Research on Clean Production Technology in Textile Printing and Dyeing Industry

With the rapid development of social production and the acceleration of industrialization, the problem of environmental pollution has become increasingly prominent. Wastewater from industrial production and urban construction has become a serious source of pollution. Water pollution has led to a shortage of water sources and deteriorating water quality, which has become an important factor limiting the sustainable development of the economy and society. Therefore, the control and prevention of wastewater pollution has received widespread attention, and the promotion of cleaner production has become an inevitable trend of social and economic development.

For many years, the treatment of waste and wastewater in the printing and dyeing industry has been dominated by end-of-pipe treatment. However, single end-of-pipe treatment has become a heavy burden for economic development, and it cannot effectively solve environmental pollution problems. It is necessary to reconsider environmental governance policies. In this regard, the developed countries took the lead in proposing a new method to promote the coordinated development of the economy and the environment - cleaner production.

With the in-depth development of cleaner production, countries around the world have continued to open up new fields in practice, and have gradually expanded from the initial chemical companies to the first, second and third industries. Although there is no mature indicator system and technical specifications for clean production in the printing and dyeing industry, we can learn from the successful experience of other companies in cleaner production. Introduce clean production theory. Promoting clean production in the printing and dyeing industry can fundamentally prevent and reduce environmental pollution and ensure continuous improvement of environmental quality .

First, the concept and content of cleaner production in the printing and dyeing industry

The clean production of the printing and dyeing industry is to continuously apply the pollution prevention strategy to the whole process of printing and dyeing production. Through scientific and rational management, the printing and dyeing technology is continuously improved, the utilization rate of raw materials is improved, and pollutant emissions are reduced. To reduce the harm to the environment and humans. Promoting clean production is an important means to solve the environmental problems in China's printing and dyeing industry, to produce safe and qualified products, and to achieve sustainable development of printing and dyeing enterprises . The clean production of printing and dyeing industry runs through the whole process of production and waste disposal. The whole process control of production includes clean energy and raw materials input, clean working environment, clean printing and dyeing products; the whole process of waste disposal includes waste reduction, harmless and resource utilization in the printing and dyeing industry.

Second, the pre-treatment process of dyeing and finishing clean production technology

The amount of wastewater generated by the pretreatment process is very considerable, accounting for 50% to 60% of the amount of printing and dyeing wastewater, and water conservation is of great significance. The use of high-efficiency short process technology, the use of high-efficiency additives, shorten processing time, can reduce the amount of additives and water. Compared with the traditional three-step process of retreating, boiling and bleaching, the high-efficiency bleaching aid and the alkali-oxygen one-step cold-rolling process can save about 2 times of water, save 1.8 times of electricity, and save 3 times of steam, saving resources. And the energy effect is obvious; the low temperature and low alkali pretreatment process can not only save energy, but also reduce the alkali content of wastewater, which is beneficial to the treatment of wastewater; and develop a new generation of green surfactants and ecological additives in the pretreatment process. Technology, such as biological enzyme desizing, refining and other biological enzyme pretreatment technology, can not only avoid the use of alkaline agents, greatly reduce the use of chemicals, reduce wastewater discharge, and improve the biodegradability of pollutants in wastewater. The composite biological enzyme can be used in the alkali-free room temperature decoction process, and the high temperature and strong alkali removal fabric slurry and its commensal have gradually begun to be replaced by the desizing refining of the composite biological enzyme. For some textiles with less impurities, a small bath ratio or foam bath can be used to process under less water conditions. In recent years, the use of plasma technology or other ion sputtering technology, laser technology, ultrasonic technology and ultraviolet radiation technology to remove impurities on the surface of the fabric has made great progress.

