the covalent crosslinking is composed of strong bond and rough structure.