Polymer heterogeneity in waterborne coatings

Abstract

An overview is presented of the progress in understanding polymer heterogeneity over the last 20 years and how this has contributed to the improvement of coatings. Solvent-based polymers are homogeneous in nature, since all polymeric materials tend to be dissolved in the same solvent mixture. This is different for most waterborne polymers, which tend to be present in a compartmentalized way. Most polymeric materials are present in particles, which are separated by the continuous aqueous phase. This gives excellent opportunities to create particle morphologies that form the basis for the film morphology after drying of the coating. This article gives an overview of the various types of heterogeneity which are accessible in waterborne polymers and will show how heterogeneity in the polymer can contribute to the solution of several persistent problems of the coating industry.

Outdoor weathering performance parameters of exterior wood coating systems on tropical hardwood substrates

“…An important factor in understanding the mechanism of coating failure during weathering is the resistance against internal, hygroscopic and thermal stress (Perera 1996). As waterborne coatings are more permeable to moisture due to their dispersed nature (Nicholson 1993;Overbeek 2010) they are exposed to higher stress levels at the woodcoating interface. An increased water permeability causes a swelling of the coating (de Meijer and Nienhuis 2009) followed by more frequent dimensional changes of the wood substrate.…”

The diacetone acrylamide crosslinking reaction and its control of core‐shell polyacrylate latices at ambient temperature

“…The contact angles of B 1 and B 2 are 70. 6 and 76.5 under the same conditions. Due to the smoother and denser network structure of coating film formed by keto-hydrazine crosslinking reaction that creates a three-dimensional network, water molecules cannot easily penetrate and thus the contact angle becomes larger.…”

“…To overcome these drawbacks, various crosslinking methods 5 and polymer heterogeneity 6 of latices were developed. The incorporation of crosslinking chemistry is recognized as a particularly effective means to enhance the mechanical strength, chemical stability, and solvent resistance of the coating film.…”

“…Moreover, to apply the concept of polymer particle heterogeneity is also an effective means to create new and improved materials of polymer latices. 6 For example, by using core-shell particles which have hard domains (formed from a high glass transition temperature (T g ) polymer) and soft domains (formed from a low T g polymer), it is possible to produce binders with a high block resistance and low minimum film-forming temperature (MFFT). 19,20 In this article, the crosslinkable core-shell PAs containing diacetone acrylamide (DAAM) [ Fig.…”

Preferred partitioning: the influence of coalescents on the build-up of mechanical properties in acrylic core–shell particles (I)

“…11 In addition, even under non-favorable film formation conditions (e.g., low temperature, high humidity, and in thick layer application) the coating system is still expected to deliver the desired performance. 12 Also here coalescents are often used to mitigate such non-favorable conditions. A clever design concept of the binder, e.g., applying multiphase particle technologies in combination with careful control over the coalescent compatibility of the different phases, can make a further reduction of the coalescent level feasible.…”