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fabric's sunlight color fastness

fabric's sunlight color fastness

Aug 04, 2018

     The color fastness of the fabric is an important indicator for testing the quality of the fabric; and our most common color fastness test is mainly from the three aspects of washing, light resistance and friction. Today we will introduce the color fastness to light. .

         The light fastness test is to measure the color fastness by placing the textile sample together with a set of blue wool standards under an artificial light source and exposing it according to the specified conditions, and then comparing the two colors.

       The light fastness of textiles mainly depends on the chemical structure of the dye, as well as its aggregation state, bonding state and mixed color matching. Therefore, the rational use of dyes is very important.

       So how to choose a reasonable dye?

Select dyes based on fiber properties and textile use

     ◆ For cellulose fiber textiles, dyes with better oxidation resistance should be used;

     ◆ For protein fibers, dyes with good resistance to reduction or weak oxidizing additives should be used;

     ◆ Other fibers should be selected based on the effect on fading.

     In order to enhance the photooxidative stability of the azo group in the dye molecular structure, some strong electron withdrawing groups are usually introduced in the ortho position of the azo group during the dye synthesis process, thereby reducing the electron cloud density of the azo group gas atom. In addition, it is also possible to introduce a hydroxyl group in two ortho positions of the azo group, and to utilize its coordination ability to complex with a heavy metal, thereby reducing the electron cloud density of the azo hydrogen atom and shielding the azo group. Improve the light fastness of the dye.

Dyes should be selected according to color depth

      A large number of tests have shown that the deeper the color, the better the light fastness to light. This is because the higher the concentration of the dye on the fiber, the greater the degree of aggregation of the dye molecules, the smaller the surface area of the same amount of dye in contact with air, moisture and light, and the lower the probability of photooxidation of the dye. Conversely, the lighter the color, the worse the light fastness to light. In addition, many finishing agents such as softeners and anti-crease finishes are added to the fabric to reduce the light fastness of the product. Therefore, dyes that are insensitive to these finishes and have high light fastness should be used.

Color matching should be selected for dyes with good light stability and compatibility.

     Different dyes have different fading properties, and even the light fading mechanism is different. Therefore, when color matching, dyes that do not sensitize each other and even improve light stability should be selected, which is especially important when dyeing dark varieties such as black.

     A dye in the three primary colors fades too quickly and will quickly cause discoloration of the dyed fibers or fabric, while the faded dye residue will also affect the photostability of the other two dyes that are not faded. Reasonable control of the dyeing process, the dye and fiber are fully combined, and the hydrolysis dye and the unfixed dye remain on the fiber as much as possible, which is an important way to obtain high light fastness.

Fluorescent fabric refers to a fabric that has a strong reflective effect after fluorescent dyeing or coating finishing of ordinary fabrics. The use of fluorescent fabrics provides strong warning and safety prevention for targets that are far away or that are strongly reflected by targets in the dark. Therefore, the importance of color fastness to fluorescent fabrics is conceivable.

        The fluorescent polyester/cotton interwoven fabric produced by Yestex  is made of polyester, which is easy to dye bright colors. The back is high-strength cotton, strong and comfortable, and it meets the EN20471 standard. The high-quality dyeing process makes the fabrics bright and colorful, good wear resistance, tear resistance and color fastness extend the service life of the fabric; at the same time, in order to better meet the needs of the masses, we develop on the basis of fluorescent fabrics. Anti-static, waterproof, flame retardant and other functional composite fluorescent fabrics.


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