Fluorine-modified additive for cementitious products, process for its preparation and use thereof

摘要

A fluoromodified admixture containing isocyanate and urethane and/or urea groups is described. Surprisingly, it has been found that the fluoromodified admixture according to the invention is outstandingly suitable even at a very low dosage for the permanent hydrophobic and/or oleophobic and/or dirt-repellent in-bulk finishing of products based on inorganic or hydraulic or mineral binders, without the fundamental property profile (e.g. compressive and flexural tensile strengths) of these products being substantially influenced. Moreover, it was not to be foreseen that in the case of the products treated with the fluoromodified admixtures according to the invention (e.g. hardened building material compositions) a markedly lower water absorption (avoidance of frost damage and corrosion) and a suppression of bleeding on the surfaces (avoidance of visual impairment) are to be observed. Furthermore, it could not be expected that in spite of the high fluorine modification an adequate self-dispersibility is afforded.