Nylon 6 fabric dyeing generally uses anionic dyes (acid dyes, mordant dyes, direct dyes and reactive dyes), and disperse dyes can also be used. At present, most nylon 6 fabrics are dyed with acid dyes, but there are problems such as color, strip and fixing cost when dyeing. With the increasing emphasis on environmental protection, higher requirements have been placed on the dyeing process of nylon 6 fabrics. Therefore, it is of great significance to develop new high-performance dyes or clean dyeing processes.
Disperse dye microcapsules use microcapsule technology to coat conventional pure disperse dyes into fine particles. With the excellent sustained release function of microcapsules, the dye dyeing rate can be effectively controlled. Therefore, level dyeing can be achieved without leveling agent. effect. In addition, the wall of the microcapsule has a certain isolation function, which can prevent the dye particles or the concentrated solution of the dye from directly contacting the fabric, avoiding the stain formation, and thus eliminating the need for adding a dispersing agent. The use of disperse dye microcapsule dyeing not only eliminates the addition of auxiliaries, but more importantly, it can fundamentally eliminate the COD, BOD load caused by the auxiliaries, and the serious chromatic contamination caused by the solubilization of the auxiliaries. After dyeing, the dyeing wastewater contains only microcapsule particles, which can be reused or filtered, and can be reused or directly discharged to achieve clean dyeing.
In this experiment, nylon 6 fabric was dyed with disperse dye microcapsules, and the optimal dyeing process parameters were determined by orthogonal test to explore the clean dyeing production of nylon 6 fabric.
1 test
1.1 Drug Disperse Blue 56 Microcapsule Dyes (Hans Chemical), Weak Acidic Blue Blue Rawl (Zhangzhou Xinghua Chemical), special test soap tablets (Shanghai Soap Factory).
1.2 Fabric Nylon 6 fabric (60g/m2), standard viscose lining and standard polyamide lining (Shanghai Textile Industry Technology Supervision Institute).
1.3 Instrument high temperature and high pressure dyeing machine (Taiwan Ruby), 72 type spectrophotometer (Shanghai Precision Scientific Instrument Co., Ltd.), SF6 (X) color measuring color meter (American Datacolor company), soaping fastness machine (Roaches, UK) , ATI people SCM a type 5 dry and wet machine (US SDLATI Sheng 5 company)
1.4 Test methods
14.1 Orthogonal test uses bath ratio, holding time and dyeing temperature as the three influencing factors, each factor takes five levels, and the factors and levels are formulated (see Table 1).

1.4.2 Nylon 6 fabric Conventional acid dyeing process Conventional dyeing of nylon 6 fabric is carried out using weak acid brilliant blue Rawl. The process curve is as follows:

1.5 Test methods
1.5.1 Determination of K/S value of dyed fabric The /KS value of the dyed sample was determined using an SF 600 colorimetric colorimeter.
1.5.2 Determination of color fastness of dyed fabrics. Determination of stain fastness and soaping fastness. Refer to GB/T3912.1-1997 "Color fastness to wash fastness of textiles test";
For the determination of rubbing fastness, refer to GB/T3902-1979 "Color fastness to rubbing of textile color fastness test".
2 Results and discussion
2.1 Analysis of influencing factors According to Table 1, the L25 (5th power of 3rd) orthogonal table was designed to test the K/S value (â–³E) of the dyed fabric under different processes, and the range R was calculated, as shown in Table 2.
It can be seen from Table 2 that among the three factors of the nylon 6 fabric disperse dye microcapsule dyeing process, the most significant effect is the temperature, the holding time is second, and the bath ratio has the least influence.
2.2 Determination of dye bath ratio As can be seen from Table 2, when the bath ratio is 1:01, 1:02, â–³E>0.1, indicating that the fabric leveling property is general; when the bath ratio is 1:30, 1:40, 1:50 When â–³E<0.1, it indicates that the levelness of the fabric is good at this time. Therefore, the test bath ratio is set to 1:30.
2.3 Effect of dyeing temperature on dyeing effect The effect of dyeing temperature on fabric dyeing effect is shown in Table 3.

In Table 3, nylon 6 fabrics exhibited excellent rubbing fastness, soaping fastness and color fastness on the viscose (both grades above 4) under various dyeing temperature conditions. As the dyeing temperature increases, the color fastness of the brocade decreases sharply. Especially at the dyeing temperature of 110 °C, the color fastness of the nylon 6 fabric is 1 to 2, which may be due to the color of the disperse dye microcapsules. Deep sake.
In addition, as the dyeing temperature increases, the dyeing depth of nylon 6 fabric gradually increases, and the dyeing depth increases sharply at 80-100 °C, and the growth potential slows down after 100 °C. The dyeing temperature of the fabric is preferably 100 °C.
2.4 Effect of holding time on dyeing effect The effect of holding time on the color fastness and dyeing effect of dyed fabrics is shown in Table 4.

It can be seen from Table 4 that the holding time has little effect on the color fastness of nylon 6 fabric, but when the holding time is 40 min, the wet and dry rubbing fastness of the fabric can be increased by half.
The holding time has a moderate effect on the /KS value of the disperse dye microcapsule dyed nylon 6. The general trend is that the dyeing depth gradually increases with time. The fabric holding time is most suitable for 40 minutes.
2.5 Determination of the optimum process for the dyeing of fabric disperse dye microcapsules According to the above test, the optimum dyeing temperature curve of nylon 6 fabric disperse dye microcapsules is determined as follows:

2.6 Comparison with traditional acid dyeing process

In Table 5, the dry/wet rubbing fastness of the microcapsule-dyed nylon 6 fabric was used, and the soaping fastness and the color fastness of the 40 °C were both in the 4-5 grade, which was comparable to the conventional acid dye-dyed nylon 6 fabric. However, the former has a lower density than the traditional acid dyeing method. This may be because the microencapsulated disperse dye is darker than conventional dyeing; it may also be that the disperse dye is different from the acid dye on the nylon 6 fabric: the former relies mainly on van der Waals force and hydrogen bonding on the nylon 6 fabric, while the latter mainly The dye anion is ionically bonded to the terminal amino group ionized by the nylon 6 fiber.
In addition, it can be seen from Table 5 that the absorbance of the disperse dye microcapsule dyeing residue is much smaller than that of the conventional acid dye residue, and the dye residue is substantially clear and transparent, and the chroma is very low. No reduction cleaning or addition of additives is required in the dyeing. In theory, the COD and BOD values ​​of the dyeing wastewater are also low. Therefore, after the wastewater is allowed to stand or filtered, the recycling of the dyeing wastewater can be basically achieved.
3 Conclusion
(1) In the nylon 6 fabric disperse dye microcapsule dyeing process, the temperature has the greatest influence, the holding time is second, and the bath ratio has the least influence. The optimum process parameters are: bath ratio 1:30, 10 °C for 40 min, and isolation microcapsules for 20 min.
(2) Dry/wet rubbing fastness of dyeing of nylon 6 fabric disperse dye microcapsules, soaping fastness at 40 °C and color fastness to sticking are basically the same as those of traditional acid dyeing methods, all at level 4-5; The color fastness of the brocade is slightly lower than about 1 level; at the same dye concentration, the dyed fabric of the disperse dye microcapsules has a darker color than the conventional dyeing.
(3) The absorbance of the nylon 6 fabric disperse dye microcapsule dyeing residue is smaller than that of the traditional acid dye residue, and the chroma value of the dyeing wastewater is low. Since the reduction process is not required during the dyeing process, and no additives are added, the CoD and BOD values ​​of the dyeing wastewater are theoretically low.

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