Powdery emulsifier for oil-based drilling fluid

The invention relates to a powdery emulsifier for an oil-based drilling fluid and belongs to the technical field of oil field drilling fluid treatment agent synthesis. 2,6-diaminopyridine, COOH-(CH2)b-COOH diacid, NH2-(CH2)a-NH2 diamine and CH3(CH2)c-COOH aliphatic acid are mixed according to a mole ratio of 1: 2: 2: 1, a reaction temperature is in a range of 140-150 DEG C, time of each one of three copolymerization reactions is in a range of 3-5h, and the product is crushed to form the powdery emulsifier at a normal temperature. Through hydrogen bond interaction of groups, the solid emulsifier with a strong inner action force and an aggregation structure is formed. The powdery emulsifier is solid powder at a temperature of 0-120 DEG C, has a strong emulsification capability, resists a temperature of 180 DEG C, can be easily packaged and transported, can be operated easily on site and well satisfies on-site construction requirements.