METHOD FOR PRODUCING LIQUID COMPOSITION

An object of the present invention is to provide a method capable of producing, with high productivity, a liquid composition that does not cause uneven coating or nozzle clogging and that does not contain eluted substances that cause a decrease in luminance lifetime. The present invention relates to a method for producing a liquid composition comprising a phosphorescent material and an organic solvent, the method comprising the steps of: dissolving a phosphorescent material in an organic solvent to prepare a mixed liquid, and filtering the mixed liquid obtained in the above step by a filtering device; wherein the filtering device comprises a housing or holder, a fluororesin membrane filter, and a filter support member; a material of a portion of the housing and holder, the portion being in contact with the mixed liquid, is a metal alone or a mixture of a metal and at least one member selected from the group consisting of glass, fluororesins, polyethylene not containing a phosphorus antioxidant, and polyethylene not containing an oxidized phosphorus antioxidant; and a material of a portion of the filter support member, the portion being in contact with the mixed liquid, is at least one member selected from the group consisting of metals, glass, fluororesins, polyethylene not containing a phosphorus antioxidant, and polyethylene not containing an oxidized phosphorus antioxidant.