High PVC film‐forming composite latex particles via miniemulsification, part 3: Optical properties

Abstract

ABSTRACT:The optical properties of films cast from latexes comprising TiO 2 particles encapsulated in poly(styrene-co-n-butyl acrylate) prepared by miniemulsification and having high loading (11-70% pigment volume concentration (PVC)) were investigated. Contrast ratio (CR) measurements for all batches showed that a 3 mil film (obtained at 43% PVC) was the minimum thickness at which 98% CR could be achieved. Also, the greatest hiding power (HP) (535 ft 2 /gal) was obtained at 43% PVC. In addition, gloss measurements showed that as the TiO 2 loading increased, the gloss decreased, indicating that the increasing amount of TiO 2 contributed to a reduction in the surface smoothness. The effects of surfactant concentration (sodium lauryl sulfate) on the encapsulated particle size and the optical properties of the encapsulated films for the 11% PVC system are described. The effect of varying the sonifier operating conditions on the TiO 2 particle size, encapsulated particle size, and the optical properties of the encapsulated films for the 43% PVC system was also investigated. A comparative study of the optical properties of films cast from encapsulated latex particles with films cast from physical blends of polymer particles and pigment at the same TiO 2 loading and film thickness was made. The optical properties (i.e., CR and gloss) showed a clear advantage of the miniemulsification process over the blends.

Latex Imaging by Environmental STEM: Application to the Study of the Surfactant Outcome in Hybrid Alkyd/Acrylate Systems

“…In addition, the localization of the surfactant in the film has a strong effect on the application properties. Thus, surfactant migration reduces gloss , and adhesion , when it accumulates on the film surface and increases water sensitivity when it forms aggregates inside the film. , Kientz et al listed three primary locations for surfactants upon film formation: (i) surfactant dissolution in the polymer, (ii) formation of a continuous membrane at the internal polymer/polymer interfaces, and (iii) formation of islands of surfactant throughout the film and interfaces (film/air and film/substrate), which have been determined using numerous techniques: Fourier transform infra red − attenuated total reflection (FTIR-ATR), atomic force microscopy (AFM), − energy filtering transmission electron microscopy (EF-TEM), and freeze fracture, Rutherford backscattering spectroscopy (RBS) . However, most of the reported results concern model acrylic or polystyrene latex films and, to our knowledge, no information concerns hybrid systems.…”

Isolation of the effect of the hairy layer length on the mechanical properties of waterborne coatings

“…They are necessary to impart colloidal stability to the polymer particles but, on the other hand, they may present serious drawbacks in the final film applications. During the film formation, most commonly used anionic surfactants may migrate to the film interfaces or form aggregates in the interior of the films reducing properties such as gloss or adhesion and increasing water sensitivity [1][2][3][4][5][6][7]. A strategy to avoid this negative influence is to use macromolecular surfactants with reduced mobility.…”

The colloidal properties of alkaline‐soluble waterborne polymers

“…As a result, the surfactants can form separate phases and become locked in interstices between the particles in the coating during film formation . This can adversely affect various coating properties such as adhesion, haze formation, gloss, and water sensitivity …”