Patent GB-359000-A (GB)
Title: Improved manufacture of olefine polysulphide plastic compounds
IPC: C08G75/16
Filed: 1930-07-02
Abstract: Rubber-like olefine polysulphides are produced by treating olefine dihalides with polysulphide solutions as described in Specification 302,270, [Class 2 (iii), Dyes &c.], in presence of a dispersing agent while maintaining a hydroxyl ion concentration at least equal to that in a saturated aqueous solution of precipitated magnesium hydroxide. Suitable dispersing agents are precipitated magnesium hydroxide, peptized starch, gelatin, glue, blood-albumen or egg-albumen.  The product is a latex-like dispersion which can be coagulated, with or without the previous incorporation of compounding or stabilizing materials, and it may be used to impregnate or coat fabrics and non-absorbent materials after which it is coagulated.  Preferably an excess of one or other of the reagents is employed; the polysulphide may be previously stabilized by heating until homogeneous as described in Specification 360,890; and the conditions of the reaction, particularly as regards temperature, may be controlled by adding alcohols, for instance in proportions of 10-80 per cent by volume. In an example using calcium polysulphide with magnesium hydroxide as dispersing agent, the latter is formed in the polysulphide solution by adding first sodium hydroxide and then a magnesium salt, yielding a semi-gelatinous dispersion.  The ethylene dichloride is then added gradually, leaving the polysulphide in slight excess.  The latex produced separates into a layer which is washed with water.  In another example sulphur is dissolved in sodium hydroxide to form Na2S4 and the solution boiled for 20 hours, magnesium hydroxide being dispersed in the solution as before after which ethylene dichloride is added.  The dispersion may be coagulated by adding an acid, such as hydrochloric, sulphuric, acetic or formic acid.  Litharge zinc, oxide, magnesia or the like, and inert materials such as wood flour, carbon black, glue and asbestos may be compounded with the plastic coagulum, for instance in a rubber mill, the mixture being heated to 80 DEG  C. or upwards, for instance in an autoclave under 40 lbs. steam pressure.  Alternatively the compounding material such as litharge or zinc oxide may be mixed with the latex and which is then coagulated.  The product resembles soft rubber, but is insoluble in rubber solvents and is not affected by soft water or oils.  It may be used as a dielectric.  The latex may be preserved alone or with the compounding materials therein; if stored for a week or more it undergoes a change such that the addition of acid p  would produce a granular product, but it can be restored to its original condition (before the addition of acid) by heating for a few minutes above 100 DEG  C.  If the polysulphide employed contains less than 3 atoms of sulphur dispersions are still obtained, but with less resemblance to latex, and granular or pulverulent products may be obtained.  Instead of the olefine dihalides, halogen compounds with the unsaturated hydrocarbons produced in pressure cracking and natural gas cracking may be used. Specification 354,394 also is referred to.ALSO:Rubber-like olefine polysulphides are produced by treating olefine dihalides with polysulphide solutions as described in Specification 302,270, [Class 2 (iii), Dyes &c.], in presence of a dispersing agent, while maintaining a hydroxyl ion concentration at least equal to that in a saturated aqueous solution of precipitated magnesium hydroxide. Suitable dispersing agents are precipitated magnesium hydroxide, peptized starch, gelatin, glue, blood-albumen or egg-albumen.  The product is a latex-like dispersion which can be coagulated, with or without the previous incorporation of compounding or stabilizing materials; and it may be used to impregnate or coat fabrics and non-absorbent materials, after which it is coagulated.  Preferably an excess of one or other of the reagents is employed; the polysulphide may be previously stabilized by heating until homogeneous as described in Specification 360,890; and the conditions of the reaction, particularly as regards temperature, may be controlled by adding alcohols, for instance in proportions of 10-80 per cent by volume. In an example, using calcium polysulphide with magnesium hydroxide as dispersing agent, the latter is formed in the polysulphide solution by adding first sodium hydroxide and then a magnesium salt, yielding a semi-gelatinous dispersion.  The ethylene dichloride is then added gradually, leaving the polysulphide in slight excess.  