Patent GB-1027330-A (GB)
Title: Coated fibrous web and coating composition therefor
IPC: D21H19/60
Filed: 1964-11-20
Abstract: Aqueous coating compositions comprise polyvinyl alcohol, a synthetic polymer latex, glyoxal and a mineral filler, the solids content of said composition being 35 to 70 weight per cent, the polyvinyl alcohol being present in amount of 3.5 to 6 parts, the synthetic polymer in amount of 7 to 11 parts and the glyoxal in amount of 0.5 to 1.5 parts per 100 parts by weight of mineral filler, and the weight of polyvinyl alcohol being at least one third of the weight of synthetic polymer.  Specified mineral fillers are clay, calcium sulphate, titanium dioxide, blanc fixe, lithopone, zinc sulphide and zinc oxide.  Specified synthetic polymers are styrene/butadiene copolymers, acrylonitrile/butadiene copolymers, styrene/isoprene copolymers, acrylic ester polymers and copolymers with methacrylates, styrene or acrylonitrile, and vinyl acetate polymers.  The compositions may also contain dispersing agents, e.g. tetrasodium pyrophosphate, and defoaming agents, e.g. tributyl phosphate, pine oil and ditertiary acetylenic alcohols; and may be used for coating paper and paperboard.  Examples describe aqueous compositions comprising polyvinyl alcohol, glyoxal, clay, titanium dioxide and tetrasodium pyrophosphate together with (1) a styrene/butadiene copolymer latex, tributyl phosphate and calcium stearate; (2) a stryene/butadiene copolymer latex and acetylenic alcohols; (3) acrylic polymer latex and acetylenic alcohols; and (4) polyvinyl acetate latex, tributyl phosphate and calcium stearate.ALSO:Fibrous substrates such as paper and paperboard may be coated with aqueous compositions comprising polyvinyl alcohol, a synthetic polymer latex, glyoxal and a mineral filler, the solids content of the composition being 35 to 70 weight per cent, the p  amounts of polyvinyl alcohol being 3.5 to 6 parts, the synthetic polymer being 7 to 11 parts and the glyoxal being 0.5 to 1.5 parts, all per 100 parts by weight of mineral filler, and the weight of polyvinyl alcohol being at least one third of the weight of synthetic polymer.  Specified fillers are clay, calcium sulphate, titanium dioxide, blanc fixe, lithopone, zinc sulphide and zinc oxide.  Specified synthetic polymers are styrene/butadiene, styrene/isoprene and acrylonitrile/butadiene copolymers; acrylic ester polymers or copolymers with methacrylates, styrene or acrylonitrile, and vinyl acetate polymers.  The compositions may also contain dispersing agents, e.g. tetrasodium pyrophosphate, and defoaming agents, e.g. tributyl phosphate, pine oil and ditertiary acetylenic alcohols. The compositions may be applied by trailing blade, roller or air knife coaters, and examples describe the trailing blade coating of paper board with aqueous compositions comprising polyvinyl alcohol, glyoxal, clay, titanium dioxide and tetrosodium pyrophosphate together with (1) a styrene/butadiene copolymer latex, tribuytyl phosphate and calcium stearate; (2) a styrene/butadiene copolymer latex and acetylenic alcohols; (3) acrylic polymer latex and acetylenic alcohols; and (4) polyvinyl acetate latex, tributyl phosphate and calcium stearate.ALSO:Paper and paperboard may be coated near the wet end of the machine with aqueous compositions comprising polyvinyl alcohol, a synthetic polymer latex, glyoxal and a mineral filler, the solids content of the composition being 35 to 70 weight per cent, the amounts of polyvinyl alcohol being 3.5 to 6 parts, the synthetic polymer being 7 to 11 parts and the glyoxal 0.5 to 1.5 parts, all per 100 parts by weight of mineral filler, and the weight of polyvinyl alcohol being at least one third of the weight of synthetic polymer. Specified fillers are clay, calcium sulphate, titanium dioxide, blanc fixe, lithopene, zinc sulphide and zinc oxide.  Specified synthetic polymers are styrene/butadiene, styrene/isoprene and acrylonitrile/butadiene copolymers; acrylic ester polymers or copolymers with methacrylates, styrene or acrylonitrile; and vinyl acetate polymers.  The compositions may also contain dispersing agents, e.g. tetrasodium pyrophosphate, and defoaming agents, e.g. tributyl phosphate, pine oil and ditertiary acetylenic alcohols. Examples describe the coating of paper board with aqueous compositions comprising polyvinyl alcohol, glyoxal, clay, titanium dioxide and tetrasodium pyrophosphate together with (1) a styrene/butadiene copolymer latex, tributyl phosphate and calcium stearate; (2) a styrene/butadiene copolymer latex and acetylenic alcohols; (3) acrylic polymer latex and acetylenic alcohols; and (4) polyvinyl acetate latex, tributyl phosphate and calcium stearate.