Foreword: High alkali-resistant disperse dyes are not only suitable for dyeing polyester under weak acidic conditions, but also suitable for dyeing polyester under neutral and alkaline conditions. The process execution process is to combine the pre-treatment and Dyeing is carried out in one bath.
Taking polyester nylon coral velvet as an example, the process parameters and operating points of polyester microfiber dyeing, fiber opening, alkali reduction and other processes under highly alkaline conditions are given. This process greatly shortens the process flow and saves time, thereby achieving the goals of energy saving, emission reduction, production cost reduction, and reducing environmental pollution. After testing, color fastness, color light and other indicators all meet the requirements, and it is a new process worthy of praise.
Dyeing and high alkali resistance dispersion of traditional polyester
Polyester is a type of synthetic fiber that is widely used at present. For many years, polyester has been dyed using the traditional process of high temperature and high pressure dyeing under weakly acidic conditions. For polyester materials that require high alkali treatment, the process has many steps, a long process, large consumption of water, electricity, and steam, low production efficiency, high production costs, and large sewage emissions, which aggravates the degree of environmental pollution and also Increased burden of wastewater treatment.
Dyeing polyester with highly alkali-resistant disperse dyes can overcome these shortcomings. Penglai Jiaxin Dyestuff Chemical Co., Ltd. has been committed to the research of highly alkali-resistant disperse dyes in recent years. It has produced and developed a set of highly alkali-resistant disperse dyes composed of more than a dozen colors such as yellow, magenta, blue, and dark blue. It can be used at pH Polyester is dyed within the range of =4.5~14.0. Since it can withstand 10g/L strong alkali and 6g/L hydrogen peroxide, it can be used in various dyeing processes of many polyester fabrics. This study takes polyurethane coral velvet as an example to discuss the dyeing process of highly alkali-resistant disperse dyes.
General dyeing process of polyester coral velvet
Polyester coral velvet The dyeing and finishing process of velvet fabrics (generally polyester-nylon mass ratio 80:20) generally adopts the process of first opening the fibers in alkaline conditions, reducing the weight in alkali conditions, then washing and neutralizing them, and then dyeing polyester in acidic conditions.
The dyeing and finishing process is as follows: rough cloth → unwinding → seam → pre-shaping → alkali reduction (fiber opening) → water washing → acid washing and neutralization → high temperature and high pressure dyeing → Restorative cleaning → washing → neutralization → softening → dehydration → drying → nap → carding → shearing → (shake) → tenter setting → finishing.
1. Pre-shaping
Processing of polyester and coral velvet, Pre-shaping is a key process. After alkali reduction (fiber opening) and dyeing of rough fabrics without pre-shaping, the coral silk will be bent and irregular, and cannot achieve the style of coral velvet. After pre-shaping, the coral yarns are neatly arranged, straight and fluffy, and the bottom yarn structure is tight and stable, making it difficult to curl during subsequent dyeing and finishing processes.
The general temperature for the pre-shaping of coral fleece gray fabric is 165~90℃. The time depends on the vehicle speed, and the tension is enough to make the fabric flat.
2. Alkali weight reduction (fiber opening)
In printing and dyeing In the factory, liquid alkali (generally 30% liquid alkali dosage is 5-8 g/L, the dosage can also be converted with caustic soda) is used for alkali reduction (fiber opening) to dissolve the water-soluble polyester in the polyester fiber. The polyester/nylon fiber strands originally bonded together are scattered and fluffy, becoming polyester/nylon ultrafine fiber monofilament bundles [2]. It is then washed with water and neutralized with acid to make the cloth surface free of alkali and neutral or weakly acidic, which is conducive to acid dyeing under high temperature and high pressure conditions in the subsequent process. During the above-mentioned dyeing and finishing process, the fiber weight reduction rate is approximately 5.0% to 6.0%. An insufficient weight reduction rate will affect the hand feel, and a too large weight reduction rate will destroy the fiber structure of the fabric and affect the strength. It is necessary to find out the reasonable amount of alkali to use through experiments and formulate reasonable process conditions to ensure that the weight reduction rate is within a stable and normal range and cannot exceed 7% to 8%.
