Preparation Of Multifunctionalambient Self-Curable Acrylate Latex

Ambient self-curable latex (ASCL) is being increasingly used in fabricating water-borne adhesives and coatings because of its good desirable performances. However, there is a limited number of ASCL that satisfy commercial applications due to various reasons, especially poor shelf stability of the latex.In the present work, a novel ambient self-curable acrylate latex with long-term stability was prepared by mixing colloidal dispersions in water of a chlorine-functionalized copolymer and a amino-functionalized copolymer. The cross-linking occurred via the quatemization between the two types of functional groups when the latex was applied to a surface and dried at ambient condition. The chlorine-functionalized polymer dispersion and the amino-functionalized one were prepared by conventional emulsion copolymerization using vinyl monochloroacetate (CVA) as chloride functional monomer and N,N-Dimethylaminoethyl methacrylate (DMAEMA) as amino-monomer, respectively.The dosage of initiator, emulsifier, functional monomer and pHs were investigated to figure out suitable polymerization formulation and condition. It was found that, during emulsion copolymerization using DMAEMA as amine-containing monomer, polymerization of such monomer occurred in aqueous phase due to its high water solubility and DMAEMA-rich polymer thus generated might dissolve in water phase. This phenomenon is believed to have strong effect on the stability of latex colloids during both polymerizing stage and storage stage of the polymer emulsion. It is known that homo-poly(PDMAEMA) is water soluble and its solubility is sensitive to temperature and pH. Therefore, phase transition behavior and colloid formation of PDMAEMA in aqueous solution were investigated by dynamic light scattering at different temperatures, pHs, ionic strength and in the presence of emulsifier, SDS. It is concluded that basic pH in aqueous phase is required to achieve a good stability of amino-containing polymer emulsion and the ASCL dispersion.The ASCLs prepared based on the optimized formulation exhibited high cross-linking activity and excellent stability during300days of shelf storage. The gel content of the dried films of the ASCLs were larger than80%. The mechanical properties of the dried films were determined. Typically, the tensile strength was14.5MPa, the elongation rate was about450%, and the Young’s modulus was2.04MPa.Moreover, emulsifier-free emulsion polymerization was employed to prepare the two functional emulsions. It was expected that the negative effect of emulsifier on film property of ASCL could be eliminated if no surfactant was used in emulsion polymerization. The ASCL obtained by blending the two functional polymer dispersions also exhibited good shelf stability (>6months).