Abstract: A melamine.melam.melem salt of a polyphosphoric acid, which has a solubility of from 0.01 to 0.10 g/100 ml in water (25.degree. C.), a pH of from 4.0 to 7.0 as a 10 wt % aqueous slurry (25.degree. C.), and a melamine content of from 0.05 to 1.00 mol, a melam content of from 0.30 to 0.60 mol and a melem content of from 0.05 to 0.80 mol, per mol of the phosphorous atom; andA process for producing the above mentioned melamine.melam.melem salt of a polyphosphoric acid, which comprises the following steps (a) and (b):(a) a step of obtaining a reaction product by mixing melamine and phosphoric acid at a temperature of from 0 to 330.degree. C. in such a ratio that the melamine is from 2.0 to 4.0 mols per mol of the phosphoric acid (as calculated as orthophosphoric acid content), and(b) a step of baking the reaction product obtained in step (a) at a temperature of from 340 to 450.degree. C. for from 0.1 to 30 hours.

Abstract: A 1,3,5-triazine derivative salt of a polyacid comprising phosphorus, sulfur and oxygen, which has a solubility of from 0.01 to 0.10 g/100 ml in water (25.degree. C.) and a pH of from 2.0 to 7.0 as a 10 wt % aqueous slurry (25.degree. C.), and which is obtained from the following steps (a) and (b):(a) a step of obtaining a reaction product by mixing melamine, phosphoric acid and sulfuric acid at a temperature of from 0 to 330.degree. C. in such ratios that the melamine is from 1.0 to 4.0 mols per mol of the total molar amount of the phosphoric acid (as calculated as orthophosphoric acid content) and the sulfuric acid (as sulfuric acid content), and the sulfuric acid (as sulfuric acid content) is from 0.05 to 20 mols per mol of the phosphoric acid (as calculated as orthophosphoric acid content), and(b) a step of baking the reaction product obtained in step (a) at a temperature of from 340 to 400.degree. C. for from 0.1 to 30 hours; and a process for its production.

Abstract: A melamine polymetaphosphate having a solubility of from 0.01 to 0.10 g/100 ml in water at 25.degree. C., a pH of from 2.5 to 4.5 in the form of a 10 wt % aqueous slurry at 25.degree. C. and a melamine content of from 1.0 to 1.1 mol per mol of phosphorus atom.A process for producing such a melamine polymetaphosphate, which comprises the following steps (a) and (b):(a) a step of mixing melamine, urea and an aqueous orthophosphoric acid solution containing at least 40 wt % of orthophosphoric acid, in such a ratio that melamine is from 1.0 to 1.5 mol per mol of orthophosphoric acid and urea is from 0.1 to 1.5 mol per mol of orthophosphoric acid, at a temperature of from 0 to 140.degree. C., to form a reaction mixture, and stirring the reaction mixture at a temperature of from 0 to 140.degree. C., while removing water, to obtain a powdery product of a double salt of orthophosphoric acid with melamine and urea; and(b) a step of calcining the powdery product obtained in step (a) at a temperature of from 240 to 340.

Abstract: A melamine cyanurate powder composed of readily dispersible aggregated primary particles of melamine cyanurate surface-treated with a metal oxide.

Abstract: An apparatus for laminating plates having guide holes for aligning each plate to a predetermined position. A horizontal base is provided for stacking the plates thereon. A conveyor device conveys the plates to a predetermined position over the horizontal base one by one, the conveyor device dropping the plates on the horizontal base from the predetermined position so as to laminate the plates to each other. A guide device including guide pins which are disposed perpendicular to the conveyed plate at the predetermined position above the conveying device, the guide pins moving together with the falling plate to engage in the guide holes, respectively, to align each of the plates along the guide pins while laminating the plate on the horizontal base, and to return the guide pins to the initial position thereof.

Abstract: The present invention provides a power flame retardant for a halogen-containing vinyl resin, which comprises the following Components A, B and C. (A) 5 to 30 parts by weight of at least one of alkali metal compound of lithium, sodium and potassium calculated as the formula M.sub.2 O where M is an alkali metal; (B) 0.2 to 10 parts by weight of a perchloric acid radical in the form of the acid or a salt or amine thereof, calculated as perchloric acid radical; and (C) 1 to 50 parts by weight of a hydrophobic dispersing agent having a boiling point or a decomposition temperature of 200.degree. C. or higher. All the parts by weight are based on 100 parts by weight of antimony pentoxide (Sb.sub.2 O.sub.5). The flame retardant of the present invention does not impair transparency of the halogen-containing vinyl resin, and also does not worsen various physical properties such as thermal stability and weathering resistance.