The dyeing and finishing process consumes a large amount of water, glacial acetic acid, electricity, and steam. It also discharges a large amount of alkaline sewage, which virtually increases production costs.
Alkali reduction formula:
Degreasing penetrating agent EPD 1.0g/L, 30% NaOH 10.0g/L , reduction accelerator 1.0~1.5g/L, liquor ratio 1:15~1:20, temperature 130℃, time 20~30 minutes.
The amount and time of alkali solution are determined according to the weight loss rate required by the customer, and must be tested beforehand; the liquor ratio is appropriately selected according to different equipment. Some printing and dyeing factories use a temperature of 98°C and a time of 60 minutes or a temperature of 110°C and a time of 40 minutes for fiber opening. The process formula must be adjusted accordingly according to the actual situation.
3. High temperature and high pressure dyeing process
After alkali reduction Polyester dyeing of coral velvet is carried out under the condition of pH=4.5~5.0. Since the polyester and nylon microfibers have a large specific surface area and strong adsorption after fiber opening, the initial dyeing temperature of nylon should be low and the heating rate should be slow to prevent discoloration. The production of flowers and stains.
Process formula (color matching): Disperse dye A dosage X (omf), disperse dye B dosage Y (omf), high temperature leveling agent 1.0g/L, acetic acid 1.0g /L (pH=4.5~5.0), liquor ratio 1:8~1:12, temperature 130℃, time 30~40min (depending on the amount of dye).
Reduction cleaning (or soaping) process: insurance powder 2.0~4.0g/L, caustic soda 2.0g/L, liquor ratio 1:10, temperature 90℃, time 20min .
New one-bath dyeing process with alkali-resistant disperse dyes
High Characteristics of alkali-resistant disperse dyes Conventional disperse dyes are dyed under acidic conditions, while fiber opening is carried out under alkaline conditions.Therefore, when conventional disperse dyes are dyed under alkaline conditions, since most of them are not resistant to alkali (especially under high temperature conditions), they will change color or even become colorless.
After a large number of experiments, it has been confirmed that conventional disperse dyes cannot achieve the one-bath process of fiber opening and dyeing; however, the use of highly alkali-resistant disperse dyes can enable fiber opening and dyeing to be carried out at the same time. Greatly shorten the process flow.
Highly alkali-resistant disperse dyes have a wide range of applications and are suitable for many varieties. They can be used under the conditions of pH=4.5~14.0; they have good lifting power and good dyeing depth; dispersion good. Due to the dyeing and drainage under alkaline conditions, it also solves the problem of oligomers that has long plagued polyester dyeing, and avoids color flowers, stains and equipment and pipeline cleaning problems caused by oligomers. There is no need to restore and clean after light and medium color dyeing, soaping can meet the requirements.
New dyeing process of highly alkali-resistant disperse dyes
1. Process flow
Bare fabric (warp knitting or weft knitting) → (pre-shaped) → fiber opening and dyeing in one bath → washing → (reduction cleaning or soaping) → dehydration → start Width shaping (padding with moisture-absorbing and quick-drying softener) → finishing.
2. Process formula
High alkali-resistant disperse dye dosage X , 30% NaOH 7.0 g/L, alkaline dispersant FA l.0 g/L, degreasing scouring agent EPD-C 1.0 g/L, liquor ratio 1:10～1:15, temperature 130℃, time 40～ 50 minutes.
3. Precautions
(1)Alkali resistance aid Agent selection. Dyeing under high temperature and high pressure alkaline conditions has higher requirements for additives: good alkali resistance (good dispersion stability at pH=14), level dyeing, hard water resistance, less foam, easy to clean, non-stick This equipment is environmentally friendly and non-toxic, and meets the environmental protection requirements of textiles. After screening more than a dozen alkaline leveling agents at home and abroad, we conducted a large number of experiments and tests, and finally selected the alkaline high-temperature dispersant FA.
(2) Due to the large specific surface area and fine fiber diameter of polyester/nylon microfiber, it absorbs disperse dyes quickly and easily causes color flowers and spots. Therefore, it must be strictly Control the heating rate, especially when the temperature is above 80℃, it should be controlled at 1.0℃/min to prevent dyeing from being dyed too fast and causing color flowers.
