Measures to Improve the Color Fastness of Jinan Elastic Knitted Fabrics

With the increasing demand for the performance of nylon and nylon-based stretch knitted fabrics, the color fastness of the dyed products, especially the medium and deep colors, has become the focus of the majority of printing and dyeing technicians. Especially for some high-end products that have to undergo high-temperature stamping and other treatments, the requirements for washing, staining, perspiration, water stains, etc. are often required to reach level 4 or higher, so how to further improve the color of nylon products. The fastness is especially important. The following is for discussion and reference for peers.

The main reason for the color fastness of the ammonia products is the structural characteristics of the nylon fibers. The crystallinity and orientation of the nylon fibers are relatively high. The molecular chain does not contain branches, and only a small amount of -NH2 is present at both ends of the main chain. This makes the dye dyed part of the ionic bond mostly based on the intermolecular attraction between the dye and the fiber and the hydrogen bond, but the combination is not very strong, and it is often difficult to order in higher orders. To meet the requirements, it must be achieved through improvements such as fixing and the following processes or operations.

The specific measures are:

1. Choose a suitable dye: nylon can be dyed with a variety of dyes, such as dispersion, neutral, weak acidity, activity and even cations, but each has its own advantages and disadvantages, combining its color fastness, color yield and cross-cutting The hiding ability of the file is based on the use of disperse dyes in light colors, and weak acid and neutral dyes in medium and dark colors. Especially the neutral dye has a large molecular structure, strong interaction with the fiber, high dye uptake rate and low water solubility of the dye itself, so the wet treatment fastness is relatively good, but its initial dyeing rate is high. Uniform dyeing differential chromatography is also incomplete, complementary to weak acidity. Of course, it is better to use nylon-based dyes with high wet fastness, but it is not popular because of its high price and harsh dyeing process.

2. Strengthening pre-treatment and degreasing: Jinmi, especially ultra-fine fiber, contains more chemical fiber oil, even up to 8%, and spandex also contains more silicone oil. If these oils are not adequately removed or Residue on the cloth will not only cause color stains, but also lead to a decrease in fastness. Therefore, it is necessary to select an auxiliary agent with strong emulsification and degreasing ability, which can be carried out together with the relaxation treatment to prevent condensation or generation of the removed oil agent. Secondary anti-stick phenomenon.

3. Strengthening post-dyeing cleaning: Washing and cleaning method after nylon dyeing is also an important part of dyeing fastness. Practice shows that anti-stick soaping agent 1-2g/l, soda ash 0.5g/l, 55-60°C treatment 20′ ratio Single water washing can effectively improve the fastness. For the more demanding, it can be treated with the first anti-soak soaping treatment. After the water is washed, the weak acid soaping can further improve the color fastness.

4. Pay attention to fixing treatment: After weak acid dyeing, it must be fixed by color treatment. It can improve the washability of nylon by 70-80 °C×20-30′PH4.5 after selecting suitable fixing agent with excellent performance. It is resistant to perspiration and other fastness and can meet the general requirements of fastness. However, for the double-fixing process with a strict requirement of fixing the color of the cationic fixing agent 5-10g/l with the first acid fixing agent, a higher level of fastness can be obtained.

5. For the nylon fabric, due to the dispersion of the spandex, it will often lead to a decrease in the fastness to washing and staining . If a spandex toner is used , the weak acid dye can be dyed with the two fibers in the same bath. It can effectively improve the color and fastness of the two phases. At present, such additives have been sold in the market, such as Zhejiang Chuanhua.

6. Other process requirements and points of attention: In the factors affecting the fastness of the ammonia, in addition to paying attention to the above several items, of course, dyeing bath PH control, dyeing temperature and holding time, setting temperature, including moisture absorption row The choice of sweat and softener can affect the fastness, and the degree of influence is different. The use of specific tests should be carried out to select the auxiliary or process which has the least impact and is more effective for improving the fastness.

Practice has shown that taking into account the above various treatments can completely achieve the darkness fastness of the uranium class to level 4 and above, meeting the demand of customers with higher requirements.

Source: Printing and dyeing station

Edit: Printing and dyeing e station

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