Patent GB-1011500-A (GB)
IPC: C08J3/00
Filed: 1964-01-13
Abstract: Aqueous dispersions of copolymers of at least 70 weight per cent of vinylidene chloride and 0.5 to 5 weight per cent of a component (i) comprising at least one monoethylenically unsaturated carboxylic acid or anhydride or partial ester thereof and 4 to 29.5 weight per cent of a component, (ii) comprising at least one monoethylenically unsaturated monomer other than a carboxylic acid or anhydride or partial ester thereof, said components (i) and (ii) each being soluble in water to the extent of at least 0.5 gm. per 100 c.c. at the temperature of polymerization, are prepared by polymerizing the vinylidene chloride and said components (i) and (ii) in aqueous medium in the presence of a water soluble salt of a peroxy acid and a sulphur-containing acid having reducing properties or an alkali metal salt thereof, and in the presence of less than 0.1 weight per cent based on the total monomer of any ionic emulsifying or dispersing agents and less than 2% by weight based on the total monomer of any non-ionic emulsifying or dispersing agents. Specified components (i) are acrylic, methacrylic, vinylacetic, crotonic, maleic, fumaric, itaconic, aconitic, citraconic and mesaconic acids and anhydrides and partial esters thereof. Specified components (ii) are acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylamide, methacrylamide, vinyl chloride, methyl vinyl ether, ethyl vinyl ether, methyl vinyl ketone and acrolein. Specified catalysts are alkali metal and ammonium peracetates, percarbonates and persulphates, and sulphurous acid and alkali metal sulphites, hydrosulphites, thiosulphates, formaldehyde sulphoxylates and metabisulphites. Non-ionic surface active agents, e.g. polyoxyethylated alcohols and alkyl phenols and esters thereof, hydrolysed polyvinyl acetate and ethylene oxide/propylene oxide copolymers; small proportions of ionic surface active agents, e.g. alkali metal sulphates and sulphonates of long chain alcohols; and chain transfer agents may also be present.  The dispersions have narrow particle size ranges, and dispersions of different particle size ranges may be blended. Emulsions of waxes, e.g. candelilla wax, may be added.  The dispersions may be used for coating substrates such as metal foils, paper, cardboard and films of thermoplastic polymeric materials.  Examples describe the copolymerization in aqueous dispersion in the presence of ammonium persulphate and sodium metabisulphite of vinylidene chloride and (1,2,5 and 15) acrylonitrile and acrylic acid, (3) acrylonitrile and methacrylic acid, (4) vinyl chloride and acrylic acid and (10) acrylonitrile and monobutyl itaconate; the addition to vinylidene chloride/acrylonitrile/acrylic acid copolymer dispersions of (7) polyoxyethylated sorbitan monostearate, polyoxyethylated nonyl phenol and sodium salt of sulphonated diesel oil, and (14) a dispersion of candelilla wax; and (12) the blending of dispersions of vinylidene chloride/acrylonitrile/acrylic acid copolymers of different particle sizes.ALSO:Substrates, e.g. of metal, paper, cardboard or thermoplastics, are coated with aqueous dispersions of copolymers of at least 70 weight per cent vinylidene chloride, (i) 0,5-5 weight per cent of a monoethylenically unsaturated carboxylic acid, anhydride or partial ester, and (ii) 4-29,5 weight per cent of at least one other monomer, said monomers (i) and (ii) being soluble in water to the extent of at least 0,5 gm. per 100 c.c. at the temperature of polymerization, prepared by copolymerizing the monomers in aqueous medium containing a water soluble salt of a peroxy acid and a reducing, sulphur-containing acid or alkali metal salt thereof, less than 0,05 weight per cent of any ionic and less than 2 weight per cent of any non-ionic emulsifying or dispersing agents, based on the weight of monomers.  The substrates may be of aluminium, aluminium foil/paper laminates, or thermoplastics such as polyethylene, polypropylene, polyvinyl fluoride, vinyl chloride polymers, cellulose acetate, regenerated cellulose and polyethylene terephthalate, which may be in the form of films, or sheets, channels or tubes which may be fabricated, e.g. into containers, after coating.  The substrates may be degreased before coating, and substrates such as polypropylene films may be pretreated with a corona discharge to improve adhesion. Copolymer dispersions of different particle size may be blended, and emulsions of waxes, e.g. candelilla wax, may be incorporated. Examples described the coating of aluminium foil with aqueous dispersions of (5) a vinylidene chloride/acrylic acid/acrylonitrile copolymer, with and without (7) polyethoxylated sorbitan monostearate, polyethoxylated nonyl phenol or sodium sulphonate of diesel oil; and (10) a vinylidene chloride/monobutyl itaconate/acrylonitrile copolymer; the coating of corona discharge treated biaxially oriented polypropylene film with aqueous dispersions of (6) a vinylidene chloride acrylic acid/acrylonitrile copolymer, with and without (8) polyethoxylated nonyl phenol; (12) a mixture of vinylidene chloride/acrylic acid/acrylonitrile copolymers of different particle size, and (14) a vinylidene chloride/acrylic acid/acrylonitrile copolymer and candelilla wax dispersion; the coating of regenerated cellulose film with aqueous dispersions of (11) vinylidene chloride/acrylic acid/acrylonitrile copolymers or vinylidene chloride/monobutyl itaconate/acrylonitrile copolymers, with and without sodium dodecylbenzene sulphonate; and the coating of polyvinyl chloride sheets with aqueous dispersions of (15) vinylidene chloride/acrylic acid/acrylonitrile copolymers.