Film Formation of Vinyl Acrylic Latexes; Effects of Surfactant Type, Water and Latex Particle Size

By Gerald A. Vandezande, Alfred Rudin

The process of film formation from an 85/15 vinyl acetate/butyl acrylate latex was studied with respect to the effects of particle size and surfactant type on minimum film formation temperature (MFFT), glass transition temperature (Tg), drying rates, and optical clarity of the coalesced films.

Water plasticizes this polymer and thus only wet viscoelastic parameters and Tg values are realistic in film formation theories. The polymer is plasticized by ethoxylated alkylphenol non-ionic surfactants. The surfactants with shorter ethylene oxide chains are better plasticizers and poorer steric stabilizers than their longer analogs.

The type and concentration of stabilizing entities on the latex particle surfaces have very significant effects on the drying and coalescence properties of these latexes. Coalescence is somewhat faster with smaller latex particle sizes but larger particle size products dry at a faster rate than smaller ones in the absence of surfactant effects.