Optical film and method for manufacturing same, polarization plate, and liquid crystal display apparatus

An optical film including a thermoplastic resin,

• wherein the optical film has a moisture permeability of 70 g/m2/day or less, and
• contains a moisture permeability-reducing compound having a molecular weight of 200 or more and satisfying Formula (1) described below,
• wherein the moisture permeability-reducing compound is a compound represented by General Formula (B) described below, a phenolic resin represented by General Formula (C) described below, a terpene resin, an aromatic hydrocarbon formaldehyde resin, or barbituric acid;
• A/B≤9 Formula (1)
• in Formula (1), A represents a moisture permeability of an optical film in a case in which 10 mass % of the moisture permeability-reducing compound is added to the mass of the thermoplastic resin, B represents a moisture permeability of an optical film in a case in which the thermoplastic resin is included and the moisture permeability-reducing compound is not added,
• with the proviso that the moisture permeability is a moisture permeability in terms of a film thickness of 40 μm of the optical film after 24 hours at 40° C. under a relative humidity of 90% using a method of JIS Z-0208,
• in General Formula (B), each of R12, R13, R14, R15, R16, R21, R23, R24, R25, R32, R33, R34, R35, and R36 independently represents a hydrogen atom or a substituent, and at least one of R12, R13, R14, R15, R16, R21, R23, R24, R25, R32, R33, R34, R35, and R36 is an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a hydroxyl group, a mercapto group, or a carboxyl group, and
• in General Formula (C), n represents 1 to 10, each of ms independently represents an integer of 1 to 4, each of Rs independently represents a hydrogen atom, a —OH group, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, at least one of Rs represents a group having a —OH group, and each of L1 and L2 independently represents a methylene group or —CH2—O—CH2—.