Vegetable dye one-bath dyeing method for polyester and cotton blended yarns

The invention discloses a vegetable dye one-bath dyeing method for polyester and cotton blended yarns, and relates to the technical field of yarn dyeing. The method comprises the following steps of firstly pre-treating yarns, extracting natural vegetable dye by a supercritical CO2 extraction method, putting the yarns into a cylinder, adding clear water and the vegetable dye according to a bath ratio of 1: 10, adding a penetrant, a dispersant and formic acid, heating to 50 DEG C, adding anhydrous sodium sulphate, continuously raising the temperature to 85 DEG C, keeping the temperature for 40 minutes, and performing drainage and washing; adding neutral soap flakes, raising the temperature to 45 DEG C at the speed of 2 DEG C/min, keeping the temperature for 20 minutes, adding sodium carbonate, keeping the temperature for 10 minutes, and performing drainage and washing; and finally, adding a color fixing agent, heating to 60 DEG C, keeping the temperature for 20 minutes, and performing drainage and washing to fi