Patent GB-874587-A (GB)
Title: Manufacture of azodicarbonamide
IPC: C08J9/10
Filed: 1958-10-14
Abstract: Azodicarbonamide H2NCON : NCONH2 prepared by the oxidation of hydrazodicarbonamide (see Group IV(b)) is used as a blowing agent for rubber and plastics.  In examples, rubber compositions containing styrene-butadiene rubber, styrene-butadieneresin, cumarone-indene resin, stearic acid, octylated diphenylamine, hydrated silica, hard or soft clay, ground whiting, titanium dioxide, zinc oxide, and light process oil, with or without diethylene glycol and pentachlorothiophenol or its zinc derivative are mixed with azodicarbonamide, dibenzothiazyl disulphide, diorthotolylguanidine and sulphur, with or without diethyleneglycol, and the compositions cured.  In similar compositions, the polymeric materials are styrene-butadiene rubber and cumaroneindene resin; and styrene-butadiene resin, styrenebutadiene rubber, pale crepe and cumaroneindene resin.  In the last case, the composition was finally cured with a mixture of azodicarbonamide, sulphur and tetramethylthiuram di-sulphide.ALSO:Azodicarbonamide H2NCON : NCONH2 is prepared by suspending one part by weight of hydrazodicarbonamide in 2-4 parts by weight of water to form an aqueous slurry, adding to the slurry CrO3 in the presence of a mineral acid or an alkali metal chromate in the presence of a mineral acid ("mineral acid" being defined as an acid with a mineral base which reacts with an alkali metal chromate to produce CrO3), the amount of CrO3 being at least sufficient to effect complete oxidation of the hydrazodicarbonamide to azodicarbonamide; and ensuring that the temperature of the reaction mixture does not exceed 85 DEG F. until all the reactants have been added and before conversion to azodicarbonamide has commenced.  The reaction mixture may then be maintained at not above 150 DEG F. until approximately complete conversion is attained.  In variations of the process, reaction may be carried out completely at 32 DEG F.; or 5-30% conversion is allowed to take place at 32 DEG F. followed by heating to not above 150 DEG F.; or 30% conversion is allowed to take place at 50, 65 or 80 DEG F., followed by heating to not above 150 DEG F.; or up to 80% conversion is allowed to take place at below 85 DEG F., followed by heating to not above 150 DEG F. Specified mineral acids are sulphuric and phosphoric acids. "Chromate" includes dichromate and polychromate. Hydrazodicarbonamide is prepared by the reaction of urea with hydrazine or its salts, e.g. the sulphate  Azodicarbonamide is used as a blowing agent in rubber and plastics (see Groups IV(a) and V).ALSO:Azodicarbonamide H2NCON: NCONH2 prepared by the oxidation of hydrazodicarbonamide (see Group IV(b)) is used as a blowing agent for rubber and plastics.  In examples, rubber compositions containing styrenebutadiene rubber, styrene-butadiene resin, cumarone-indene resin, stearic acid, octylated diphenylamine, hydrated silica, hard or soft clay, ground whiting, titanium dioxide zinc oxide, and light process oil, with or without diethylene glycol and pentachlorothiophenol or its zinc derivative are mixed with azodicarbonamide, dibenzothiazyl disulphide, diorthotolylguanidine and sulphur, with or without diethyleneglycol, and the compositions cured.  In similar compositions, the polymeric materials are styrene-butadiene rubber and cumarone-indene resin; and styrene-butadiene resin, styrene-butadiene rubber, pale crepe and cumarone-indene resin.  In the last case, the composition was finally cured with a mixture of azodicarbonamide, sulphur and tetramethylthiuram disulphide.