Preparation and performance of silicone-acrylic latex for exterior wall coating of dirt pickup resistance

Abstract

A self-cross-linkable core-shell silicone-acrylic latex and coatings with excellent dirt pickup resistance were studied to solve the pollution problem for the exterior wall. This article focused on adding two silicon compounds with CC in the core and shell at the influence on latex and coating performance, respectively. First, the octamethylcyclotetrasiloxane (D4) and tetramethyltetraethylcyclotetrasiloxaneand (D4V) were used to synthesize silicone copolymer (PVMS) by cationic ring-opening polymerization as the core. Next, in this silicone latex, butyl acrylate (BA), methyl methacrylate (MMA), methacrylic acid (MAA), and γ-methacryloxypropyltrimethoxysilane (A174) were copolymerized to form the silicone-acrylic latex (PVMS/ASI). Fourier Transform Infrared Spectrometers proved that PVMS was successfully grafted onto acrylic copolymer (ASI). The morphology of particles exhibited core-shell structure, which was clearly shown in TEM. Finally, a comprehensive study of the effect of D4V in the PVMS/ASI was conducted on the properties of such latexes, films, and coatings. It was found that the D4V content influenced quite significantly the properties of latexes and films (water absorption, contact angle, crosslinking degree) as well as the properties of coatings (dirt pickup resistance, water resistance, hardness, adhesion, water scrub resistance). Ultimately, it found that D4V had a positive effect on dirt pick-up. When D4V content was 23 wt% in PVMS/ASI, the coating had an excellent dirt pickup resistance with extremely low ΔR (2.65%).