An environmentally-friendly processing method for dyeing denim fabric with zero discharge, comprising:
- step 1, a treatment of white warp yarns, including sub-steps of selecting white warp yarns, sewing edges of the white warp yarns using a sewing machine, removing thread residues, spreading out and placing the treated warp yarns in a Teflon drying barrel, increasing the temperature inside the drying barrel with a high-temperature steam for 10-15 min, turning off heating to let the warp yarns to cool, then placing the cooled warp yarns in a plasma barrel, and performing plasma drying treatment on surfaces of the warp yarns at normal pressure for 10-15 min, and obtaining a pre-processed material A;
- step 2, a primary drying operation, including sub-steps of placing and spreading out the pre-processed material A in an drying chamber, increasing the temperature inside the drying chamber to a high operation temperature within the range of 135-150° C. first, maintaining the temperature for 30 min, then decreasing the temperature inside the drying chamber to a temperature within the range of 45-55° C., maintaining the temperature for 10 min, then turning off heating, and after the heated material gets cool, obtaining a processed material B;
- step 3, a coating spray-dyeing operation, including sub-steps of placing and spreading out the processed material B in a spray-dyeing chamber, loading a spray-dyeing solvent, increasing the temperature inside the spray-dyeing chamber to a temperature within the range of 65-75° C., maintaining the temperature for 10 min, then turning off heating, performing spray-dyeing operation, and obtaining a semi-finished product C;
- step 4, a secondary drying operation, including sub-steps of placing and spreading out the semi-finished product C on a bearing panel in the drying chamber, increasing the temperature inside the drying chamber to a temperature within the range of 170-190° C., maintaining the temperature for 10 min, decreasing the temperature inside the drying chamber to a temperature within the range of 50-55° C., maintaining the temperature for 5 min, and after the material gets cool, obtaining a semi-finished product D;
- step 5, a sizing operation, including sub-steps of loading a prepared sizing solution onto a sizing machine, spreading out the semi-finished product D on the sizing machine, performing sizing operation at a yarn speed of 30 m/min and a tank temperature of over 95° C., and obtaining a semi-finished product E after the sizing operation is completed;
- step 6, a ternary drying operation, including sub-steps of placing and spreading out the semi-finished product E on the bearing panel in the drying chamber, increasing the temperature inside the drying chamber to a temperature within the range of 130-150° C., maintaining the temperature for 5 min, continuously decreasing the temperature of the drying chamber to the temperature of 60° C., maintaining the temperature for 10 min, turning off heating after a size film is formed on the surfaces of the warp yarns, and after the heated material gets cool, obtaining a pre-fabricated product F;
- step 7, a doffing operation, including sub-steps of uniformly spraying a softening agent on the surface of the denim fabric, performing doffing operation at a lathe speed of 40 m/min and a heating temperature within the range of 130˜150° C. and under a pressure within the range of 10˜12 MPa, and after the shape of the fabric is fixed, obtaining a finished product G.