IMPROVEMENT OF SURFACE PROPERTIES OF NATURAL STONE BY MEANS OF ACRYLIC-SILOXANE HYBRID TREATMENT

Water-based hybrid materials have been synthesized by radical emulsion polymerization between acrylic monomers (mixtures of butyl acrylate, methyl methacrylate and acrylic acids) and vinylsilanes, and subsequent sol-gel reaction of the performed polymer with several amounts by weight of tetraethoxysilane (TEOS). Particle size of the different organic-inorganic polymer suspensions was quantified, obtaining average values of 141 nm. Chemical structure and thermal properties of copolymers were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC). The corresponding latex formulations have been then applied as coatings to the surface of natural stone, where good film formation, suitable adhesion and translucent properties are obtained according with Scanning Electron Microscopy (SEM) micrographs. The resulting hybrid coatings obtained after the curing process showed good tribological properties after microhardness and scratch resistance tests were made. Furthermore, chemical and stain resistance were determined, becoming more effective than nonhybrid polymeric coatings. On the other hand, slip resistance measurements performed to marble coated substrates demonstrated that polymer hybrid formulations with tetraethoxysilane contents up to 11.5% by weight are able to increase the slip resistance of natural stone compared to the non-hybrid analogue ones, obtaining promising results in this aspect.