Textile fabric testing does not pass common problem analysis

Analysis of common problems that textile fabrics fail to test and how to solve and improve them. There are two common aspects of testing items. One is a physical item and the other is a chemical item. The chemical item is also what we call environmentally harmful substances. Let's first understand a piece of data. These data have also been compared between its and bv in the three major testing institutions, which are basically consistent with the situation we encountered.
 
    The proportion of test items:
 
    1. Six-fiber fastness (including washing, sweat, and water-stained six fibers) accounted for 32% of the failed
 
    2. Anti-pilling accounted for 16%
 
    3. Wet grinding fastness 11%
 
    4. Light fastness 9%
 
    5. ph value 7%
 
    6. The torsion shrinkage rate is 5%
 
    7. Environmentally hazardous substances (Azo formaldehyde apeopcp heavy metals) 1.5%
 
    8. Other
 
    This is basically consistent with our current actual production. Among them, the color fastness basically accounts for half, and the fluffing and pilling, the light fastness, and the shrinkage of the ph knitted fabric, which account for a relatively large proportion. There is also an environmentally friendly substance. We look at the proportion of it is not high, but once the fabric Environmental protection issues will have a greater impact on the entire bulk cargo. Since these projects are not easy to pass the test, we have to explore the problem and how to solve it and improve it?
 
    The first reason why the test failed: customer standard requirements are getting higher and higher. For example, washing fastness is basically qualified for level 3 a few years ago, and now many test reports are required to be level 3-4 and level 4 even we encountered some customers. For the level 5 requirement, we can only shake our heads for this kind of order. There are also environmental protection issues. At the earliest time, no one paid attention to the apeo content, and the test was not required. Some requirements were within 300ppm. Now customers require less than 100ppm, 50ppm or even 10ppm.

Start with the six-fiber fastness to washing with the most encountered.
 
    Color fastness to washing six-color fiber
 
    1. Washing fastness is to test the fabric and six fiber strips at a certain temperature and a certain amount of soaping liquid in the same bath. The color change after washing before washing is called washing discoloration. The washed dye sticks to the six fibers. The degree of grading by gray card is called staining fastness. Wool nitrile polyester nylon cotton diacetate fiber. Generally, polyester, cotton, and nylon are basically not problematic. Our dyeing factory can achieve level 3-4 or higher. Many of us can achieve level 4 when we see dark colors, but we found that all polyester spandex fabrics and their blended fabrics are placed in When dyeing medium and dark colors together, washing with water is generally not good. Why? This is because polyester disperse dye stains the spandex very seriously, and when we use sodium hydroxide and soda ash for reduction cleaning, the surface of the polyester is floating. Basically, it can be cleaned, but the stain on the spandex is not clean, so more often our polyester + spandex products, the medium-dark washed six-fiber stain is basically around 2-3.
 
    Moreover, our Shaoxing dyeing plant likes high temperature for final product setting. Disperse dyes will sublime when the temperature exceeds 140 degrees. This is why we have to set low temperature in the last process when we do high fastness.
 
    The washing fastness of polyester+nylon fabrics is not good. Why, when dyeing nylon polyester with fast dyes or most of Shaoxing dyed with disperse dyes, staining of nylon will be serious. These stains cannot be fixed by fixing Increasing the fastness and cleaning will cause a lot of color change, so the dark color fastness of nylon polyester fabrics is still a pain point in the industry.
 
    There is also a common suede fabric in Shaoxing. The scientific name is added with sea-island silk, which is also a kind of polyester. The fiber opening process in Shaoxing area is generally not ideal. The fiber cannot fully open the pores and the crystal change is low. Therefore, the dyeing is in the same color depth. Under the circumstances, the owf concentration is much higher than that of conventional polyester, and the dye concentration is also much higher. His medium and dark colors are dyed. We describe it as more like the color piled up by dyes. This floating color is very serious and the color is fast after washing. The degree is a lot at level 1.5 and level 2 and level 2.5. Dyeing factories in Fujian and Guangdong have done a good job of fiber opening technology, and some can achieve level 3 3-4.
 
