Patent GB-622746-A (GB)
Title: Methods and apparatus for producing cellulose xanthate
IPC: D01F2/08
Filed: 1946-07-19
Abstract: <PICT:0622746/IV (a)/1> <PICT:0622746/IV (a)/2> <PICT:0622746/IV (a)/3> Cellulose xanthate of uniform consistency is obtained by agitating a mass of particulate alkali cellulose with carbon disulphide until an intimate physical mixture of the two is obtained, terminating the agitation when the physical mixture has been obtained and then allowing the chemical reaction to proceed to completion while avoiding the application of external forces tending to impart relative movement to the solid particles of the mass.  Referring to Fig. 1, alkali cellulose crumbs and atomized carbon disulphide are fed to the member 2 from hopper 11 and nozzle 12 respectively.  The member 2 comprises a chamber 8 wherein the materials are agitated by rotating blades 15 and a chamber 9 wherein the materials are allowed to react.  The agitating and/or reaction chambers may be jacketed for cooling or heating.  The chambers 8, 9 are temporarily separated by one of the plates 24 which is fed from magazine 25 to the junction 20 by pistonrod 26, the plate being held in position by shoes 31, 32 (Figs. 2 and 3) carried by reciprocable rods 29, 30.  On completion of the agitation in chamber 8, the shoes 31, 32 are retracted and the plate 24 carrying the batch of thoroughly <PICT:0622746/IV (a)/4> <PICT:0622746/IV (a)/5> agitated reactants is dropped into the reaction chamber 9.  The reaction chamber 9 is normally filled with a plurality of batches separated from each other by plates 24 and which move intermittently downwardly, one batch being introduced at the top of the chamber as one is withdrawn from the bottom.  A pair of shoes 35, 36 carried by reciprocable rods 33, 34 support the lowermost plate 24 in zone 9 and retraction of rods 33, 34 releases the plate and its load which are then discharged on to a platen 37 adapted to be lowered by piston-rod 40 on to a support 38.  Platen 37 carries a detached ring 41 with projecting lugs 42 which, when the platen is in its lowest position, engage with lugs 46a carried on the end of piston-rod 45, so that motion of rod 45 serves to move the plate 24 and its batch clear of the platen 40 when they are dumped down the shoot 43.  The ring 41 is carried along a guideway 47 and is finally retracted to its original position.  In a modification, the batches in the reaction chamber are stacked without the provision of intervening plates 24, reciprocable plates serving as opening and closing means at the top and bottom of the chamber.  Means for feeding alkali cellulose crumbs into the agitating chamber while preventing escape of gas from the system are shown in Fig. 6, and comprise a freely rotatable member 67 mounted in chamber 66, the member 67 being divided into a series of alternate open and closed compartments by partitions 68.  The partitions are so disposed that when an open section registers with shoot 70, a closed section registers with hopper 11, and the weight of crumbs effects rotation of the member 67 to bring an open section into register with hopper 11. Means are also described for introducing a measured amount of carbon disulphide into the agitating chamber.  In a further modification (Fig. 9), a plurality of feeding compartments 159, 160 and 161 are provided to permit alkali cellulose crumbs to be fed continuously to the chamber 162 while preventing escape of gas from the system, the compartments being temporarily sealed from one another by tiltable plates 167, 168.  Atomized carbon disulphide is fed to agitating chamber 162 through pipe 180, and the feeding and discharge of crumbs to and from the chamber is effected by reciprocable discs 166, 179.  The reaction chamber comprises horizontal chambers 156, 158 connected by shoot 157. Material discharged from zone 162 is pushed along chamber 156 by a hydraulically reciprocated cylinder 186 until it falls into chamber 158 wherein it is pushed along by a similar cylinder 193a and is finally picked up by worm conveyer 200 and discharged down shoot 202. In all the modifications, the various reciprocable elements and motors are electrically operated and controlled so that the several operations are effected sequentially and in a predetermined unit of time.  Specification 570,687 is referred to.