What should I do if color spots and stains appear in reactive dyeing?

Reactive dyes have a very good solubility in water.Reactive dyes mainly rely on the sulfonic acid group on the dye molecule to dissolve in water. -Ethylsulfonyl sulfate is also a very good dissolving group In the aqueous solution, the sodium ion on the sulfoethylsulfone sulfate group undergoes hydration reaction, so that the dye becomes anion and dissolves in the water. The dyeing of reactive dyes is dyed to the fiber by the negative ion of the dye. The solubility of reactive dyes is more than 100 g/L, most of the dyes have a solubility of 200~400 g/L, and some dyes can even reach 450 g/L. However, during the dyeing process, the solubility of the dye will decrease due to various reasons (or even completely insoluble). When the solubility of the dye decreases, part of the dye will change from a single free anion to particles, due to the large charge repulsion between the particles. Decrease, the particles and particles will attract each other to produce agglomeration. This agglomeration firstly gathers the dye particles into agglomerates, then turns into agglomerates, and finally turns into flocs. Although the flocs are a kind of loose assembly, because of their There is an electric double layer formed by positive and negative charges around it. Generally, the shear force of the dye liquor is difficult to decompose it, and the flocs are easy to precipitate on the fabric, resulting in surface dyeing or staining. Once the dye has such agglomeration, the fastness of dyeing will be significantly reduced, and at the same time it will cause different degrees of stains, stains, and stains. For some dyes, the flocculation will further accelerate the assembly under the shear force of the dye solution, causing dehydration and salting out. Once salting out occurs, the dyed color will become extremely light, or even not dyed, even if it is dyed, there will be serious color stains and stains. Causes of dye agglomeration The main reason is the electrolyte. In the dyeing process, the main electrolyte is the dye accelerant (yuanming powder and salt). The dye accelerant contains sodium ions, and the equivalent number of sodium ions in the dye molecule is much lower than the dye accelerant. In the normal dyeing process, the concentration of the normal dye accelerant will not have much influence on the solubility of the dye in the dye bath. However, when the amount of dye accelerant increases, the concentration of sodium ions in the solution also increases accordingly. Excess sodium ions will inhibit the ionization of sodium ions on the dissolving group of the dye molecule, thereby reducing the solubility of the dye. When the concentration of the dye accelerating agent exceeds After 200 g/L, most dyes will undergo different degrees of aggregation. When the concentration of the dye accelerator exceeds 250 g/L, the degree of aggregation will increase. Aggregates and flocs are formed quickly. Some dyes with low solubility will be partially salted out, or even dehydrated. The anti-agglomeration and salt-out resistance properties of dyes with different molecular structures are also different. The lower the solubility, the anti-agglomeration and resistance The poorer the salting out performance. The solubility of the dye mainly depends on the number of sulfonic acid groups in the dye molecule and the number of β-ethylsulfone sulfates. At the same time, the greater the hydrophilicity of the dye molecule, the higher the solubility, the lower the hydrophilicity, and the solubility The lower (for example, the hydrophilicity of the dye with the azo structure is higher than the dye with the heterocyclic structure). In addition, the larger the molecular structure of the dye, the lower the solubility, and the smaller the molecular structure, the higher the solubility. Solubility of reactive dyes It can be roughly divided into four categories Class A, dyes containing diethylsulfone sulfate (i.e. vinylsulfone) and three-reactive groups (monochloros-triazine + divinylsulfone) have the highest solubility, such as Yuan Qing B, Navy Blue GG, Navy Blue RGB, Golden RNL and All reactive blacks made by mixing Yuanqing B, three-reaction group dyes such as ED type, Ciba s type, etc. The solubility of these dyes is mostly around 400 g liters. Class B, dyes containing heterobireactive groups (-chloros-triazine+vinylsulfone), such as yellow 3RS, red 3BS, red 6B, red GWF, RR three primary colors, RGB three primary colors, etc., and their solubility is 200-300 g The solubility of meta-ester is higher than that of para-ester. Class C: Navy blue that is also a heterobireactive group: BF, Navy blue 3GF, dark blue 2GFN, red RBN, red F2B, etc., due to less sulfonic acid groups or larger molecular weight, its solubility is also low, only 100~200 g/ Rise. Class D: Dyes with monovinylsulfone group and heterocyclic structure, with the lowest solubility, such as brilliant blue KN-R, turquoise blue G, bright yellow 4GL, violet 5R, blue BRF, brilliant ora