(3) Since highly alkali-resistant disperse dyes are more viscous than conventional disperse dyes, they must be mixed with After the dispersant is dissolved, add it to the chemical vat, stir evenly with the disperse dye, and then pour it into the dye vat. If necessary, filter it with a filter and then put it into the dye vat. After adding the dye, run it for 10 minutes first, and then slowly heat up the dye according to the program.
Dyeing effect
1. Dyeing fastness
Select the three primary colors of alkali-resistant disperse dyes, Disperse Yellow HA-2RW 100%, Disperse Red HA-R 200%, and Disperse Blue HA-RL 200%, as representatives to test their dyeing under alkaline conditions. Fastness, the results are shown in Table 1. As can be seen from Table 1, the fastnesses of the three primary colors of highly alkali-resistant disperse dyes when dyed under alkaline conditions are all above level 4, which reaches or exceeds the fastness of conventional two-bath dyeing and can meet the fastness requirements of printing and dyeing factories. .
2. Color and light changes
Respectively Test the color change when the dosage of 96010 caustic soda is 2.0 g/L, 4.0 g/L, 6.0 g/L, 8.0 g/L, and 10.0 g/L. The results are shown in Table 2. It can be seen from Table 2 that the three primary colors of highly alkali-resistant disperse dyes have stable color and light within the range of caustic soda dosage of 1-10 g/L, which can meet the needs of alkaline one-bath processing in printing and dyeing factories, and is especially suitable for polyester microfiber opening. , alkali reduction process.
Comparison between the new one-bath process and the traditional process
A large number of production practices have proven that the one-bath method of fiber opening and dyeing for polyester microfiber dyeing with highly alkali-resistant disperse dyes is completely feasible, and the product quality is stable, reproducible, and production efficiency is significantly improved. The cost is greatly reduced and it is a new process worthy of praise. Now take 1000 kg/cylinder as an example for comparison to illustrate the advantages of this process, see Table 3.
As can be seen from Table 3, the dyeing cost of the new process is 688 yuan/ton of cloth compared with the traditional process (excluding reduced sewage treatment costs), accounting for approximately 40.4 %; water saving is about 42.9%, electricity saving is about 50%, steam saving is 40%; dyeing time is saved by 50%, and production efficiency is doubled. In addition, the economic benefits of reducing sewage discharge and sewage treatment costs are very obvious.
Production cost reduction
One-bath dyeing with highly alkali-resistant disperse dyes French craftsmanship. The emergence of dyeing has completely changed the traditional two-bath dyeing method. Large-scale production has proven that it is completely feasible to use highly alkali-resistant disperse dyes and alkali-resistant and high-temperature-resistant dispersants for polyester dyeing. The total production cost will be reduced by 30% to 40%, and the production efficiency will be improved. In line with the current general trend of environmental protection, energy conservation and emission reduction advocated by the country, it is welcomed by printing and dyeing enterprises. The economic and social benefits are also very obvious, and it has broad development space.
References: [1] Guo Fulin, Guo Ming. One-bath process of alkali reduction, fiber opening/polyester dyeing of island-type microfiber fabrics [C]//Seventh Proceedings of the Guangdong Textile Auxiliary Industry Annual Conference. 2015.
[2] Wang Chao. Functional finishing and dyeing production practice of polyester and nylon microfiber terry cloth[C]//Yuhui 11th National New Materials, New Technologies and New Technologies in the Printing and Dyeing Industry Proceedings of the Technical Exchange Conference on Technology and New Products. 2012.
[3] Kang Hongwei, Guo Fulin. Application of one-bath process for reducing the amount of dyeing of pure polyester with undrained alkali [J ]. Dyeing and Finishing Technology, 2014(11):29-30.
�2015.
[2] Wang Chao. Functional finishing and dyeing production practice of polyester and nylon microfiber terry cloth[C]//Yuhui 11th National New Materials and New Technologies in the Printing and Dyeing Industry, Proceedings of the Technical Exchange Conference on New Processes and New Products. 2012.
[3] Kang Hongwei, Guo Fulin. Application of one-bath process for reduced weight dyeing of pure polyester without lint.[ J]. Dyeing and Finishing Technology, 2014(11):29-30. </p
