Flame-retardant resin film and solar battery back sheet using the same

A flame-retardant resin film obtained from a resin composition,

• wherein the resin composition comprises (a) a polyphenylene ether resin or a mixture consisting of 30 to 99.9% by mass of a polyphenylene ether resin and 70 to 0.1% by mass of a polystyrene resin, (b) a phosphorus flame retardant, and (c) a fluorine-containing resin,
• the polyphenylene ether resin contains a bonding unit represented by the following formula (1):
• (wherein R1, R2, R3, and R4 each are selected form the group consisting of hydrogen, halogen, a primary or secondary lower alkyl group having 1 to 7 carbon atoms, a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbon oxy group, and a halohydrocarbon oxy group in which a halogen atom and an oxygen atom are separated by at least two carbon atoms, and may be the same or different from each other),
• in the resin composition, a content of the component (a) is 75 to 98 parts by mass and a content of the component (b) is 25 to 2 parts by mass, based on 100 parts by mass of the components (a) and (b) in total,
• a content of a fluorine element in the resin composition is 100 to 1000 mass ppm, and
• the flame-retardant resin film has a thickness of 20 to 500 μm.