Abstract: A flame-retardant electrolytic solution of an electrolyte salt in an organic solvent, wherein the organic solvent contains at least one phosphorus compound represented by formula (I) and a nonaqueous secondary battery containing the flame-retardant electrolytic solution. wherein R1 represents an alkyl group having 1 to 8 carbon atoms, a halogenated alkyl group, an aryl group, an alkylaryl group, an aralkyl group or —CH2—COOR3; R2 represents a methyl group, an ethyl group or a halogenated alkyl group having 1 to 8 carbon atoms; R3 represents an alkyl group having 1 to 8 carbon atoms or a halogenated alkyl group; and m and n each represents 1 or 2 and the sum of m and n is 3.

Abstract: Acridine compounds such as 1,4-butylenebis-.beta.-(acridin-9-yl)acrylate, or the like, are high in light sensitivity and suitable as a photopolymerization initiator.

Abstract: A substituted acridine derivative represented by ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently hydrogen atoms, alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, halogen atoms, or alkoxy groups, and Z.sub.1 is a six-membered heteroaromatic group which has one or two nitrogen atoms in its ring and may have an alkyl substituent having 1 to 8 carbon atoms, or a quinolyl group; and a photopolymerizable composition comprising 0.01 to 10 parts by weight of said derivative, 100 parts by weight of a photopolymerizable compound having a boiling point of 100.degree. C. or higher at atmospheric pressure and at least one kind of ethylenic unsaturated group, and 0 to 400 parts by weight of a thermoplastic organic polymer.

Abstract: Acridine compounds such as 1,4-butylene-bis-.beta.-(acridin-9-yl)acrylate, or the like are high in light sensitivity and suitable as a photopolymerization initiator.