The latex produced separates into a layer which is washed with water.  In another example sulphur is dissolved in sodium hydroxide to form Na2S4 and the solution boiled for 20 hours, magnesium hydroxide being dispersed in the solution as before, after which ethylene dichloride is added.  The dispersion may be coagulated by adding an acid, such as hydrochloric, sulphuric, acetic or formic acid.  Litharge, zinc oxide, magnesia or the like, and inert materials such as wood flour, carbon black, glue and asbestos may be compounded with the plastic coagulum for instance in a rubber mill, the mixture being heated to 80 DEG  C. or upwards, for instance in an autoclave under 40 lbs. steam pressure.  Alternatively the compounding material such as litharge or zinc oxide may be mixed with the latex and which is then coagulated.  The product resembles soft rubber, but is insoluble in rubber solvents, and is not affected by salt water or oils.  It may be used as a dielectric.  The latex may be preserved alone or with the compounding materials therein; if stored for a week or more it undergoes a change such that the addition of acid would produce a granular product, but it can be restored to its original condition (before the addition of acid) by heating for a few minutes above 100 DEG  C.  If the polysulphide employed contains less than 3 atoms of sulphur dispersions are still obtained, but with less resemblance to latex, and granular or pulverulent products may be obtained.  Instead of the olefine dihalides, halogen compounds with the unsaturated hydrocarbons produced in pressure cracking and natural gas cracking may be used. Specification 354,394 also is referred to.ALSO:Rubber-like olefine polysulphides are produced by treating olefine dihalides with polysulphide solutions as described in Specification 302,270, [Class 70, Indiarubber &c.], in presence of a dispersing agent while maintaining a hydroxyl ion concentration at least equal to that in a saturated aqueous solution of precipitated magnesium hydroxide. Suitable dispersing agents are precipitated magnesium hydroxide, peptized starch, gelatin, glue, blood-albumen or egg-albumen.  The product is a latex-like dispersion which can be coagulated, with or without the previous incorporation of compounding or stabilizing materials. Preferably an excess of one or other of the reagents is employed; the polysulphide may be previously stabilized by heating until homogeneous as described in Specification 360,890; and the conditions of the reaction, particularly as regards temperature may be controlled by adding alcohols, for instance in proportions of 10-80 per cent by volume.  In an example using calcium polysulphide with magnesium hydroxide as dispersing agent, the latter is formed in the polysulphide solution by adding first sodium hydroxide and then a magnesium salt, yielding a semi-gelatinous dispersion.  The ethylene dichloride is then added gradually, leaving the polysulphide in slight excess.  The latex produced separates into a layer which is washed with water.  In another example sulphur is dissolved in sodium hydroxide to form Na2S4 and the solution boiled for 20 hours, magnesium hydroxide being dispersed in the solution as before after which ethylene dichloride is added.  The dispersion may be coagulated by adding an acid, such as hydrochloric, sulphuric, acetic or formic acid.  Litharge, zinc oxide, magnesia or the like, and inert materials such as wood flour, carbon black, glue and asbestos may be compounded with the plastic coagulum for instance in a rubber mill, the mixture being heated to 80 DEG  C. or upwards, for instance in an autoclave under 40 lbs. steam pressure.  Alternatively the compounding material, such as litharge or zinc oxide may be mixed with the latex and which is then coagulated.  The product resembles soft rubber, but is insoluble in rubber solvents and is not affected by soft water or oils.  It may be used as a dielectric.  The latex may be preserved alone or with the compounding materials therein; if stored for a week or more it undergoes a change such that the addition of acid would produce a granular product but it can be restored to its original condition (before the addition of acid) by heating for a few minutes above 100 DEG  C.  If the polysulphide employed contains less than 3 atoms of sulphur dispersions are still obtained, but with less resemblance to latex, and granular or pulverulent products may be obtained.  Instead of the olefine dihalides, halogen compounds with the unsaturated hydrocarbons produced in pressure cracking and natural gas cracking may be used. Specification 354,394 also is referred to.