| 摘要 |
The invention relates to porous mouldings, a process for the production thereof, and a suitable apparatus for carrying out the process. The process comprises forcing a homogeneous, single-phase liquid mixture of one or more polymers and one or more mixture partners which are liquid at the preparation temperature of the mixture through a nozzle from top to bottom at a linear velocity V1 into a cooling liquid which does not dissolve the polymer at the cooling temperature, or only does so to an insignificant extent. The cooling liquid is kept in a channel-like zone surround by a wall from the point at which the extruded mixture enters the cooling liquid until at least the point at which solidification commences, the velocity of the cooling liquid in this zone V2 being kept smaller than V1; V2 may also be 0 or have the opposite sign to V1. The cooling liquid is preferably kept in a cooling device in the shape of a U-tube, in which the level is controlled by metering in at the inlet and/or outlet point. The process is particularly suitable for the production of mouldings such as membranes, in particular hollow fibre membranes made from hydrophilic polymers, such as polyamides, and made from polymers of low molecular weight, and for the processing of polymer/mixture partner mixtures having a relatively low polymer content. |