Third, the dyeing process of dyeing and finishing production technology

The dyeing process is the main process of pollution in the printing and dyeing industry, and it is of great significance to promote clean production in this process. For example, if the fiber is modified, the dyeing performance is improved, and the dye with high fixing rate and high utilization rate is applied, the dyeing process and equipment for developing high dye utilization rate are good clean production methods. BURKINSHAW and other studies believe that dendritic macromolecular pretreated cotton fabric can significantly improve the dye uptake rate of reactive dyes , and even achieve salt-free dyeing. Researchers have also done a lot of research work on fabric modification to achieve salt-free dyeing of reactive dyes.

The use of UV, microwave and high-energy radiation to treat textiles can also improve the dyeing properties of the fibers, and some can also be used directly for fixing. The bath ratio of small bath ratio dyeing equipment can reach (1:4)～(1:6), which not only saves dyes and additives, but also reduces waste water discharge and dye residue, which can save dyeing materials by 30% and save The water consumption is 40%. Some scholars have studied the use of ultrasonic dyeing to improve the dye uptake rate and save energy in a short period of time.

One of the purposes of cleaner production is to minimize the consumption of water, dyes and energy, and waterless dyeing technology makes it possible. Non-aqueous or water-free dyeing is an important method for clean dyeing. In recent years, supercritical carbon dioxide has been used as a dyeing medium, and dyeing is not used. After dyeing, it is generally washed without water or lightly washed, and carbon dioxide can be reused. The method has the advantages of no water, no pollution, short dyeing time, low energy consumption, and residual dye recycling, and is a direction for future dyeing development.

Fourth, the printing process of dyeing and finishing production technology

The pollution of printed paste is more serious. At present, some new types of pastes are mainly obtained by modifying natural polymer compounds and synthesizing them using petrochemical raw materials. These new types of pastes are low in dosage and easy to recycle and purify. The paint printing process is short, does not need to be washed, and conforms to the ecological principle. It should actively develop new coatings, harmless adhesives and high-efficiency thickeners to solve the problems of hand feeling, fastness and vividness. In recent years, printing technology has developed rapidly, and green printing processes such as digital inkjet printing, transfer printing, and electrophotographic printing have been continuously developed. Digital inkjet printing can save a certain amount of water, and is a production process that meets the requirements of clean production. The transfer printing is done in the production process without water or water. The water consumption of natural fiber fabric transfer printing is only 1/10 of that of traditional printing. It does not need to be steamed or re-baked after printing, which can save a lot of water resources and reduce environmental pollution. However, a large amount of transfer paper is required, and these transfer papers are difficult to reuse after use.

Fifth, dyeing and finishing of cleaner production technologies finishing process

The following measures can be used in the finishing process to implement clean production: full use of calendering, embossing, electro-optic, embossing, sanding, softening, pre-shrinking, napping and other mechanical finishing. For example: the newly developed soft finishing technology, which is a method of processing a variety of physical and mechanical effects, such as air flow conduction expansion, mechanical slap, and the like. The finished fabric is soft, full, smooth and fluffy, and the structure is active. The use of chemicals is reduced during processing, resulting in less damage to the fabric fibers and less damage to the human body and the environment. By physical and chemical methods, such as low-temperature plasma treatment, softening can be obtained, moisture absorption and antistatic properties of synthetic fibers can be improved, the gloss of fibers can be improved, and the cohesion between fibers can be increased. The use of biological enzymes for the polishing and soft finishing of cellulose fibers and protein fiber textiles, as well as the improvement of itching of textiles such as ramie.

Foam dyeing is a low-liquid dyeing and finishing process in which the dyeing and finishing working solution is foamed to form a foam system and then applied to the fabric. Foam processing can increase production efficiency, reduce wastewater, and reduce chemical consumption. In the process of water repellent, oil repellent, hydrophilic, soft, flame retardant, etc., the use of foam technology can achieve good results, and can reduce energy consumption and reduce environmental pollution.

As the clean production work in China's printing and dyeing industry started late, there is not much accumulated experience, and various problems will inevitably arise in the process of promotion. However, it should be believed that with the continuous promotion of clean production and the continuous enrichment of experience, these problems will be solved.