RHEOLOGICAL CONSIDERATIONS WHEN FORMULATING HIGH HIDING PAINTS UTILIZING PRE-COMPOSITE POLYMERS

摘要

Pre-composite polymer was introduced into the coatings industry as a means to increase the light scattering efficiency of TiO_2. These latex binders, designed to adsorb onto the surface of TiO_2, allow for a more uniform distribution of the pigment resulting in an increase in its intrinsic hiding efficiency. Formulators can take advantage of this intrinsic hiding efficiency and use these polymers in a wide array of paints, including paints with the market claim of 'one coat hide'. These types of high performance paints tend to employ high TiO_2 levels and high volume solids, making rheological adjustments more challenging than traditional lower volume solids formulations. The introduction of pre-composite polymers have taken a challenging formulating task and added complexity. This paper describes a working mechanism for the fundamental contribution to rheology and offers a hypothesis as to why the distinct shape of a polymer-pigment composite drives increased viscosity. The Krieger-Dougherty equation will be used to estimate the composite rheology contribution. This mechanistic understanding can be used by formulators to guide their current efforts in developing high quality, high intrinsic hiding paints. Dow's future work will focus on the interactions of polymer-pigment composite and additives, thus enhancing the latitude of pre-composite polymer in the growing segment of high quality, high hiding paints.