Patent GB-1381852-A (GB)
Title: Process for the preparation of polymer fibres
IPC: D01F6/04
Filed: 1973-04-17
Abstract: 1381852 Polymer fibres STAMICARBON BV 17 April 1973 [22 April 1972] 18487/73 Heading B5B  Polymer fibres are made by cooling a polymer solution and subjecting it to shearing forces while the polymer is in the course of precipitation; the polymer solution being mixed with a liquid identical with the solvent used for dissolving the polymer at such a temperature that the polymer precipitates from the resulting mixture, the said solution and liquid being introduced into a radially symmetrical space under conditions such that a rotary flow thereof is generated therein, subsequently removing the mixture of solvent and precipitated polymer from the radially symmetrical space, isolating the precipitated polymer fibres from the solvent, and recycling at least part of the solvent thus recovered through a heat exchanger to the said radially symmetrical space.  The polymer solution may be a solution of a polymer at least partly crystalline in the solid state, preferably one or more polymers of alpha-olefins, and the amount and temperature of the liquid introduced into the radially symmetrical space may be such that the mixture obtained after mixing with the polymer solution has a temperature slightly below, e.g., 5‹ to 15‹ C. below the precipitation temperature of the polymer. Specified solvents include propane, isobutane, pentane, hexane, cyclohexane, gasoline, pentamethyl heptane, halogenated hydrocarbons, benzene, toluene, xylene or mixtures of two or more thereof, hydrocarbons boiling below 100‹ C. being preferred. The polymer solution may be added to the liquid before the latter is introduced into the radially symmetrical space (or rotation chamber) or may be supplied to the vortex of the rotary flow. Discharging the mixture of solvent and precipitated polymer from the rotation chamber is preferably effected along the axis thereof. In apparatus as shown a radially symmetrical chamber 9 is provided with a tangentially disposed feedpipe 10 through which solvent is introduced, the temperature of which is controlled by passage through heat exchanger 17, the feed pressure being such that a rotary flow is generated in the chamber. A solution of the polymer is supplied through conduit 8 from heated mixing vessel 9, to which, for example, high density polyethylene is supplied through conduit 4 and solvent, e.g., pentamethyl heptane through conduit 2.  The mixture of solvent and polymer fibres which is precipitated flows through conduit 11 to centrifuge 12 and is separated and discharged at 13, and further treated to remove residual solvent. Separated solvent passes via conduit 14 and pump 15, which recycles the solvent through distributing valve 16, partly to vessel 1 through conduit 3 and partly to rotation chamber 9 through conduit 10. The fibres may also be separated (Fig. 2, not shown) by discharging the mixture into a closed collecting tank (29) containing a sieve belt (12<SP>1</SP>); fibres are blown off the lower face of the belt by a current of nitrogen, collected in a hopper and withdrawn by means of a screw conveyer (32). A number of rotation chambers may be arrayed in series (Fig. 3, not shown). Details of the rotation chamber construction are shown in Fig. 4. A cylindrical port 40 is fitted with feed port 41 having a solvent feed tube 42 fitted tangentially thereto. The feed conduit 43 for the polymer solution is so connected to 42 as to cause the polymer solution to be injected into the rotation chamber by the solvent. Alternatively, polymer solution may. be fed directly into the chamber via conduit 43<SP>1</SP>. The mixture of solvent and precipitated polymer fibres is discharged at 45, or conduit 43<SP>1</SP> can be used as an additional discharge line.