Introduction to sodium chlorate-yellow blood salt discharge printing process for indigo denim
Introduction to sodium chlorate-yellow blood salt discharge printing process for indigo denim
【Abstract】The oxidation discharge agent composed of sodium chlorate (main extraction agent), yellow blood salt (oxygen conductor) and citric acid (catalyst) can be used in the white discharge or color discharge printing process of indigo dyed cloth, as long as it is heat treated With proper temperature and time control, satisfactory discharge printing effects can be obtained.
【Key words】Indigo denim; discharge printing; sodium chlorate; yellow blood salt
[Chinese Library Classification Number] TS194·452 Document Identification Code: B Article Number: 1005-9350 (2006) 10-0018-03
Over a hundred years since the United States began producing jeans in the 19th century, jeans have gradually become sexual clothing. With the recovery of the printed fabric market, indigo denim discharge printing production has developed rapidly in recent years. It develops towards diversification in appearance, with different effects and styles, opening up a new path for the denim series.
As we all know, indigo dye is very difficult to discharge, and reduced indigo powder and whitening agent W are usually used as indigo discharge agents for discharge printing. This process is used to extract white and slightly yellow color. If the vat dye which is resistant to extraction is used as the color extraction, the process is complicated and the cost is high. But it does not damage the strength of the fabric.
According to the structure and properties of indigo dye, in addition to reducing agents, the chemical action of oxidants can also be used to split the conjugated double bonds in the indigo dye structure to achieve the purpose of discharge printing. The reaction is as follows:
At present, commercial dye discharge agents still belong to the category of oxidative dye discharge agents. Because of their high price, printing costs are high. In order to reduce the printing cost, according to my many years of printing work experience and verification by production, indigo oxidation discharge printing can choose the commonly used chemical sodium chlorate as the main body of oxidation discharge, and use yellow blood (sodium) salt as the base of sodium chlorate. Oxygen-conducting agent uses citric acid as a catalyst for oxidative discharge. The dye discharge slurry is prepared according to a reasonable proportion. The operation is simple and fast, the steaming time is short, and the dye discharge quality is excellent. It can be compared with commercial dye discharge agents. The fabric strength retention rate is as high as over 90%, and the cost of the dye discharge composition is only It is about 1/5 of commercial dye discharge agent and has good economic benefits.
1Sodium chlorate-yellow blood (sodium) salt discharge printing process
1·1 Process flow
Indigo denim → pre-printing treatment → printing → drying (105℃) → steaming (100-101℃, 8-1Omin) → baking (130-135℃, 2-4min) → washing → drying.
1.2 Pre-printing treatment
The warp yarns of indigo denim are made from raw yarns that are first moistened with a solution of caustic soda and penetrant; then immersed in indigo dye solution and oxidized, repeated 6-8 times; washed with water after dyeing, and an appropriate amount of softener is added to the last washing tank. , to facilitate the dispersion and drying of yarn bundles during warping; and then sizing to facilitate weaving. The weft yarn is just made of raw yarn. When denim is washed, in order to improve the feel and increase the fullness and smoothness of the cloth, it is treated with light sizing to increase the cloth weight and stiffness. Therefore, denim contains impurities such as cellulose symbionts, indigo float, caustic soda, and slurry. In order to improve the printing effect and paint color fastness, desizing is necessary.
(1) Enzyme desizing by flat washing machine: first wash four compartments with hot water at 70-80℃
(Pre-washing to remove caustic soda)→Desizing (7658 amylase 3-5g/L, salt 5-8g/L, penetrant JFC 2-3g/L, pH value 6-7, temperature 55-60℃)→Stacking ( About 5Omin, temperature 55-60℃) → wash in hot water for four steps (above 95℃) → wash in cold water → dry.
(2) Enzyme desizing of jigger dyeing machine: Wash the upper shaft with hot water (50-60℃) → Enzyme desizing (7658 amylase 1.2kg/150L, salt 0.5kg/150L, penetrating agent JFCO.5kg/15OL, pH value 5.5 , temperature 55-60℃, 30min) → hot water wash (90-95℃, four passes) → cold water wash two passes → upper shaft → drying.
After desizing the denim, the requirements are: ① Clean desizing; ② The fabric is neutral; ③ Capillary effect (3Omin) 8cm.
2 Composition and preparation of dye discharge paste
2.1 Composition of dye discharge paste
Prescription (%): White discharge paste Paint coloring discharge paste
Sodium chlorate 10 9
Yellow blood (sodium) salt 4 3.6
Citric acid 6 5.4
Urea 5 5
Acid-resistant original paste \ ]
Paint x
Adhesives y
2·2 Preparation
Take an appropriate amount of acid-resistant raw paste at room temperature, and under stirring conditions, add the ingredients in the following order: ① urea; ② yellow blood (sodium) salt; ③ sodium chlorate; ④ citric acid. When adding materials, sprinkle slowly and wait until it is dissolved before proceeding to the next feeding sequence. It is advisable to add citric acid before using the discharge paste. The preparation of color drawing paste is the same as direct printing with paint. The viscosity of the dye discharge paste should be controlled at 50-6OdPa·s.
3 Sodium chlorate-yellow blood (sodium) salt dye discharge paste
3·1 sodium chlorate
Sodium chlorate is the main component of oxidative discharge. The optimal amount of sodium chlorate should be selected based on the depth of indigo color, printed fabric, printing area, pulp supply amount, overprinting and other conditions. Insufficient dosage will affect the discharge effect, while excessive dosage will not help discharge but will increase the damage to the fabric.
3.2 Yellow blood (sodium) salt
It is required to complete the steaming process in just a few minutes.Printing paste, prepared at room temperature, is simple and fast, has low dosage, stable quality, short steaming time, controllable process conditions, and excellent discharge effect, which is comparable to commercial discharge agents, and the printing cost is only that of commercial discharge agents. l/5 or so, the economic benefits are very significant.
The key to sodium chlorate-yellow blood (sodium) salt discharge printing is the correct control of temperature and time during heat treatment, which can take into account high-quality discharge printing, and the strong retention rate is as high as over 90%. 7dhrBMDx
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