4-hydroxybenzoic acid is a widely used organic synthetic raw material, especially its esters, including methylparaben (nepoline), ethyl ester (interpret), propyl ester, butyl ester, isopropyl ester. , isobutyl ester, can be used as food additives, used in soy sauce, vinegar, refreshing drinks (except soda), fruit flavorings, fruits and vegetables, pickled products, etc., also widely used in food, cosmetics, medicine, antisepsis, mildew Agents and fungicides. Hydroxybenzoic acid is also used as an intermediate in dyes and pesticides. Used in the synthesis of organophosphorus insecticides GYAP, CYP in pesticides; color developer for the synthesis of heat-sensitive dyes in the dye industry; also used in color film and synthetic oil-soluble coupler "538" and nylon 12 The raw material for the production of plasticizers. In addition, it is also used in liquid crystal polymers and plastics.