Learning Points│General Quality Problems of Knit Fabric Dyeing and Selection of Additives【Product Practice Application】

The color fastnesses are light fastness, soaping fastness, perspiration fastness, rubbing fastness, sublimation fastness, ironing fastness, etc. The key to these fastnesses lies in the structural properties of dyes, but also with the fiber, dye concentration, Dyeing and finishing processes and external conditions are closely related, so whether the color fastness is up to standard, the key is to select dyes, followed by dyeing process and the application of additives.

When the dyeing process is formulated, it must be reasonably determined according to dyes, fibers, and customer specifications, so that the dyes can be dyed as firmly as possible under certain conditions with the help of the additives, so that the fibers are fully fixed. For the additives, they are selected. A good leveling agent and an accelerating agent allow the dye to be dyed slowly, evenly and fully. The second is the addition of a chelating agent to overcome the complexation of dyes with water metal ions to form a floating color, and to reduce the hydrolysis of active dyes in water; The third is to choose excellent soap lotion, to the net floating color, and prevent floating color re-contamination fabrics; Fourth, select the appropriate fixing agent, the current sublimation fastness, sun fastness, etc. is not yet ideal fixing agent , For the soaping fastness, perspiration fastness, rubbing fastness and other indicators have excellent fixing agent can be selected.

2 crisp

Brittleness is manifested as a strong decline. In addition to the reasons such as pre-processing due to oxygen bleaching and other processes causing brittle or even broken holes and other reasons, the brittleness caused by the dyeing stage generally has two reasons, one is the photosensitive brittle caused by such a dye such as sulfur black Damage, need to use anti-brittle agent to improve, there are strong reducing agents such as vat dyeing and strong oxidants on the fiber's brittle; Second, the dyeing stage or neutralization stage of improper use of acid, neutralization of acid is generally used glacial acetic acid , While the market currently supplies some substitute acids, these substitute acids have organic buffer acids like BASF, do not contain strong inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and even better performance than acetic acid. These buffer acids can also improve the ice. Some disadvantages of acetic acid (such as glacial acetic acid in winter use inconvenience, stimulating taste, residual acidity, and the combination of metal ions (such as Ca2 +, Mg2 +) in the water left on the fabric caused by shading, etc.). Some alternative acids containing H2S04, HCl, H3P04, etc., not only cause the shade change, but also have a corrosive effect on the dyeing and finishing equipment and the pump, and the acid residue after neutralization can also cause the fabrics to be brittle under acidic conditions.

3 Wrinkles

The main reasons are due to equipment, there are reasons for the amount of cloth, bath ratio reasons and processing operations and other reasons, the equipment is different as a pipe load, the pressure and friction between the cloth and cloth, pump force and strength All affect the fabric fabric flatness, the bath ratio will also affect the fabric flatness, too many auxiliary foam in the process of operation caused on the fabric floating method and process operations in the temperature and cooling phenomenon of quenching and sudden fever will result in fine Wrinkle phenomenon. The current wrinkle-reducing agent in the bath, bath in the treasure, softener in the bath can improve the fine wrinkle phenomenon, but if the equipment does not improve, the process control is not good, the lubricant alone can not completely avoid the thin wrinkle produced.

4 Wind prints

The relationship between printing and additives is not significant, the key is the performance of the dye itself (acid and alkali resistance) and the fabric with acid and alkaline, air humidity and sour gas and so on, such as the direct dye in the sun Cuilan GC, frozen yellow G and other acid gas is easy to produce Fengyin, active Cuilan KN-G, brilliant orange X-GN and other sensitive to acid and alkali are also easy to produce Fengyin, disperse dyes such as yellow RGFL sensitive to alkali, but also easy to produce Fengyin For auxiliaries, the neutralization must be done so that the surface of the fabric is as high as PH = 7. Therefore, attention must be paid to the acid and alkali species at the time of neutralization, and the acid should use glacial acetic acid or organic substitute acid as much as possible. In the case of alternative acids containing strong inorganic acids such as H2SO4, HCl, the choice of base should also be as mild as possible."

5 color flowers (including color, color, etc.)

Color flowers are the most common and most common quality problems in the dyeing process. The reasons are:

1 Process development and operation issues:

Insufficient procedural or improper operation to produce color flowers;

2 Equipment issues:

Such as disperse dyes dyed polyester after heat setting machine oven temperature is not easy to produce color difference color flower, rope dyeing machine pump power is also easy to cause color flowers and so on.

3 Dye problems:

Dyes are easy to aggregate, have poor solubility, poor compatibility, and are susceptible to temperature and pH. Such as active Tsui Lan KN-R is easy to produce color flowers.

4 Water quality issues:

Poor water quality results in the combination of dyes with metal ions or the aggregation of dyes and impurities to cause coloration, and light colored colors are not attached.

5 Additives:

For the auxiliary problem, the color-related additives include penetrants, leveling agents, chelating dispersants, and PH control agents. Penetrant penetrating power is not enough, easy to cause uneven dyeing fluid and color, such as loose cotton dyeing, cheese yarn dyeing, heavy fabric dyeing, penetrant agent can not be ignored, some plant penetrant only believe authentic JFC, but Without considering that the cloud point of the JFC is only 38-42°C, and it exceeds 42°C, the penetrating power of the JFC will not be exerted and will cause quality problems. Leveling agents are used for polyester, cotton, wool nylon, acrylic used in various types of leveling agent, uneven quality, levelling agent must take into account the dispersion of the dye to help dissolve the role of slow dyeing and migration, to help infiltration Even the complexation of metal ions in the water, and must take into account the pH applicability, foam and other factors affect the color rate, etc., leveling agent to improve the color flower, color point and other phenomena are indelible, and some The levelling agent in the factory is only a solution of the diffusing agent N, but it is not thought that the diffusing agent N has a greatly reduced resistance to dye agglomeration at high temperatures. Some plants choose non-ionic surfactants to be unsuitable, resulting in the precipitation of non-ionic surfactants above the cloud point, and the adsorption of dyes to form tar-like substances on the fabric equipment, causing quality problems. The quality of the chelating dispersant is also related to the leveling problem. At present, under the condition that the water quality is getting worse, the chelating dispersant should pay more attention to the level dyeing. The problem of PH control is a problem not taken seriously by all plants. The pH of dyeing per cylinder is not the same in some plants, and the quality of substitute acid used in some plants is different. For example, phosphoric acid and phosphoric acid generated by three-stage ionization There are differences, how can we control the PH value of the uniform? Some plants use PH slip, but do not grasp the relationship between temperature and time and the PH value of the slippery, PH control can not be discussed, so the color, Chromatic aberration continues to occur.

6 color dots (including white dots)

There are many reasons for the color point, such as the white point, which may be the reason why the non-mature cotton is not dyed, or it may be due to the fact that soda ash and other solids are stained on the cloth to cause no local dyeing. The main reason for the color point is:

1 Improper dye selection: Dye particles are too large or easy to produce agglomerated color points;

2 Poorly dissolved dye: undissolved dye enters the dyeing point on the fabric;

3 Poor water quality: Dye condensation caused by poor water quality:

4 The equipment is not clean: the color point is caused by the tar under the dyeing tank;

5 Auxiliary reasons: Adding auxiliaries during dyeing sometimes causes the dye to agglutinate and produce color spots; too much foam for the auxiliary agent, the foam and the dye combine into a colored foam to stain the fabric to form a color point; On fabrics and equipment, the aggregates on the equipment will turn to the fabric to cause color spots.