Water-Resistant Latex Coatings: Tuning of Properties by Polymerizable Surfactant, Covalent Crosslinking and Nanostructured ZnO Additive

Jana Machotová,Petra Mácová,Denisa Steinerová,Andréa Kalendová,Stanislav Šlang,Jaromír Šňupárek,Jan Vajdák

doi:10.3390/coatings11030347

Abstract

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided by nanostructured ZnO additive) were investigated. The latexes were prepared by the standard emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as the main monomers. The addition of surface-untreated powdered nanostructured ZnO was performed during latex synthesis, resulting in stable latexes comprising dispersed nanosized additive in the content of ca 0.9−1.0 wt.% (based on solids). The coating performance with emphasis on water resistance was evaluated. It was determined that the application of the polymerizable surfactant improved coating adhesion and water-resistance, but it wasn′t able to ensure high water-resistance of coatings. Highly water-resistant coatings were obtained provided that covalent intra- and interparticle crosslinking together with ionic crosslinking were employed in the coating composition, forming densely crosslinked latex films. Moreover, coatings comprising nanostructured ZnO additive displayed a significant antibacterial activity and improved solvent resistance.

Highlights

Development of ecological coatings has attracted particular interest in coating and paint industry, where acrylic latex binders are of considerable interest due to their favorable properties, such as low cost, resistance to atmospheric conditions, ease of preparation, modification and pigmentation
Diacetone-acrylamide (DAAM) with adipic acid dihydrazide (ADH) is the most favored combination used in the self-crosslinking latexes [10,11,12]
The most remarkable feature of the keto-hydrazide crosslinking reaction is fast curing at room temperature, providing minimal consumption of energy during processing and easy applicability in case of recoating substrates

Summary

Introduction

Development of ecological coatings has attracted particular interest in coating and paint industry, where acrylic latex binders are of considerable interest due to their favorable properties, such as low cost, resistance to atmospheric conditions, ease of preparation, modification and pigmentation They have the disadvantage of water sensitivity of coatings, which often limits their practical application in high-performance products. As reflected by number of publications and patents, there has been particular interest in one-pack acrylic coating compositions curable at room temperature [4,5,6] Among these materials, self-crosslinking systems based on keto-hydrazide crosslinking reaction have been shown to be effective [7,8,9]. The most remarkable feature of the keto-hydrazide crosslinking reaction is fast curing at room temperature, providing minimal consumption of energy during processing and easy applicability in case of recoating substrates

Methods

Results

Conclusion