The invention discloses a
chromium-free tanning agent in the tanning industry and a synthetic production process thereof; the formula (weight ratio) comprises: 60-150 parts of
amide containing
hydroxymethyl, 30-100 parts of aliphatic aldehydes, and 1-5 parts of anti-yellowing agent. The production method comprises the following steps: in the first step, 60-150 parts of
amide containing
hydroxymethyl are added into a reaction kettle with a stirring function, a
thermometer, a
reflux condenser and a
vacuum distillation unit; in the second step, temperature is raised to 30 to 40 DEG C; in the third step, 30-100 parts of aliphatic aldehydes are dripped; in the fourth step, 1-5 parts of anti-yellowing agent are added with 2-4 hours of heat insulation; and in the fifth step, decompression
distillation is carried out for 4-6h at the temperature of 50-90 DEG C and the pressure of -0.3bar-0.95bar for removing the water. The third step and the fourth step can be exchanged. The invention solves the color changing problem in the production and storage processes of the products, adds a small amount of anti-yellowing material
alkali metal and the borate solution of
alkaline earth metal, greatly improves the storage conditions of the '
oxazolidine' type tanning agent, and prolongs the quality guaranteeing time; as the anti-yellowing material has low price, is easy for acquisition, and has small adding amount, the invention does not affect the application characteristics of the products and can be widely promoted.