Abstract: Disclosed is a red phosphorus flame retardant comprising a fine red phosphorus powder subjected to a surface modification treatment, said fine red phosphorus powder consisting of spherical red phosphorus particles and/or agglomerates thereof directly obtained by the thermal conversion of white phosphorus in the presence of a dispersant and has an average particle size of 10 .mu.m or smaller and of which at least 80% by weight is accounted for by particles having particle sizes of 20 .mu.m or smaller, said flame retardant having an average particle size of 15 .mu.m or smaller, with the particles having particle sizes of 35 .mu.m or smaller accounting for at least 80% by weight of the flame retardant; and a nonflammable resinous composition composed of a synthetic resin and the red phosphorus flame retardant.

Abstract: High purity alkali metal hypophosphites are produced in high efficiency by a simple step of using no other separating agents than white phosphorus, alkali metal hydroxides and water as reaction raw materials, resulting in no need of a complicated procedure for removing impurities.

Abstract: Red phosphorus flame retardants for synthetic resin are produced by a method comprising the steps of heating yellow phosphorus at temperatures of 250.degree. to 600.degree. C. to effect a partial conversion of yellow phosphorus to red phosphorus; removing unconverted yellow phosphorus; and coating particles of the resulting red phosphorus with at least one of thermosetting resin and metal hydroxide. The thus obtained red phosphorus flame retardants are very stable because of significantly improved heat resistance, water resistance and weatherability and thus can provide nonflammable resinous compositions which can be used for long period of time. The nonflammable composition consists essentially of 100 parts by weight of polyolefine resin, 20 to 200 parts by weight of hydrated inorganic filler and 0.1 to 30 parts by weight of the coated red phosphorus flame retardant.

Abstract: A flame retardant comprising of spherical red phosphorus free of pulverized face which is directly produced in the form of fine powder by conversion of yellow phosphorus, without pulverizing process. The red phosphorus characterized by its surface state and shape entirely different from any prior pulverized red phosphorus has not only a high flame retarding ability, but also a superior combination of chemical and physical properties, particularly with regard to corrosion resistance, moisture resistance, mechanical strength and dielectric properties which make it highly valuable and useful as a flame retardant for various nonflammable resinous compositions used in electric articles including electronic parts, machines, automobiles and buildings. The flame retardant is desirably coated with thermosetting rein and/or hydroxide of aluminum and/or zinc, thereby greatly improved in its stability.

Abstract: A flame retardant comprising of spherical red phosphorus free of pulverized face which is directly produced in the form of fine powder by conversion of yellow phosphorus, without pulverizing process. The red phosphorus characterized by its surface state and shape entirely different from any prior pulverized red phosphorus has not only a high flame retarding ability, but also a superior combination of chemical and physical properties, particularly with regard to corrosion resistance, moisture resistance, mechanical strength and dielectric properties which make it highly valuable and useful as a flame retardant for various nonflammable resinous compositions used in electric articles including electronic parts, machines, automobiles and buildings. The flame retardant is desirably coated with thermosetting resin and/or hydroxide of aluminum and/or zinc, thereby greatly improved in its stability.