Color fastness is the degree of fading and staining of clothing colors. The mandatory national standard GB18401-2003 "National Basic Safety Technical Specification for Textile Products" stipulates that the various color fastness indicators of qualified products must be greater than or equal to 3 levels.  The color fastness ratings are: Level 1, Level 1-2, Level 2, Level 2-3, Level 3, Level 3-4, Level 4, Level 4-5, Level 5 . 5th, 9th , 1st, worst, 5th ( no fade ) . Level 3 can only be a basic level and it is an intermediate level.  Textile color fastness usually includes:  Soap resistant, rub-resistant, light-resistant, bleach-resistant or resistant to oxidants <reducing agent>, resistance to ironing, sweating resistance, and sweat-fastness.  Among them, soaping resistance, friction resistance, light resistance, water resistance, and perspiration resistance are some of the indicators of color fastness that most buyers in actual production and trade are paying close attention to.  Soap wash fastness  1 , soaping color fastness test method comparison  Soaping color fastness is one of the most common color fastness assessment items. The color fastness of soaping refers to the degree of fading of the dyed fabric after soaping under the specified conditions. It includes the two evaluation items of fading and white cloth staining. Fading refers to the fact that the colored fabric is discolored before and after soaping ; the white fabric staining is the situation in which the white fabric and the colored fabric are sewn together in a certain manner, and after the soaping, the white fabric is stained due to the discoloration of the colored fabric. The degree of fading or staining shall be tested under the specified light source, and shall be rated on a standard grey card. The results shall be divided into 5 grades, with 5 being the best and 1 being the worst.  2 , dye structure, dyeing and post-treatment process and soap color fastness relationship  In routine testing, a considerable part of textiles, including cotton, wool, polyester, nylon and blended fabrics, and elastic fabrics containing spandex, nylon, and acetate fibers are attached to the liner in the staining of grade 3 or 3 or less. Although the dyes and printing and dyeing processes used by different fiber materials are different, the problems are quite similar. This is mainly related to the transfer of the floating color of the fabric and the part of the colored nits, and thus is also associated with the type of dye used, the dyeing process and the post-treatment process.  3. The color fastness of soap dyeing of reactive dyeing products depends on the unfixed dye  Taking reactive dyes as an example, theoretically speaking, because dyes and fibers form covalent bonds, water washing does not easily cause dye desorption, discoloration, and bleed. Therefore, the color fastness of soap dyeing products for reactive dyes is determined by The amount of unfixed dye ( hydrolyzed dye and a small amount of unreacted dye ) . If the hydrolyzed dye soaping is not removed, subsequent washing will appear continuous fade. Soaping fastness is also related to the bonding stability of bonded dyes, and broken dyes can also be washed away. Therefore, the factors affecting the color fastness of soaping are the dye structure and properties, followed by dyeing and post-treatment. Reactive dye fixing rate, or slow the rate of hydrolysis, hydrolysis of dye is small, the amount of dye removed to be cleaned less. Unfixed dyes and hydrolyzed dyes have low direct, good water solubility, are not easy to stain, and are easy to wash. The high concentration of dyes and residual dyes are not easy to clean.  4 , soaping fastness is closely related to the dyeing process  In addition, the soaping fastness is also closely related to the dyeing process. Adsorption and diffusion of the dye are sufficient, the fixation rate is high, residual dyes and hydrolyzed dyes are few, and it is easy to wash away. The dyeing process is reasonable, and the covalent bond between the dye and the fiber is not easily broken during dyeing and post-treatment, and the soaping has good color fastness.  Color fastness to rubbing  1. Comparison of test methods for rubbing fastness  The rubbing fastness test refers to the test that the colored sample is rubbed with a dry rubbing cloth and a wet rubbing cloth, respectively, and then the degree of rubbing of the rubbing cloth is evaluated. Test results are divided into 5 levels, 5 best and 1 worst. Although the testing process is simple, but it is the basic color fastness assessment index of textile products, almost one of the items that must be assessed when buyers place orders. The technical conditions for testing standards for crockfastness in various countries are very similar, but there are also some differences.  2. Main factors that affect the color fastness to rubbing and its control measures  In the process of rubbing textiles with other objects, the degree of color shedding or the degree of staining of rubbed objects is affected by many factors.  There are two ways to get rid of color :  First, the dyes on textiles fall off or fade, contaminating the surface of the friction object ;  The second is that the dyed fiber falls off and sticks to the surface of the friction object.  