Patent GB-612011-A (GB)
Title: Improvements in or relating to the production of foam generating compositions
IPC: A62D1/02
Filed: 1945-09-19
Abstract: Foam-generating agents are prepared by subjecting a sulphur-containing proteinaceous material selected from the class consisting of keratins, globulines, albumens and h moglobulins to the action of a metal oxide or hydroxide of lead, zinc, cadmium, mercury, cobalt, nickel, copper and thallium in the presence of a non-acid aqueous medium having a pH value not exceeding 10, in a closed vessel at a temperature between 110 DEG  and 200 DEG  C., the quantity of metal oxide used being at least equal to the amount required to convert to the sulphide of the metal the sulphur present in the protein material, so precipitating this chemically reactive sulphur as insoluble metal sulphide and thereby continuously and substantially removing such sulphur from the reaction medium.  The aqueous medium may contain an alkali such as ammonia but then weak solutions with a molar concentration of the alkali below 0.25 are used.  Reaction may be effected at between 110 DEG  to 200 DEG  C. for a period between 24 hours and 45 minutes; a graph (not shown), illustrates suitable variations of the time of the reaction with temperature in the treatment of dried blood with litharge. Preferably the treatment is carried out until about 50 per cent of the protein nitrogen is converted into soluble form.  In an example, dried blood, litharge and water are heated together in a sealed autoclave at 140 DEG  C. for 4 hours, then filtered, dissolved lead precipitated by addition of zinc dust and the solution again filtered and concentrated.  A table summaries the results obtained by digestion of dried blood as above with oxides of lead, zinc, cadmium, mercury, cobalt, nickel and copper and thallium hydroxide.  The compositions, when stabilised and admixed with water and gas, will produce foams suitable for extinguishing fires.  Specification 601,956 is referred to.  The Specification as open to inspection under Sect. 91 describes the hydrolysis of any sulphur-containing proteinaceous material by means of the above-mentioned metal oxides or hydroxides, in the presence of an aqueous medium at a temperature between 105 DEG  and 200 DEG  C.; it is stated that dissolved metal in the hydrolysate may be precipitated by means of a finely-divided metal which precedes it in the electrochemical series.  This subject-matter does not appear in the Specification as accepted.ALSO:Foam generating agents are prepared by subjecting a sulphur-containing proteinaceous material selected from the class consisting of keratins, globulins, albumins and haemoglobulins to the action of a metal oxide or hydroxide of lead, zinc, cadmium, mercury, cobalt, nickel, copper and thallium in the presence of a non-acid aqueous medium having a pH valve not exceeding 10, in a closed vessel at a temperature between 110 DEG  and 200 DEG  C., the quantity of metal oxide used being at least equal to the amount required to convert to the sulphide of the metal the sulphur present in the protein material, so precipitating this chemically-reactive sulphur as insoluble metal sulphide and thereby continuously and substantially removing such sulphur from the reaction medium (see Group IV (b)).  In an example, dried blood, litharge and water are heated together in a sealed autoclave at 140 DEG  C. for 4 hours, then filtered, dissolved lead precipitated by addition of zinc dust and the solution again filtered and concentrated.  A table summarises the results obtained by digestion of dried blood as above with oxides of lead, zinc, cadmium, mercury, cobalt, nickel and copper and thallium hydroxide.  The compositions, when stabilised and admixed with water and a gas, will produce foams suitable for extinguishing fires.  Specification 601,956 is referred to.  The Specification as open to inspection under Sect. 91 describes foam-generating agents obtained by the hydrolysis of any sulphur-containing proteinaceous material by means of the above-mentioned metal oxides or hydroxides, in the presence of an aqueous medium at a temperature between 105 DEG and 200 DEG  C.  This subject-matter does not appear in the Specification as accepted.