Confirmation of textile color samples and solutions to common problems

Color sample confirmation 1. Self-evaluation of color samples Use gray cards to match colors. Level 4.5 is required between the original sample and the sample sample. When using a measuring and matching instrument for color matching, generally ∆E<1, taking into account the system error, the internal control standard ∆E<0.6, strive for a standard sample. For high requirements, hue ∆H and saturation ∆C should also be taken into consideration. To fully understand the heat sensitivity and photosensitivity of the dye. There are few photosensitive dyes, such as try not to use Cibacron Yellow CR-01, especially Cibacron Yellow C-2R. Most dyes have more or less heat sensitivity. Shihlin dyes are more prominent. Cold, hot, dry and wet have an impact on the shade. When proofing such dyes, consider the tendency of the dye to stabilize after the dye, and intentionally reverse it. Deviate a bit. For example, most dyes tend to be slightly darker to red light after they are stabilized, and when the color is slightly cold after printing, they should be slightly greenish light so that the color light is just equal to the original when it is stable. Dyes with severe photosensitivity and heat sensitivity are used as the main color proofing, which may cause large-scale production of color cloth stacking and printing, and even irreversible in severe cases, such as olive green R, yellow C-2R and other dyes. Therefore, such dyes cannot be used. Whether the prototype meets the customer's requirements, we must know how to make a sample for regular customers, and it is easy to match the customer's habits. Different regions have different color preferences. For example, European orders avoid red and can be slightly greenish. Different consumer groups of fabrics have different color and light bias. For example, children's clothing generally likes to be gorgeous; men's clothing should try to be neutral, with low color saturation and dark gray; women's clothing should be bright and so on. General customers require at least 3 prototypes, namely A, B, C samples, and sometimes 12 samples. Consider from the aspect of depth, light and shade, bright and bright, and color, so as to improve the accuracy of the first time. 2. Recognition of the sample When the customer's opinion differs from the actual situation, the light source should be considered and communicate with the customer. When the customer reports that most of the samples in a color palette are too dark, it should be considered that the customer may have a double-layer counterpart, especially for thin and transparent fabrics, which will become darker when stacked. Some large companies require 4 layers of color matching for thin and transparent woven fabrics and knitted fabrics. The conventional is a single-layer contrast. When the "light jumping" is serious, consider replacing the dye to improve the "light jumping". To understand the "metamer" performance of dyes, make full use of colorimeters to screen dyes. When the dyestuffs applied by our factory cannot meet the customer's "jumping light" requirement or the "jumping light" is ∆E<0.5, we should communicate with the customer to confirm the sample of our factory. When the confirmed sample is used as the reference sample, there is no "jumping". Light" problem. Never choose a dye formulation that is unstable in mass production to meet customer requirements. When directly producing samples for color matching, you should try to match the colors under various light sources, such as D65 natural light, fluorescent lamps, and do not have serious "jumping lights". If it is serious, please confirm before production. 3. Confirmation of production of large sample (head cylinder sample) The color and light requirements for the production of large samples should be strictly in accordance with the customer's approval opinions, and the original sample should be used as the basis to confirm the deviation. It is best to persuade the customer to use the confirmed sample as the basis to deviation from the original sample. Because the fabric specifications of the confirmed sample are consistent with the large sample, it is easy to see the sample, the dyes used are the same, and there is no "light jumping" phenomenon. Generally, the color light is between the two, the gray card reaches 4 or more, ∆E<1 (the internal control standard is generally ∆E<0.8), and customers will recognize it. The batch difference is controlled above level 4 of the gray card, the left, middle and right color difference is controlled above level 4 to 5, and the batch difference ∆E<1 (within 0.8 of the internal control). When selecting dyes, try to use dyes consistent with the sample prescription. Adjust the color and light, the newly added dyes may cause the phenomenon of "bounce light". When there is an obvious "bounce light" between the large sample and the confirmed sample, there will be the risk of rejection of the large product, which will bring economic loss and