Abstract: The present invention provides a process for separating and purifying alkali metal salts of hydroxynaphthalenecarboxylic acids, in which alkali metal salt(s) of hydroxynaphthalenecarboxylic acid(s) are separated and purified from a mixture of alkali metal salts of hydroxynaphthalenecarboxylic acids by treating it with a nonionic porous synthetic adsorbent using water or water and water-soluble organic solvent(s).

Abstract: A coating apparatus comprises a head (25) having opposite edges (6, 7) cooperating with each other to provide an outlet (4a) of a coating liquid supply slit (4), and opposing portions (23a, 23b) between which a longitudinal recess (28) is formed, and a plurality of adjusting devices (30) having opposite ends (31, 32) engaged with the opposing portions of the head. A pulling or compressive force is developed between the opposite ends of each adjusting device so as to adjust the clearance (D) of the opposite edges. The adjusting means are movable in the longitudinal direction of the apparatus with their ends being engaged with the opposing portions of the head.

Abstract: The present invention provides a method for effectively separating independent hydroxynaphthalene-carboxylic acids by treating a mixture containing various kinds of hydroxynaphthalene-carboxylic acids with nonionic porous synthetic adsorbents having as a basic structure aromatic copolymers mainly composed of styrene and divinyl benzene or methacryl copolymers mainly composed of monomethacrylates and dimethacrylates.