Reactive emerald blue dye has a relatively large molecular weight and poor solubility, permeability and diffusivity. When mixing the material, it needs to be beaten with cold water and then diluted with hot water. If the amount of dye is too much, Urea can be added to help dissolve. During the dyeing process, the adsorption rate of active emerald blue is higher than the diffusion rate, which will cause excessive adhesion of the dye to the fiber surface, which may easily cause color flowers, color spots, serious floating color, and poor fastness during production.
Therefore, during operation, it is necessary to strictly implement the process requirements and frequently check the product quality of each process.
Dyeing production practice
Process flow: pre-treatment → dyeing → soaping → color fixation → soft.
Pre-treatment
Cotton fiber contains waxy substances and nitrogen-containing Substances, minerals, cotton seed shell pigments, etc., especially carded cotton yarn spun from inferior cotton, contains more impurities, as well as oil and dirt contaminated during the spinning process. These impurities will affect the pre-treatment wool effect of cotton knitted fabrics and reduce The wettability of the fabric hinders the dyeing process, resulting in uneven dyeing, dim color, and reduced color fastness.
The purpose of pre-treatment is to remove impurities on the yarn, ensure the whiteness and wool effect of the cotton fiber, and provide a good foundation for dyeing.
The whiteness and wool effect of cotton knitted fabrics boiled and bleached are directly related to the leveling, permeability, and lifting properties of dyeing on reactive emerald blue. Therefore, before dyeing cotton with reactive turquoise, it must be cooked and bleached. After pre-treatment, the cotton knitted fabric must have a clean surface, uniform whiteness, consistent pH value, and good wool effect to ensure the quality requirements of the next process of dyeing.
The water used for pre-treatment and dyeing should be soft water, because the calcium, magnesium, and iron ions in hard water will react with alkali to produce calcium and magnesium salt precipitation, and will react with the water-soluble radicals in active emerald blue during dyeing. The clumps react to form some precipitates. These insoluble substances will adhere to the surface of the fabric or yarn, affecting the dyeing and finishing process and the quality of the finished product. Therefore, soft water must be used in pre-treatment and subsequent dyeing processes.
Process example: (g/l)
Chelating dispersant 0.5～2.0
Hydrogen peroxide stabilizer 1.0～1.5
Soda ash 3.0～5.0
Degreaser 1.0～2.0
Hydrogen peroxide 3.0～4.0
Liquor ratio 1:8
Note: After boiling and bleaching, it must be rinsed cleanly and passed through a stream of hot water to remove the remaining oxygen from the dye liquor and knitted fabric, so as not to affect the dyeing of the fiber. You can also rinse it once. Add deoxygenase, run for 20 minutes, measure the oxygen content, and then OK to stain directly.
Staining
Reactive Emerald Blue Its molecular weight is large and it lacks linear structure, so its solubility, diffusivity and permeability are poor. Care should be taken during operation. The dye must be fully dissolved before being added to the dye vat. Add salt and alkali in batches. When reactive turquoise dyes cotton, it is first adsorbed on the fiber surface through van der Waals forces or hydrogen bonds, and diffuses into the fiber. Then it reacts with the fiber under alkaline conditions to form a covalent bond and is fixed on the fiber.
Reactive emerald blue has weak reactivity and low dye uptake rate. When reacting with fiber, it also undergoes hydrolysis reaction to generate hydrolyzed dye. This hydrolyzed dye has very little affinity with fiber and mainly displays adsorption. After dyeing, the dry and wet rubbing fastness is low, and the leveling effect is not ideal. Therefore, after dyeing, the hydrolyzed dyes and unreacted dyes attached to the fiber surface must be washed away with soap. In production, an appropriate amount of reactive dye leveling agent should be added to emerald blue or emerald green to improve leveling and color-light stability.