    Other fabrics such as polyester/cotton/nylon/cotton can basically meet the requirements through double-fixed washing fastness through correct soaping and fixing of nylon/cotton. Our high fastness is basically polyester + spandex products, we need to choose high fastness dyes.
 
    2. Rubbing fastness. The rubbing fastness is not unfamiliar to everyone, as: dry grinding and wet grinding. Polyester nylon fabrics have very few friction problems. Most of the cellulose fibers such as cotton, rayon, linen and their blended products will have friction problems in the medium and dark colors. This is determined by the characteristics of the reactive dyes they use for dyeing. Reactive dyes form a covalent bond with the fiber during dyeing. If the dry grinding is not good, we can judge that the cloth surface has no floating color. It can be solved by fixing and soaping. Wet grinding is because the reactive dyes are under a certain pressure and humidity. The bottom is easy to fall off, so the wet-milled bulk of fiber cotton, rayon, cotton and linen fabric is basically around 2.5. This is solved by the nature of reactive dyes.
 
    Improvement plan: First: sufficient pre-treatment, more uniform color eating, and better fastness; second: strengthen soaping and clean floating color. If you want to reach the third level of wet grinding, you can increase it by humidifying the wet grinding enhancer when setting the shape. This product is now relatively mature, and it is basically improved by half to about one level.
 
    3. The ph value is commonly known as the acidity and alkalinity with numbers 1-14. The median value of 7 is neutral, and less than 7 is acidic. The smaller the number, the greater the acidity, and the greater the number is alkaline. The larger the number, the stronger the alkalinity. The 18401 standard a category 4-7.5 is judged to be qualified, but now many of our customers’ corporate standards set the ph between 5.5-7.5 and some between 6-7. This large product will be more difficult to realize. Now let's analyze why the pH of our fabrics can't meet the requirements: This needs to be understood from the last process when we dye:
 
    For example, polyester dyeing is dyed under acidic conditions, but during reduction cleaning, it is necessary to add sodium hydroxide and soda ash to clean the floating color, and then adjust the pH before leaving the tank with ice vinegar. The glacial acetic acid is relatively strong and the pH adjustment is unstable, so it is often dyed. The ph is about 8-9 for alkaline, or the ice vinegar is too acidic and does not meet the standard.
 
    Cotton, rayon, linen and blended fabrics need to be dyed with soda ash during reactive dyeing. The dye and fiber form a covalent bond. The soaping agent used for soaping is also weakly alkaline. Finally, adjust the pH with ice vinegar before using it, just like polyester. In the case of ice vinegar, the unstable pH of ice vinegar can easily cause pH to be too alkaline or excessive acidity of ice vinegar does not meet the standard. In addition, the dyeing factory simply does not adjust the pH and releases the tank. Using citric acid to adjust the setting machine will cause the pH to be unstable or the hand feel is not soft.
 
    Nylon and blended fabrics Shaoxing Dyeing Factory will put nylon dyeing at the end. Dyeing is done under acidic conditions and the fixation is also carried out under acidic conditions. Therefore, the ph4-6.5 of nylon fabrics has relatively few problems, and excessive acid fixing agent will also occur. Partial acid 4 or less.
 
    Conclusion: The ph can be adjusted to within 4-7.5 or 5.5-7.5 with ice vinegar through professional calculations before the tank is released. However, many dyeing factories in Shaoxing now rely on the experience of color masters to adjust, so some errors will occur. . For some sensitive light colors such as bleaching white or bright yellow and green, which are prone to yellowing or discoloration after the cylinder is set, we will also use a color protectant. One can keep the color placed and set the color to become smaller, and the second can also be achieved. Adjust ph between 5-7.5.

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