Patent GB-1116909-A (GB)
Title: A polymer latex for coating fabrics
IPC: D04H1/64
Filed: 1966-03-31
Abstract: A latex composition suitable for application to a woven fabric comprises an aqueous medium having dispersed therein a vinyl acetate-ethylene-N-methylolacrylamide interpolymer, said interpolymer containing 5-40% by weight of ethylene and, preferably, having a methylolacrylamide content of 0.5-10% by weight, with reference to the amount of vinyl acetate.  The interpolymer preferably has a particle size of 0.1 to 2m .  The composition is prepared by polymerizing the corresponding monomers in aqueous dispersion, preferably at a pH of 2 to 6 in the presence of a catalyst and emulsifying agent; in the preferred procedure an aqueous suspension of vinyl acetate is agitated in the presence of ethylene under pressure to effect dissolution of ethylene in the vinyl acetate while gradually heating the latter, and then catalyst and methylolacrylamide are added incrementally. Suitable catalysts include hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, ammonium or potassium persulphate and perborates; these may be used in conjunction with activators such as bisulphites, sulphoxylates, ferrous salts or tertiary atomatic amines.  Emulsifiers used are generally nonionic, e.g. ethylene oxide poly-condensation products with alcohols, alkylphenols, fatty acids, amides, amines, mercaptans and acetylenic glycols, and ethylene oxide-propylene oxide block polycondensation products.  An ionic emulsifier, e.g. sodium lauryl sulphate, may also be present.  The polymerization mixture may also include a latex stabilizer, e.g. a copolymerizable acid such as acrylic, methacrylic, itaconic, maleic or vinylsulphonic acid, or a protective colloid such as hydroxyethyl cellulose, polyvinyl alcohol, partially acetylated polyvinyl alcohol, casein, hydroxyethyl starch, carboxy methyl cellulose or gum arabic.  At the end of the polymerization the pH is adjusted to 4.5-7.  The latex composition provides heat-curable coatings, the curing of which is facilitated by including an acidic catalyst in the composition.ALSO:Compositions for application to woven fabrics to provide a back-coating or similar coating comprise an aqueous latex of a vinyl acetate-ethylene-N-methylolacrylamide interpolymer, the interpolymer containing 5-40% by weight of ethylene and, preferably, having a methylolacrylamide content of 0.5-10% by weight, with reference to the amount of vinyl acetate.  The interpolymer preferably has a particle size of 0.1 to 2 m .  The latex generally contains a nonionic emulsifier, e.g. an ethylene oxide polycondensation product; it may also contain an anionic emulsifier, e.g. sodium lauryl sulphate.  The latex may be stabilised by an unsaturated acid such as acrylic, methacrylic, itaconic, maleic or vinyl sulphonic acid, which may be present in copolymerised form as a component or the interpolymer, or by a protective colloid.  The fabric which is coated may be derived from fibres of cotton, wool, linen, cellulose acetate, nylon or "Dacron" (registered Trade Mark) or mixtures thereof.  The coating is suitably applied by means of the so-called licker-on apparatus wherein the fabric is passed across the upper portion of a rotatable roll, the lower portion of which is immersed in the latex contained in a trough, the temperature of the latex preferably being from 120 DEG  -140 DEG F.  Other coating processes can also be used, e.g. spraying.  The coating is then dried, e.g. at 240 DEG  - 250 DEG F, and cured, e.g. at 300 DEG  - 310 DEG F.  Curing can be facilitated by including an acidic catalyst in the latex.  The treated fabric has a desirable body and drape and is resistant to wet or dry cleaning.