Water-borne pressure-sensitive adhesives: Effects of acrylic acid and particle structure

摘要

Two types of core-shell pressure-sensitive adhesive latexes have been prepared by semi-continuous emulsion polymerization: (a) soft-soft latexes with a poly(n-butyl acrylate) core and a poly[(n-butyl acrylate)-co-(acrylic acid)] (PBA/AA) shell; and (b) rigid-soft latexes with a poly[(methyl methacrylate)-co-(allyl methacrylate)] (PMMA/ALMA) core and a PBA/AA shell. Three series of soft-soft latexes were prepared in which: (i) the acrylic acid level in the PBA/AA shell was fixed at 5 mol% and the volume percentage (vol%) of the PBA/AA shell was varied; (ii) the vol% of the PBA/AA shell was varied, but with the acrylic acid level in the shell also being varied such that the total acrylic acid level was constant at 5 mol%; and (iii) the PBA/AA shell was fixed at 20 wt% of the total polymer and the acrylic acid level was varied from 0 to 49 mol%. In the rigid-soft latexes, the acrylic acid level in the PBA/AA shell was fixed at 5 mol% and the vol% of the PBA/AA shell was varied. The latexes were adjusted to pH 5.5 using aqueous ammonia solution before being used to form adhesive bonds between Melinex and glass, for measurement of shear resistance, and between Melinex and steel for measurement of peel adhesion. The pressure-sensitive adhesive properties of the latex coatings are interpreted in terms of the effects of the changes in latex particle acrylic acid content and particle structure on the interfacial and bulk properties of the adhesive materials. [References: 3]