The invention discloses a
fiber penetrating swelling agent which comprises the compositions in weight portion: 0.00016 to 0.0006 portion of
laurocapram, 1 to 5 portions of N-methyl pyrrolidone, 5 to 10 portions of
diacetone alcohol, 5 to 15 portions of
ethyl salicylate, and 5 to 10 portions of
isopropyl salicylate. The invention also discloses a method for
dyeing by the
fiber penetrating swelling agent, comprising the following steps that: a
reducing agent and
sodium hydrate are used for reducing the dye by a vatting method; the weight ratio of a reducing solution to the dye is 37.5: 0.8 to 2.0; a leveling agent and the
fiber penetrating swelling agent are added to dye or a
buffering agent is added to adjust the pH value and is dyed by vat acid, the temperature is reduced and the mixture is washed; the mixture is subjected to oxidizing to develop color, fixing, reducing temperature and washing; the
fresh water bath is performed, the fiber penetrating swelling agent is reduced and washed, and the temperature is reduced and the fiber penetrating swelling agent is produced. The fiber penetrating swelling agent ensures that the dye insoluble in water is effectively moistened and penetrated, and the fiber crystallizing area is effectively swelled to receive the dye; the fiber penetrating swelling agent ensures that a suspended
solid is dyed evenly, has good homochromatism, improves the degree of
dyeing, and solves the 'white core' problem of fiber.