1. Dyeing principle:
Sulfur dyes are insoluble in water, but can be reduced by sulfide alkali to form sodium salts Leucobody and dissolved in aqueous solution. This leuco body has strong directness to fibers in alkaline solution, so it can be adsorbed by fibers. After oxidation, the dye changes back to an insoluble state and is deposited on the fibers.
2. Experimental steps:
1. Experimental materials and instruments
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Fabric: cotton knitted fabric
Dye: sulfur dye
Auxiliary: flake alkali sulfide (NA2S) , baking soda (NaHCO3), pure water, CP-5 soaping agent
Instruments: CNC water bath, electronic balance, purified water, dyeing machine, dyeing cup, oven
2. Experimental method
① Chemical materials and weighing cloth
Weighing cloth: weigh 5g of cotton knitted fabric per portion;
Seal the mouth of the bottle with plastic wrap; put it into a CNC water bath, stir and keep warm at 92°C for 20 minutes.
②Dye pipetting and placing into cloth
Dyeing conditions:
Non-black (o.w.f): 1.0 %3.0%
Black (o.w.f): 3.0%6.0%
Liquor ratio: 1:20
Baking soda (NAHCO3): 6g/L
According to the above dye dosage, select pipettes with different capacities, rinse the pipette and the inner wall of the bottle, transfer the required dye solution and add it for dyeing Cup, add pure water and baking soda, put a cloth on it, and tighten the lid to seal.
③ Enter the tank and heat up the dyeing
Put the dyeing cup into the dyeing machine, set the heating rate to 1.5℃/min, and raise the temperature to 100 Dye at ℃ for 60 minutes.
④Soaping method
Soaping conditions:
Liquor ratio: 1:20
Temperature and time: 98℃×10min
Soaping agent: 2.0g/L
After dyeing is completed, Take out the dyeing cup, cool it down directly, and wash it with water. Leave the cloth to oxidize in the air for 10 minutes. Then put the oxidized cloth into the dyeing cup, add 100mL of prepared soaping agent (2.0g/L), and seal it. Put it into the dyeing machine, set the heating rate to 5.5°C/min, raise the temperature to 98°C and keep it for 10 minutes.
⑤Finishing method
After soaping is completed, take out the steel cup, directly cool down, wash and dry, put the cloth in the oven, and dry it. Dry.
⑥Computerized color measurement method
Adopt the color matching system and calibration system. Use the color matching system to measure the color at 4 points of the dyeing sample and obtain the average data. , determine DL*, Da*, Db*, CMC DE* and weighted intensity.
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