Applicator with hydrophobic coating transferable to contacting surface

#The present invention in general relates to a hydrophobic coating composition and in particular to a wiper blade imparting a hydrophobic film to a contacted window through wiper usage.

#Rain, sleet, and snow have always presented a vision problem for the operator of a vehicle. While mechanical movement of a wiper blade across a windshield is partly effective as a mechanical squeegee to displace water and snow from a windshield. The operation of a conventional wiper blade, regardless of whether made of carbon-base or silicone rubbers, is only partially effective in clearing water and snow from a windshield. A wiper blade moving across a windshield leaves a thin film of water that partly impairs vision and promotes adhesion of additional liquid water or snow to the windshield. Additionally, as a wiper blade undergoes degradation through exposure to the environment, the uniformity of wiper blade contact with the windshield is degraded. Additionally, debris that commonly adheres to the windshield creates regions in which wiper blade is gapped from the windshield surface leading to vision obscuring streaks and water droplets.

#To address limitations of windshield cleaning through mechanical squeegee action, hydrophobic glass treatment solutions have been applied to automotive windshields to improve driver vision under high humidity conditions of rain, sleet, or snow. Representative of such glass treatments are those detailed in U.S. Pat. Nos. 3,579,540, 5,688,864, 6,432,181. While such glass treatments are effective in rendering the windshield hydrophobic so as to cause water to bead and not forth windshield water film, these products have met with limited acceptance owing to the labor-intensive application, and somewhat toxic chemicals needed to be handled to create a hydrophobic windshield surface. Additionally, the application of such hydrophobic glass treatment while a windshield is being subjected to rain or other precipitation is impractical.

#The present invention is further detailed with respect to the following drawing. This figure is not intended to limit the scope of the present invention but rather illustrate certain attributes thereof.

#FIG. 1 is a plot of water contact angle in degrees as a function of wiper blade wipe cycles on automotive windshield glass for inventive compositions under various storage and application conditions; and

#FIG. 2 is a plot of water contact angle in degrees as a function of wipe cycles for various commercially available water repellency wiper blades where reduced contact angle is consistently noted relative to the inventive compositions of FIG. 1.

#The present invention has utility as a vehicle windshield wiper having a coating that imparts a hydrophobic film to the contacted glass surface. While the present invention is largely detailed with respect to windshields, it is appreciated that other suitable target surfaces of usage for the present invention illustratively include manual squeegees, vehicle rear windows, aircraft exterior surfaces, and other exterior surfaces where water repellency is desired. The present invention has the attribute of long term storage stability coupled with the ability to even after storage, impart a hydrophobic film to a contacted surface. While the present invention largely details the inventive coating composition as being applied to a surface via a wiper blade, it should be appreciated that an inventive coating composition is readily applied to a surface on which a hydrophobic film is desired with resort to other applicators illustratively including a buffing pad or cloth.

#An inventive coating composition includes a silicone oil that is liquid at 20° C. It is appreciated that a silicone oil operative herein readily includes a mixture of oils that vary in molecular weight, monomer subunits, or a combination thereof. A silicone oil operative in the present invention is a polydialkylsiloxane having a formula: —(—Si(R1)(R2)—O—)m— where R1 and R2 are in each occurrence independently H, C1-C10 alkyl, a substituent containing C1-C10 alkyl, C6-C12 aryl, or a substituent containing C6-C12 aryl; and M is an integer value of from 2 to 2230. A substituent is an alkyl or aryl in which a proton thereon is replaced with a moiety illustratively including hydroxyl, amino, fluorine, or vinyl. Perfluoro silicone oils are also explicitly noted as being operative in an inventive coating composition. While the amount of silicone oil present in an inventive coating composition varies somewhat based on operating use conditions, a silicone oil component is chosen to have a viscosity of from between 2 and 1,000,000 mm2/s at 25° C. and a surface tension of less than 30 dynes per centimeter (dynes/cm). A silicone oil is typically present in certain embodiments from 1 to 95 total weight percent of a coating composition and in still other embodiments from 10 to 60 total weight percent of an inventive coating composition. An exemplary oil component of an inventive coating composition includes a silicone oil. Specific silicone oils operative herein illustratively include polydimethylsiloxane, decamethylcyclopentasiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, amino-functional polydimethylsiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, carboxyl-functional polydimethylsiloxane, carbinol-functional polydimethylsiloxane, phenol-functional polydimethylsiloxane, fluoro-functional polydimethylsiloxane, epoxy-functional polydimethylsiloxane, alkyl-functional polydimethylsiloxane, polyether-functional polydimethylsiloxane, and combinations thereof.

#An inventive coating composition also includes a silicone resin soluble in a solvent along with the oil component or in the silicone oil component alone. A silicone resin is chosen such that upon being applied to a substrate promotes formation of a hydrophobic film thereon. Resins operative herein illustratively include a resin component of an inventive coating composition illustratively includes a, silicone-modified urethane resin, silicone-modified epoxy resin, silicone resin, perfluoro-silicone resin, a partially fluorinated silicone resin, C1-C6 alkyl-modified silicone resin, phenyl-modified silicone resin, silicone-modified acrylic resin, and combinations thereof It is appreciated that high lubricity and hydrophobicity are desirable characteristics of a resin or resin combination in an inventive coating composition. Equally important, the chosen resin is highly soluble in the silicone oil.