Process for providing barrier properties to porous substrates

摘要

The invention relates to an improvement in a process for imparting barrier properties to porous substrates, such as, concrete, masonry products, and wood products. The process comprises the steps of: applying an aqueous based sealing composition comprising a polymeric resin to said porous substrate, evaporating the water and forming a water repellent coating of said polymeric resin on said porous substrate. The improvement comprises: deriving the polymeric resin from an aqueous based polymer emulsion comprising a polymer comprised of emulsion polymerized units of vinyl acetate and ethylene, preferably with a carboxylic acid monomer, the polymer containing amorphous and crystalline ethylene segments and having: (a) a crystalline melting point (T_m) ranging from 35 to 110° C., preferably 50 to 100° C.; measured at a heat rate of 20° C./minute; and, (b) a tensile storage modulus of at least 1x10⁵ dynes/cm² at 115° C. measured at 6.28 rad/sec.