Process for melt spinning acrylonitrile polymer hydrates

Claim 1

In a process for spinning acrylonitrile polymer filaments comprising addition to the polymer of water in an amount equivalent as a minimum to either 45% of that required to hydrate all the nitrile groups in the polymer or 80% of that required to hydrate the coupled nitrile groups (on a 1/1 water molecule/nitrile group basis), whichever is larger, and as a maximum the amount of water actually combined as hydrate plus 7 weight percent based on polymer, the total water not exceeding the amount necessary to hydrate all the nitrile groups in the polymer, heating the composition under at least autogenous pressure at a temperature ranging between about 25° C. less to about 10° C. more than the temperature of hydration as determined by Laser Raman Spectroscopy and extrusion of the resulting composition under pressure through an orifice to form a shaped product, the improvement comprising use of an acrylonitrile polymer containing at least 91% by weight acrylonitrile units and up to 9% by weight of one or more copolymeric units, having an intrinsic of 0.6 to 2, 7 to 23 μeq./g. enolizable groups after mild acid treatment, 15 to 70μ eq./g. thioether ends derived from a water insoluble mercaptan and less than 3 μeq./g. oxidizable hydrolysis fragments.