Verfahren zum UEberziehen einer langgestreckten,flexiblen Unterlage

1285585 Coated yarns EI DU PONT DE NEMOURS & CO 30 Oct 1969 [31 Oct 1968] 53341/69 Heading B2E [Also in Division D1] An elongated flexible substrate is coated by advancing through a heating zone at greater than 500 yards per minute so as to heat it to at least 80‹C. but below the melting point of the substrate, applying an unheated liquid mixture comprising a polymeric coating material and an inert solvent of boiling point at least 80‹C. but below the melting point of the polymer to the advancing heated substrate, the speed and temperature of the substrate being sufficient to vapourise the solvent and dry the polymer material on the substrate in the form of an adherent coating of thickness less than one-fifth of the thickness of the substrate. The process is applicable to the sizing of yarns and filaments prior to weaving and knitting. The yarns may be composed of cotton, wool; polyesters, polyacrylics, and especially polycarbonamide. Examples of polycarbonamides are given. The coating mixture may be applied by roller, doctor knife, spraying and may comprise polyacrylic acid and a finish oil, e.g. a mineral oil or long chain fatty acid ester. In a typical example, polyhexamethylene adipamide is melt-spun through a spinnerette, an antistatic aqueous finish comprising polyethylene glycol di-2-ethylhexoate is applied, the yarn then passed to a pair of draw rolls heated to 190‹C. around which the yarn is wrapped, and then the heated yarn passed to a size applicator roll. The sizing mixture was prepared by adding 126 parts of a 25% aqueous polyacrylic acid solution to 400 parts of a stirred emulsion comprising 70.2 parts butyl stearate, 4.0 parts polyoxyethylene sorbitol hexaoleate, 8.3 parts fatty acid esters of higher polyglycols, 2.3 parts oleic acid, 7.5 parts long chain alkyl phosphate, and 1.7 parts potassium hydroxide added as a 45% solution in water, diluted with water to provide a 12% emulsion.