Patent GB-853483-A (GB)
Title: Dry-spinning of aqueous polymer dispersions
Filed: 1957-01-31
Abstract: Shaped structures e.g... fibres and films having at least one small dimension of the order of 1-20 mils. are made by extruding an aqueous dispersion containing from 40-70% by weight of one or more water-insoluble thermoplastic dadition polymers each having a second order transition point of at least 25 DEG C. and containing from 0-5% of a water-soluble polymer into an atmosphere the temperature of which is at least 180 DEG C. through an orifice having at least one small dimension of the order of 1-20 mils, the shaped structures being "self supporting" (as hereinafter defined) and non-thermally degraded.  Preferably the aqueous dispersion which is extruded has a viscosity not exceeding 1,8 poises.  Self supporting is defined as having sufficient strength to be handled.  The aqueous dispersions of polymers may be obtained by any known method e.g. by emulsion polymerization procedures. When the shaped structures comprise fibres, spinnerets may be used having more than one orifice, and in addition to being round the orifices may be oval and eliptical in cross section, rectangular and slot-like orifices being used to produce ribbons or films. The heated atmosphere used to coagulate the extruded aqueous dispersion stream may flow con- or countercurrently with said dispersion stream.  The shaped structures may be collected with or without stretching.  The stretching may be effected between 70 and 300 DEG C. by passage over a heated plate or between a pair of godets. Esters of acrylic or methacrylic acid with or without other comonomers such as acrylonitrile, methacrylonitrile, vinyl chloride, styrene and vinyl acetate provide addition polymers suitable for preparing spinning dispersions.  The polymers may contain polar or hydrophilic groups e.g. hydroxyl and carboxyl groups.  Hydroxy pentyl vinyl ether is specified as a monomer having the desired polarity and the presence of epoxy groups e.g. in glycidyl acrylate or methacrylate make them suitable dispersion components. Monoethylenically unsaturated compounds which can be homopolymerized or copolymerized in the presence of a free radical catalyst to produce dispersion polymers, are esters, ethers, amides, nitriles, aldehydes, ketones, hydroxyethers, hydroxyesters, ureidocontaining ethers and esters, hydrocarbons, halides, anhydrides and carboxylic acids.  Specified examples of these compounds are alkyl esters of acrylic, methacrylic and itaconic acids in which the alkyl groups has 1-18 carbon atoms. The dispersions may contain in addition a fusion aid e.g. adiponitrile.  In examples (1) an aqueous dispersion of acrylonitrile/butoxy ethyl acrylate copolymer is dry spun into filaments (2) an aqueous dispersion of acrylonitrile/3:3:5 trimethylcyclohexyl acrylate is emulsion polymerized and dry spun (3) an aqueous dispersion of methyl acrylate/acrylonitrile copolymer is dry spun into filaments which are subsequently heat stretched (4) an aqueous dispersion of acrylonitrile/butoxyethyl acrylate/5-hydroxy - pentyl vinyl ether copolymer is dry spun and the resulting filaments given a toluene diisocyanate cross linking after treatment. (5) an aqueous dispersion of acrylonitrile, trimethyl cyclohexyl acrylate/b -hydroxy vinyl sulphide is emulsion polymerized in the presence of methyl succinonitrile and dry spun and (6) aqueous dispersions of a methyl methacrylate/ethyl acrylate copolymer and polyvinyl acetate are dry spun.  Specifications 786,755 and 846,890 are referred to.