What are the environmentally friendly denim processing technologies?

In recent years, the pollution problem of denim processing has attracted widespread public attention, and the denim industry is facing severe challenges. The dyeing and finishing of denim garments consumes a lot of water and wastewater, and the concentration of pollutants in the wastewater is very high. Under today’s environmental protection trends, production methods that sacrifice the environment will be gradually eliminated. Major denim manufacturers have begun to introduce new technologies, new equipment, and new additives in order to achieve green transformation and development.

Environmental protection technology for denim finishing process

(1) Mercerized alkali recovery technology

In order to increase the lasting luster of cotton fibers and improve the dimensional stability of the fabric, the cotton fibers need to be mercerized with caustic soda. The residual alkali on the cotton fiber after mercerization is washed away. The concentration of these waste alkali is about 40 ~ 50g/L. If not recycled, it will not only cause waste, but also greatly increase the difficulty of sewage treatment. Due to its economic and environmental benefits, mercerized alkali recovery equipment is gradually welcomed by printing and dyeing enterprises.

(2) Resource utilization of printing and dyeing wastewater

Printing and dyeing wastewater has the characteristics of large color, large changes in COD, high alkalinity, poor biodegradability, and large changes in water temperature. It has become one of the main sources of water pollution in my country. At present, the resource utilization of printing and dyeing wastewater is less than 10%, which is far lower than other industries. Treat denim processing wastewater so that major indicators such as CODcr, suspended solids concentration, pH value, and color can meet the standards for production water or reclaimed water reuse in each process, and can be used for dyeing, rinsing, greening, cleaning, etc., thereby increasing resources Utilization rate and reduction of sewage discharge will help to improve the greenness of denim production methods.

(3) Foam technology

Foam technology uses a small amount of liquid, mixes air into the liquid through certain equipment and foaming agents, and forms metastable foam required by foam dyeing and finishing technology, and applies the foam to the fabric in a uniform state to achieve the desired effect. A new type of dyeing and finishing technology. Foam dyeing and finishing technology is a typical low-liquid-feeding and energy-saving process. It can evenly distribute chemicals under small moisture supply conditions, which is fully in line with the development direction of green dyeing and finishing.

Environmentally friendly garment washing technology

(1) Low liquor ratio water washing technology

The washing process is an important production link in the denim industry, but it has problems such as high energy consumption, high water consumption, and high pollution. Italian Tongnailu Company has developed water washing equipment with the advantages of high efficiency, energy saving, water saving, etc. The equipment has a small liquor ratio (1:5 ~ 1:7) and good processing capacity. It is equipped with the patented design JET SYSTEM system and can reach 1:2 ~ Liquor ratio of 1:3.

(2) Ozone washing technology

Ozone technology has many application advantages in denim garment processing, including reducing water and chemical consumption, shortening process time and processes, and being clean and environmentally friendly. The ozone washing machine can apply the ozone generated by the ozone generator to the garment washing process, and the ozone can produce an achromatic bleaching effect. This type of equipment is mainly used for distressing treatment of denim products. By adjusting the amount of ozone generated, different degrees of treatment effects can be achieved. Ozone washing machines do not require the use of chemicals and can save a lot of water resources, so they meet the requirements of ecological and environmental protection.

(3) Full enzymatic washing process

The full enzymatic washing process creates a new denim style by using enzyme preparations to replace chemicals in the denim processing process, ensuring that denim garment processing has a small impact on the environment.

(4) Laser engraving

The denim laser engraving process directly replaces the hand rubbing, spraying and other processes in denim washing. It can produce image patterns, gradient patterns, cat whiskers, frosting and other effects on denim fabrics, which not only increases the added value of the product, but also greatly reduces the cost. It eliminates the waste of water resources and the discharge of washing wastewater, not only ensures the cleanness and safety of the processing environment, but also caters to the trend of energy conservation and emission reduction. The laser engraving equipment adopts the principle of automated operation control system and laser non-contact thermal processing, and uses software to create personalized washing effects on denim such as stone grinding, sandblasting, 3D whiskers, tatters, etc., replacing the traditional manual hand-wiping process. Compared with the traditional tedious manual processing procedures, laser engraving only needs to import the processing graphics once, and multiple processing procedures can be completed at one time, which is more efficient and saves a lot of labor costs.

With increasingly stringent environmental protection requirements and pressure from non-governmental organizations, the labor-intensive denim industry has encountered very big challenges. In order to achieve sustainable development of enterprises, major denim processing enterprises have gradually embarked on the road of transformation and upgrading, and environmentally friendly processing technology has become an inevitable choice for enterprises.