New Dyeing Process in 2022 (Green Dyeing Technology)-2

The new dyeing process includes new technologies such as waterless dyeing and low-temperature dyeing, in addition to the use of natural dyes and computer-controlled dyeing mentioned in the previous article. Now let\'s look at the specific situation of these related processes.

Waterless dyeing process

Waterless dyeing is an important dyeing process for reducing dye waste , and there are many types.

Solvent Dyeing

In the 1960s and 1970s, solvent dyeing was studied and popularized in China. WhileSolvent dyeing has many advantages, some solvents, such as halogenated hydrocarbons, are harmful to the environment. In addition, the solvent recovery equipment has yet to be expanded, so it has yet to be popularized and applied.

Supercritical carbon dioxide drying

Supercritical carbon dioxide liquid has been used as a staining medium in recent years. Its most notable feature is that it does not stain with water. It can generally be washed without water or only lightly after dyeing. And carbon dioxide is vaporized and then converted into a supercritical fluid, which can still be reused and is considered the ideal dyeing process.

The main problems with current industrial production are the high cost of production equipment and the fact that they geei only for non-ionic dyes, such as dispersed drying synthetic fibersnet is. In addition, the variety of dyes is insufficient and these deficiencies need to be addressed in the future.

Electromagnetic dyeing

Dyes are formed into charged or magnetic particles which are then electrostatically or magnetically attracted to textiles in an electric currentc or magnetic field. The dyes on the fabric are then absorbed, diffused and fixed in the fibers by thermal baking, steaming or hot pressing.

After dyeing, the process can be completed simply by general washing or by removing unfixed dyes from the fabric Fibers using electric or magnetic fields. This is preliminary research.

Sublimation dyeing process

Water is not used as a dyeing medium in steam dyeing, also known as sublimation dyeing. Under higher temperature or vacuum conditions, it sublimes the dye into the gas phase where it is adsorbed and diffused in the fiber. DThis method of vacuum metallization has been used for a long time. The difference is that a metal coating forms only a metal film on the surface of a fiber. In gas-phase or sublimation dyeing, the dye is not only absorbed on the surface of the textile, but also diffuses into the fiber and becomes fixed in it at a certain temperature. This is where the dyeing process occurs.

This typeThe dye transfer and dyeing mechanism of the dyeing process is similar to that of thermal transfer printing, which requires strong dye sublimation. At present, it is mainly some nonionic disperse dyes or dyes that can be easily sublimated, since no washing is required. With water after dyeing, there is no waste water, which is good for the environment.

New color dyeing

The dyeing process of the Color does not take place and the color is mainly attached to the fabric by adhesives. The The simple procedure ist its main advantage. Regardless of whether it is a single natural or synthetic fiber fabric or a mixture of several fibers, it only needs to be varnished once. In addition, no or only light water washing is required after dyeing, resulting in less waste water and energy savings. The main disadvantages are the lack of haptics and some adhesives are toxic (e.g. contain formaldehyde or non-toxic free monomers).

The first step in researching new paintA goal is to select safe paints and adhesives and the second step is to improve the hand and color brilliance of dyed fabrics. Some paints and adhesives that meet environmental standards are now available. Make some extra soft glues or reduce the amount of glues and appropriately control the distribution of the glues on the fabrics to improve the fabric\'s hand. For example, the ForResearch and development of adhesive-coated coatings for dyeing significantly improves the hand and breathability of textiles as well as the fastness.

Salt-free dyeing method

When dyeing ionic dyes, especially some reactive and direct dyes with low directness, it is often necessary to add a large amount of neutral electrolytes such as salt and Yuanming powder to increase the dyeing speed of dyes . After dyeing, all of these electrolytes are discharged into the dye effluent, polluting the river. Using high directness dyes can help reduce the amount of salt used. Additionally, chemically modifying fibers to improve their ability to absorb dyes can reduce the amount of salt.

Cellulose fibers have been aminated and modified in recent years. The adsorption capacity of direct, reactive, and other anionic Ffibers By adding positively charged quaternary ammonium groups to the cellulose fibers, the dyes on the fibers are significantly improved, which enables low-salt or salt-free dyeing. When dyeing with reactive dyes, it can even be fixed under neutral conditions, which reduces the amount of alkali required and is therefore good for the environment.

Use of \"green\" dyeing auxiliaries

Heavy metals on dyed textiles mainly come from dyeing and Processing ingredients and fiber and textile processing materials. Some dyes or pigments, for example, may contain heavy metal ions, as well as some dye mordants (like hexavalent chromium salts) and fixatives (like divalent copper salts).

Dyes, mordants and fixatives containing harmful substancesIn recent years, Ardous- Heavy metal ions researched and crafted without or instead. Acid mordants, for example, do not use a dichromate as Bstimulants, and direct dyes do not require copper salts as fixatives. Some have been re-examined and created mordants and color fixatives, such as B. Formaldehyde-free color fixatives do not contain formaldehyde or other dangerous compounds. Some carriers containing halogenated aromatic hydrocarbons and high-temperature leveling agents are also harmful dyeing auxiliaries that should be replaced with safer auxiliaries.

Low-temperature dyeing process

Usually, dyeing must be done at temperatures close to 100℃, and the high-temperature and high-pressure drying temperature of disperse dyes can reach 130℃. High drying temperatures not only consume more energy, but also easily damage textiles and dyes.

For this reason, low-temperature drying technologies are actively being developed at home and abroad, such as:

Wool factoryAt 80-90 °C dyed fabrics. Cold felt dyeing with reactive dyestoff. Solubilizing disperse dyes, acid dyes and other dyes with special dyeing auxiliaries can lower the dyeing temperature. After the application of physico-chemical or chemical methods of textile modification, the drying temperature can be lowered to carry out low-temperature dyeing. Physical and physico-chemical staining

Physical and physico-chemical approaches can be used to improve staining, so that the staining speed can be greatly improved or the adsorption capacity of the dye can be increased.

The use of ultrasound in the dyeing process is an example of a physical approach. The dyeing speed of dyes is drastically increased by ultrasonic waves, and the penetration and leveling effects can be greatly improved. Several studies are currently being conducted on the use of direct dyes and reactive dyesdyes. This can also reduce the amount of rib active ingredients and electrolytes, which is good for the environment.

Fiber dyeabilityBy plasma altering textiles at low temperature, properties can be improved. For example, wool and some synthetic fabrics can be treated with low-temperature plasma to increase the dyeing speed while lowering the dyeing temperature.

The application of UV radiation, microwaves and high-energy rays to textiles can improve dyeability, and some are used directly for dye fixation.

Physical and physico-chemical drying processes can limit chemical contamination of dye waste, but care should be taken when handling textiles. These dyeing techniques are still at an early stage of development.

Conclusion

The global issue of the world textile industry at the beginning of the 21st century and eIn important content related to the quality of human existence and sustainable development is the development of cleaner production in the textile industry, the use of environmentally friendly production methods that help protect the environment and the provision of ecological textiles to consumers. Therefore, research into these new dyeing processes is crucial.

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