Abstract: In a process for preparing a polyamide based on dicarboxylic acids and diamines in an extruder, a solid mixture comprising a monomer mixture composed of 50 mol % of dicarboxylic acid mixture composed of from 60 to 88 % by weight of terephthalic acid and from 12 to 40% by weight of isophthalic acid, in which up to 20% by weight of the dicarboxylic acid mixture may also be replaced by other dicarboxylic acids, and 50 mol % of hexamethylenediamine which may be up to 20% by weight replaced by other C2-30-diamines, in a corotatory twin-screw extruder for a residence time of from 10 seconds to 30 minutes, is heated to a temperature in the range from 150 to 400° C. while removing steam and if appropriate diamines through venting orifices.

Abstract: The process for preparing a polyamide based on dicarboxylic acids and diamines has the following stages: 1) providing an aqueous monomer mixture of dicarboxylic acids and diamines, the molar ratio of dicarboxylic acids to diamines being adjusted such that a molar deficiency of dicarboxylic acids or diamines of from 1 to 10 mol % is present at the outlet of stage 3), based on the other component in each case, 2) transferring the aqueous mixture from stage 1) to a continuous evaporator reactor in which diamines and dicarboxylic acids are reacted at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, 3) transferring the mixture from stage 2) to a separator which is operated at a temperature in the range from 100 to 370° C.

Abstract: In a process for preparing a polyamide based on dicarboxylic acids and diamines in an extruder, a solid mixture comprising a monomer mixture composed of 50 mol % of dicarboxylic acid mixture composed of from 60 to 88 % by weight of terephthalic acid and from 12 to 40% by weight of isophthalic acid, in which up to 20% by weight of the dicarboxylic acid mixture may also be replaced by other dicarboxylic acids, and 50 mol % of hexamethylenediamine which may be up to 20% by weight replaced by other C2-30-diamines, in a corotatory twin-screw extruder for a residence time of from 10 seconds to 30 minutes, is heated to a temperature in the range from 150 to 400° C. while removing steam and if appropriate diamines through venting orifices.

Abstract: The process for preparing a polyamide based on dicarboxylic acids and diamines has the following stages: 1) providing an aqueous monomer mixture of dicarboxylic acids and diamines, the molar ratio of dicarboxylic acids to diamines being adjusted such that a molar deficiency of dicarboxylic acids or diamines of from 1 to 10 mol % is present at the outlet of stage 3), based on the other component in each case, 2) transferring the aqueous mixture from stage 1) to a continuous evaporator reactor in which diamines and dicarboxylic acids are reacted at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, 3) transferring the mixture from stage 2) to a separator which is operated at a temperature in the range from 100 to 370° C.

Abstract: Semiaromatic semicrystalline thermoplastic polyamide molding compositions, comprising A) from 40 to 100% by weight of a copolyamide composed of a1) from 30 to 44 mol % of units which derive from terephthalic acid a2) from 6 to 20 mol % of units which derive from isophthalic acid a3) from 42 to 49.5 mol % of units which derive from hexamethylenediamine a4) from 0.5 to 8 mol % of units which derive from aromatic diamines having from 6 to 30 carbon atoms, where the molar percentages of components a1) to a4) together give 100%, and B) from 0 to 50% by weight of a fibrous or particulate filler C) from 0 to 30% by weight of an elastomeric polymer D) from 0 to 30% by weight of other additives and processing aids, where the percentages by weight of components A) to D) together give 100%.

Abstract: A method for the continuous monitoring of the coating of a yarnlike dielectric material with assistants comprises applying a solution of said assistants dissolved in a polar solvent to said yarnlike material, then passing said yarnlike material between the electrodes of a downline capacitive measuring element, determining the capacity changes of said downline capacitive measuring element, and using said capacity changes to calculate the unevenness of the layer thickness of the applied solution.

Abstract: The invention relates to an apparatus for positioning a plurality of scanning devices, in particular magnetic heads, over preselected tracks on a stack of at least two rotatable recording disks in a memory processing unit, in which apparatus the single-beam section of the supporting arm of the magnetic heads has been produced integral with the head tower and is provided with mounting means for at least one magnetic head on a spring-supporting means, in particular for a pair of magnetic heads previously connected to one another, so that it is possible to replace any head or pair of heads. The apparatus can be used in magnetic storage systems, industrial production equipment etc.

Abstract: A disk drive unit is provided with an electromagnetic releasing/arresting device for the head support, in order to prevent the head and the disk record from being damaged when the drive unit is shipped, handled or switched off. The novel electromagnet has a low power consumption and small dimensions, is economical to manufacture and exhibits high operational reliability.

Abstract: A head positioning device for a disk drive unit comprises a Y-shaped drive band for displacing the carriage bearing the head(s), each divergent arm portion of the Y forming the same angle with the central longitudinal axis of the band. In another embodiment, the two divergent arm portions are connected together by a crosspiece. Advantageously, the drive band is made of steel having a tensile strength of from 1200 to 2500 N/mm.sup.2, especially from 2000 to 2500 N/mm.sup.2. The novel positioning device can be used with advantage in any type of system for recording, reproducing and storing audio, video, data or control signals.