The former is generally dyed polyester / wool and polyester / nitrile and other blended fabrics, and can not be high temperature and high pressure dyeing the small batch of tape and clothing supplies, the key to dyeing is to choose no carcinogenic substances; no organic chlorine and odor, easy to clean with Plasticization of the carrier;
The latter mostly adopts high-temperature and high-pressure jet overflow dyeing machines, warp beam dyeing machines, and cross-dyeing machines (horizontal-opening type). The skein yarns and tube yarns are mostly dyed by cage-type, barrel-type, and hanging-type circulating flow machines.
Common staining disorders are as follows:
1. Color flowers (dyeing)
In addition to the above-mentioned contaminant-removing machine factors, it is generally caused by a defective dyeing process, which is a manifestation of uneven distribution of dyes in dye baths. In order to prevent coloration, for the dyeing machine, firstly, the flow circulation pump should have sufficient force, the seal should be good, the heat exchanger should be unblocked, and in short, the dynamic balance must be achieved; followed by the thermometer, pressure gauge, pressure relief valve, and computer control device. Must be complete and the process is reasonable (see Table 1).
2. Color stains (spots)
(1) Some stains (spots) are caused by the high temperature of the material, and are even more pronounced when the water hardness is high. In order to avoid dye aggregation, the water temperature of dissolving the disperse dyes can be 30-40°C, and the water hardness is preferably 100-150 mg/kg. Practice has confirmed that if the water hardness is too high, even if it is dissolved in advance and is filtered and then added to the dye bath, it will re-aggregate, resulting in a color point. Therefore, the quality and temperature of the material must be taken seriously.
(2) The dye itself has poor diffusivity, dispersibility, and high temperature dispersion stability. The fillers (diffusion agent MF, lignin sulphonate) are of poor quality, and in particular, the tar content in the diffusing agent is high, resulting in poor dispersibility. In addition, the ratio of diffusing agent and lignin is not proper, and although the former is also resistant to high temperatures, it is the latter that actually produces a stable effect under high temperature conditions. In this case, an appropriate amount of polyester dye repair agent or high-efficiency dispersant may be added during dyeing to prevent secondary agglomeration during the dyeing process, promote the emulsification and dispersion of tar-like substances, and cause it to dissolve into the dye liquor. Stain the fabric again and finally wash it off.
(3) The quality of polyester varies. If the pretreatment is not proper, the oligomers on the fibers cannot be completely removed. It is easy to fall off under high temperature and high pressure conditions, and coagulate with the dye. Alkali-reduced polyester fabrics basically do not have this phenomenon.
(4) When the dyeing machine is added, the dyeing solution is too concentrated, the dilution is not enough, the speed is too fast, the initial dyeing temperature is too high, and the amount of cloth is large, which is also a factor that cannot be ignored in the formation of dyeing defects.
3. stained
This rickets is mainly manifested in the dyeing of a variety of fiber blended fabrics.
Practice has confirmed that other dyes have little coloration on polyester, while disperse dyes have almost all stains on other fibers. To reduce stains, we must first deal with the dyeing water, so that the metal and earth metal ions in the water can be effectively chelated, reduce the interference of normal dyeing, and with sufficient washing, can effectively overcome the stain. Second, we must pay attention to the use of dyes and additives. For the dyeing of a variety of fiber mixed fabrics, it is necessary to calculate the cost, but also to choose a good process, such as a one-bath one-step, one-bath two-step and two-bath processing process, if necessary, can add 2-3g/L anti-stick Agents to reduce mutual staining and improve color fastness. Finally, cleaning and reduction cleaning are important steps to remove floating color and impurities on the fiber. Alkali (NaOH) and reducing agent (Na2S2O4) are usually used, but the effect is not good, because they will partially break the hydrolysis of azo and ethyl acetate groups in the molecular structure of some disperse dyes, increasing the water content. Bathing chemicals contaminate each other to reduce the effect of washing.
4. Color change
In a sense, the degree of discoloration is actually a manifestation of the fastness of disperse dyes.
To overcome this phenomenon, the following points should be emphasized in the application:
(1) The compatibility of each dye in the prescription is better.
For the more sensitive green-gray series, especially yellow and blue, the heat stability needs to be consistent, and sometimes it is often necessary to add a little red color. The three dyes cannot use the three primary colors with high, middle and low temperature inconsistencies. It is better to choose a secondary color, with little color change and good reproducibility. It is not possible to use two high-temperature dyes as the main color, and add a low-temperature dye as the secondary color. Otherwise, after the heat setting, the color light will have more obvious changes.
(2) The heat setting temperature must be adjusted according to the variety and dyestuff used, and strictly controlled.
Most processes increase the heat setting temperature above 200°C and the speed is 50m/min or more. As a result, the width of the width of the fabric after heat setting was not controlled, and sometimes it was found that the color difference between before and after heat setting was large, which was due to sublimation (gasification) of the dye with poor heat resistance. Therefore, the heat setting temperature is controlled at 180-190°C×200-25m/min to effectively prevent the color change phenomenon.
(3) Insulation dyeing time and after dyeing cleaning are all related to the color change.
It must be pointed out that solvent-based auxiliaries, such as silicone microemulsions and carriers, cannot be used in the formulation and finishing processes, otherwise disperse dyes on the fibers will evaporate with the solvent during heat treatment at 200°C (above). At the same time, gasification eventually leads to discoloration. According to the solid solution theory of disperse dyestuff polyester, the post-treatment temperature of dyed polyester is much higher than the dyeing temperature, and the dye inside the fiber will migrate outwards. To prevent discoloration, post-processing (heat setting) temperatures are also important.
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