3 , in practice, dye shedding is the main reason for staining  Although there are some differences in the covalent bond strength and adhesion between the reactive dyes of different chemical structures and cellulose fibers, the effect on the color fastness to wet rubbing of dyed fabrics is basically the same. When the dyed fabric is wet rubbed, the covalent bond formed between the dye and the fiber does not break and float color occurs. The dyes that have undergone transfer usually do not form covalent bonds with the fibers, but rely solely on van der Waals forces for adsorption, that is, floating color.  Light fastness  1. Comparison of test methods for light fastness  The lightfastness test is to test the colour fastness by comparing the textile sample with a set of blue wool standard under the artificial light source and subjecting it to the specified conditions, and then comparing them by discoloration.  2 , to improve the fastness to light fastness  The mechanism of photofading of dyes is very complicated, but the dye is mainly absorbed by the photons, and a series of photochemical reactions occur to destroy the structure, resulting in discoloration and discoloration. The light fastness of textiles depends mainly on the chemical structure of the dye, as well as its state of aggregation, state of bonding, and the state of mixed colors. Therefore, the rational choice of dye is very important.  3 , according to fiber properties and textile use  For cellulose fiber textiles, dyes with good anti-oxidation properties should be used ; for protein fibers , dyes with good resistance to reduction or containing weak oxidative additives should be used ; other fibers should be selected based on the effect on fading. In order to enhance the photo-oxidative 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 in the dye synthesis process , thereby reducing the electron cloud density of the azo gas atom. In addition , it is also possible to introduce hydroxyl groups at two ortho positions of the azo group and utilize its coordination ability to complex with heavy metals, thereby reducing the electron cloud density of the azo hydrogen atoms and shielding the azo groups, ultimately increasing Dye light fastness.  4 , should choose according to the depth of color dye  A large number of tests have proved that the light fastness of reactive dyes on cellulose fibers is directly proportional to the depth of the dyed shades, ie, the darker the color, the better the light fastness to color. This is due to the higher concentration of 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 exposed to air, moisture and light, and the lower the probability of the dye being photo-oxidized. On the contrary, the lighter the color , the dye is mostly highly dispersed on the fiber, and the chance of receiving light is higher, and the light fastness is eventually reduced. Therefore, for dyeing light-colored varieties, dyes with higher light fastness should be used. In addition, many post-finishing agents such as softeners and crease-reducing finishes are added to the fabric, which also reduces the light fastness of the product. Therefore , dyes that are insensitive to these finishes should be selected.  5 , should use light stability, compatibility of good dye color  The discoloration properties of different dyes are different, and even the mechanism of light fade is different. Occasionally, the presence of a dye sensitizes the discoloration of another dye. When mixed colors should be used with each other without sensitization, or even can be improved light stability of the dye, which dye in a dark color such as black when particularly important. Discoloration of one dye in the three primary colors too quickly will quickly cause discoloration of the dyed fiber or fabric, and the faded dye residue will also affect the light stability of the other two dyes that have not faded. Reasonably control the dyeing process , make the dye and fiber fully combined, try to avoid the hydrolysis dye and unfixed dye residue on the fiber, is an important way to obtain high light fastness.  Water / sweat fastness  1 ã€Comparison of test methods for water fastness, perspiration resistance and perspiration  The color fastness to water reflects the self-discoloration of the textile under the combined effect of certain moisture, pressure and temperature, and the staining of the lining fabric. During the test, after the sample and the liner fabric are fully wetted, they are placed in a certain temperature oven for a certain period of time under a certain pressure, removed and dried, and evaluated for color change and stain progression. The discoloration and staining levels are divided into 5 levels, with 5 being the best and 1 being the worst.  Perspiration fastness is a reflection of textiles in different test solutions containing histidine, under the combined effect of pressure and temperature, self-discoloration and staining of the lining fabric. Gray cards were used to evaluate the discoloration of the samples and the staining of the lining fabrics . The results were divided into 5 grades, 5 grades being the best, and grade 1 being the worst.  2. Ways to improve the color fastness to water and perspiration  To improve the water fastness and sweat fastness of fabrics, the most important approach is to use dyes rationally. In particular, dyes with high fixing rate and good stability should be used. Reasonably formulate and control the dyeing process, strengthen the fixing conditions, and form a high stability of the covalent bond, which can fully fix the dye. For example, a catalyst may be used for dyeing a less reactive dye, or an appropriate fixing agent may be used, or fixed at a relatively high temperature.  Zhejiang Bolong International Industry&Trade CO.,LTD , https://www.bolongjackets.com
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