Patent GB-458130-A (GB)
Title: Improvements in and relating to apparatus for purifying rubber latex and like dispersions
IPC: C08C1/04
Filed: 1935-06-17
Abstract: <PICT:0458130/III/1> <PICT:0458130/III/2> <PICT:0458130/III/3> <PICT:0458130/III/4> Rubber latex and similar liquids are purified from soluble crystalloid impurities by dialysis with water or aqueous solutions under such conditions that hydrostatic pressure is exerted on the liquid undergoing dialysis to promote movement thereof at the dialysing surface while simultaneously retarding or reversing the dilution of the liquid by incoming water.  Suitable apparatus comprises an assemblage of thin cells separated from each other by diaphragms e.g. of vegetable parchment paper.  Alternate cells contain water and the intermediate cells latex or other liquid under dialysis.  The water cells are connected in series in a circuit containing a circulating pump, a heating tank, means for the discharge of water laden with impurities from the latex and a supply of fresh water.  In the arrangement shown in Fig. 1, both the water cells 1 and the latex cells 2 are connected in series, latex being supplied from a tank 6 and discharged into tank 9. The latex cells are maintained under pressure by a compressed air system 11, the pressure being maintained constant by a liquid seal 12.  Fig. 2 illustrates an alternative arrangement comprising two groups 20 and 21 of latex cells 2, the aligned latex cells of the two groups being interconnected by pipes 22 and the cells 2 of group 20 being connected in common to an air pressure system via pipe 23, and those of group 21 via pipe 24.  Both sets of cells 2 are half-filled with latex, the latex being forced wholly into the cells of group 21 by application of pressure through pipe 23, and the movement being reversed by applying pressure through pipe 24. On completion of dialysis, pressure is applied to pipes 23 and 24 and the latex forced out through pipes 22 and 25.  Alternatively, the aligned latex cells may be formed as twin compartments of a common cell structure, having a central partition foreshortened at its lower end to allow the latex to pass to-and-fro between the compartments.  Fig. 6 shows an assemblage of cells with two pairs of cells 2 coupled to each other and to high and low pressure air systems 11 and 45 respectively through three-way valves 40 and 41. The latex is moved from the left-hand pair of cells 2 to the right-hand pair and vice versa, by suitable operation of the valves 40 and 41.  If desired, a closed pressure system may be used when using gases other than air or for recovery of volatile constituents, e.g. ammonia from latex, the low pressure system being connected through a reservoir and compressor with the high pressure system.  Fig. 8 shows a cell construction in which the latex cells are thinner than the walls of the cell.  The framework 46 of a water cell is separated from the adjacent frames 48 of the latex cells by gaskets 47.  The diaphragms 19 are reinforced by wire nets &c. 49 which are bridged by spacer blocks 50.  The central spacer block or blocks are wider than the remainder so that each face of each water cell is rendered convex, thus reducing the effective thickness of the interposed latex cells. Specification 430,426 is referred to.