The influence of Yuanming powder on dyeing
Yuanming powder is Electrolyte acts as a dye accelerator when dyeing cotton with active emerald blue. It can change the dyeing speed and dyeing rate. A small amount is added, and the dye utilization rate is low. A large amount is added, and the dyeing time can be shortened, but it is not easy to dye evenly or evenly. Transparent and easy to produce colored flowers. Reactive emerald blue is less sensitive to electrolytes (compared to other reactive dyes). When the content of Yuanming powder in the dyeing solution is less than 30g/L, the dyeing promotion effect is more obvious. As the content increases, the dyeing promotion effect is very weak. When the amount of starch powder locally reaches 250g/l, the dye will agglomerate and salt out. In actual operation, the method of pre-adding starch powder and soda ash (or baking soda) can be used, that is, first add 1~5g/l of starch powder/ L and soda ash 0.5~1g/L are added into the auxiliary tank to fully dissolve and then poured into the main tank. After running for ten minutes, add the dye. This method can improve the dyeing rate of reactive emerald blue (a small amount of alkali will increase the hydroxyl group on the cellulose. Negative ion conversion rate), and dye utilization rate.
When dyeing dark emerald blue, if you need to add a larger amount of Yuanming powder or soda ash, pay special attention to the aggregation and salting out phenomenon caused by excessive local content.
The influence of soda ash on dyeing
Reactive dyes in alkaline conditions It reacts with cellulose fibers, which is a color-fixing reaction. In factory production, soda ash can be added in batches according to the depth of the color to slowly increase the pH value of the dye solution. When the pH value is greater than 10, reactive emerald blue is very sensitive. Always pay attention when dyeing.
When adding soda ash, it should also be added in batches: add 10% for the first time, use the reflux dye liquor to dilute with a large bath ratio, and add 10% for the second and third times.Use a certain amount of hydrated material for three times. Beat it into a slurry first and then dilute it with hot water (60~80℃). After thinning, pump it from the auxiliary tank into the main tank. The amount of soda ash added should be determined according to the amount of dye. If it is too low, the Dyeing is not thorough, the addition amount is too large, and the reaction is too fast. Although the dyeing amount has increased to a certain extent, it is easy to produce color flowers, color difference and dye agglomeration. At the same time, the hydrolysis of the dye is also accelerated. When color matching emerald blue and bright yellow, it is not easy to use the method of pre-adding alkali, because bright yellow is more sensitive to alkali, dyes quickly, and is prone to color blooming problems.
The effect of temperature and time on dyeing
Reactive emerald blue dyeing When the time comes, you can add materials at room temperature, add alkali to fix the color, and then raise the temperature to 60°C for dyeing. It can also be dyed at high temperature (85~90℃) and then cooled down (70℃) and added with alkali fixation process. The specific process can be determined according to the factory’s own conditions.
Process formula: (g/l)
Chelating dispersant 0.5～2.0
Leveling agent Vast 0.5～1.5
Active emerald blue % X
Yuanming powder 10～70
Soda ash 4～20
Liquor ratio 1:6～8
Process curve ：
The hardness of the dyeing water should be low, and soft water should be used for dyeing. The phthalocyanine molecules of active emerald blue will combine with calcium and magnesium ions in the water or other heavy metal ions in the water, affecting product quality.
Active leveling agent has a solubilizing effect, which can effectively prevent the aggregation of emerald blue in the dye liquor and reduce the occurrence of color flowers and color spots.
Soaping (boiled alkali)
The purpose of soaping is Wash away the dyes, hydrolyzed dyes, etc. that are adsorbed on the surface of the yarn and are not combined with the fiber. The soaping effect directly affects the wet processing fastness of the product. Therefore, when soaping, you must use a soaping agent with a better soaping effect. The washing time should ensure that soaping is thorough, and the soaping agent selected should have the characteristics of resistance to hard water and soaping under neutral and weak acid conditions.
