Patent GB-916245-A (GB)
Title: Emulsion coating compositions and method of making same
IPC: C09D157/00
Filed: 1959-03-26
Abstract: A coating composition suitable for forming a water-insoluble film is made by dispersing a pigment having a hydrophilic character in an aqueous solution of a water-soluble organosilicon compound which has at least one carbonsilicon bond through which a hydrocarbon or chlorinated hydrocarbon group of 1 to 20 carbon atoms is attached to silicon, and at least one oxygen-containing group having only one valence of an oxygen atom attached to silicon and the other attached to carbon, hydrogen or lithium, potassium, sodium, ammonium or substituted ammonium, for bonding with the surface of the pigment, and incorporating the dispersion so produced in an aqueous dispersion of a fusible or heat-treatable filmforming material.  As organosilicon compounds there may be used any of the water-soluble siloxanes or siloxanates mentioned in U.S.A. Specifications 2,763,629 and 2,799,598 and similar compounds in which the vinyl group is substituted by alkyl, aryl, alicyclic, chlor-alkyl or alkenyl groups; water-soluble alkyl, or alkenyl alkoxysilanes, and other water-soluble alkoxysilanes having a hydrocarbon or chloro-substituted hydrocarbon group attached to silicon through a carbon-silicon bond; water-soluble aryl or aralkylsiloxanes having a hydrocarbon group and hydroxyl or ester groups bonded directly to silicon; and all other water-soluble siloxanes having a hydrocarbon group bonded directly to silicon and having a hydroxyl, alkoxy or OM group, where M is lithium, potassium, sodium, ammonium or substituted ammonium, one oxygen valence being attached to silicon.  The hydrocarbon or chlorinated hydrocarbon groups must have not more than 20 carbon atoms.  Pigments mentioned include red iron oxide, lithopone, titanium dioxide, barytes, zinc oxide, silica, aluminium oxide, lead oxides, lead carbonate, lead chromate and carbon black. An example describes the incorporation of a dispersion of a mixture of red iron oxide, lithopone and titanium dioxide in water containing hydrolysed vinyl triethoxysilane and wetting agents, into a latex of a graft polymer prepared by copolymerizing butadiene and styrene and grafting thereon methyl methacrylate or a mixture of methyl methacrylate and acrylonitrile.  The product, which is suitable as a primer for alkyd resin enamel top coatings, is sprayed on a phosphate-coated steel panel, dried and fused.  Where the coating over the primer is deposited from aqueous dispersion, this may also incorporate the reactive silicone compound.  Resinous materials which may be used include alkyd resins, polyvinyl halides, polyvinyl acetate, copolymers of vinyl chloride and vinyl acetate, polystyrene, polymethylmethacrylate and copolymers of methyl methacrylate and other acrylates, copolymers of styrene with 2-ethylhexyl acrylate and methacrylic acid or acrylonitrile, or both, and graft polymers of a mono-olefine on rubbery polymers and copolymers of diolefinic compounds, including polymers of butadiene, chloroprene, isoprene, dimethylbutadiene and copolymers of these with styrene or acrylonitrile.ALSO:A coating composition suitable for forming a water-insoluble film is made by dispersing a pigment having a hydrophilic character in an aqueous solution of a water-soluble organosilicon compound which has at least one carbonsilicon bond through which a hydrocarbon or chlorinated hydrocarbon group of 1 to 20 carbon atoms is attached to silicon, and at least one oxygen-containing group having only one valence of an oxygen atom attached to silicon and the other attached to carbon, hydrogen or lithium, potassium, sodium, ammonium or substituted ammonium, for bonding with the surface of the pigment, and incorporating the dispersion so produced in an aqueous dispersion of a fusible or heat-treatable filmforming material.  As organosilicon compounds there may be used any of the water-soluble siloxanes or siloxanates mentioned in U.S.A. Specifications 2,763,629 and 2,799,598 and similar compounds in which the vinyl group is substituted by alkyl, aryl, alicyclic, chlor-alkyl or alkenyl groups; water-soluble alkyl, or alkenyl alkoxysilanes, and other water-soluble alkoxysilanes having a hydrocarbon or chloro-substituted hydrocarbon group attached to silicon through a carbon-silicon bond; water-soluble aryl or aralkyl-siloxanes having a hydrocarbon group and hydroxyl or ester groups bonded directly to silicon; and all other water-soluble siloxanes having a hydrocarbon group bonded directly to silicon and having a hydroxyl, alkoxy, or OM group, where M is lithium, potassium, sodium, ammonium or substituted ammonium, one oxygen valence being attached to silicon.  The hydrocarbon or chlorinated hydrocarbon groups must have not more than 20 carbon atoms.  Pigments mentioned include red iron oxide, lithopone, titanium dioxide, baryates, zinc oxide, silica, aluminium oxide, lead oxides, lead carbonate, lead chromate and carbon black.  An example describes the incorporation of a dispersion of a mixture of red iron oxide, lithopone, titanium dioxide, barytes, zinc oxide, taining hydrolysed vinyl triethoxysilane and wetting agents, into a latex of a graft polymer prepared by co-polymerizing butadiene and styrene and grafting thereon methyl methacrylate or a mixture of methyl methacrylate and acrylonitrile.  The product is sprayed on a phosphate-coated steel panel, dried and fused.  Where a subsequent coating is deposited from aqueous dispersion, this may also incorporate the reactive silicone compound.  Resinous materials which may be used include alkyd resins, polyvinyl halides, polyvinyl acetate, copolymers of vinyl chloride and vinyl acetate, polystyrene, polymethylmethacrylate and copolymers of methyl methacrylate and other acrylates, copolymers of styrene with 2-ethyl-hexyl acrylate and methacrylic acid or acrylonitrile, or both, and graft polymers of a monoolefine on rubber polymers and copolymers of diolefinic compounds, including polymers of butadiene, chloroprene, isoprene, dimethylbutadiene and copolymers of these with styrene or acrylonitrile.