High-temperature alkaline conditions during soaping will partially break the ether bond formed by the combination of active turquoise blue and fiber. After the ether bond is broken, the solubility of its parent is very low, and it is more difficult to clean the fiber surface. , will cause problems such as color spots and low color fastness. Medium to dark colors can be soaped twice and then fixed. Recommended soaping conditions are: 90°C × 15-20 minutes, pH value around 6, not alkaline, temperature not too high, as too high will affect product fastness.
Color fixation
The purpose of color fixation is to improve the color of the fabric Fastness, improve product quality and grade; use high-fastness color fixing agent t to fix the color of soaped emerald blue or color matching products, which can improve the color fastness by about 1 level.
Process example:
Color fixing agent (o.w.f) 1.0～2.
Glacial acetic acid (g/l) 0.3～0.5 (adjusted pH value 5.5～6)
Temperature/℃ 45～50
Time/min 20
Softening treatment
Pre-warping of fabric After processing, dyeing, and feeling rough and hard, it needs to be softened and finished to improve the feel and resilience of the product, giving the fabric excellent softness, smoothness, and comfortable wearing properties. There are many types of softeners, and hydrophilic and smooth silicone oil can be used to meet people’s higher quality requirements for clothing.
One of the most worrying things when using silicone-containing softeners in dyeing factories is the occurrence of silicone spots. Special attention should be paid to the operation during the production process to avoid losses. At the same time, the selected soft oil or hydrophilic silicone oil has less impact on the color of the product.
The selected hydrophilic silicone oil must have the advantages of alkali resistance, high temperature resistance, no silicon spots, non-stick to the cylinder, and can be directly dissolved in cold water. In the factory production process, in order to avoid defects in the finished product, two processes of softening are generally required. One is to apply soft oil in the dye vat, because silicone oil in the dye vat can easily produce silicon spots; the other is to apply silicone oil in the rolling groove of the setting machine.
Dyeing vat with soft oil:
Soft oil 5﹪
Time 15～20min
PH value 5.0～6.0
Glacial acetic acid g/l 0.3～0.5 (PH value, 5.0～5.5)
Temperature and time 45℃×20min
The shaping machine is passed through the rolling groove with silicone oil: hydrophilic, soft and smooth silicone oil 20~30g/l.
Notes
1. Pre-processing requires uniformity. Use soft water, because the iron and copper ions in hard water will promote the decomposition of H2O2. Under high temperature and strong alkali conditions, the fibers will be seriously degraded, and incompatible calcium and magnesium soaps will easily form and adhere to the fabric.
2. Fully dissolve the dye to prevent the dye from aggregating in the dye liquor. When combining reactive turquoise blue and reactive bright yellow, it is not easy to add alkali in advance, or add Yuanming powder and soda ash at the same time, otherwise it will Causes dye aggregation and precipitation (bright yellow is sensitive to alkali), causing product quality problems.
3. Yuanming powder and soda ash should be added in multiple times to prevent salting out and dye hydrolysis, and at the same time, it can also reduce color flowers and color difference.
4. Rinse well before over-softening and adjust the PH value. The softener should be diluted first and then added slowly. The various surfactants selected must be compatible; otherwise, it will be difficult to wash. The substance adheres to the surface of the fabric.
5. Always check whether there are sticky objects in the vat, and if so, remove them in time; otherwise, during dyeing, these substances will partially separate from the dye vat and contaminate the fabric.
6. Knitted fabrics dyed with turquoise blue cannot be parked. The next process is carried out immediately. After the post-processing is completed, drying and shaping are carried out immediately. Because if the wet cloth is left for a long time, the fibers will absorb the air. Acidic gases (such as sulfur dioxide, etc.) are then used to replace the copper ions in the turquoise molecules, resulting in a wind mark phenomenon. The lighter the color, the more obvious the wind mark phenomenon is.
If the wet cloth is left for a long time, the fiber will absorb acidic gases in the air (such as sulfur dioxide, etc.), and then replace the copper ions in the turquoise molecules, resulting in wind marks. The lighter the color, the more obvious the wind marks will be.
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