Causes of yellowing of clothing
Photoyellowing:Photoyellowing refers to the yellowing of the surface of textile clothing due to the oxidation and cleavage reaction of molecules caused by the exposure to sunlight or ultraviolet light. Photoyellowing is most common in light-colored clothing, bleached fabrics, and whitening treated fabrics. After the fabric is illuminated, the light energy is transferred to the fabric dye, causing the dye conjugate to cleave, causing light fading and the surface of the fabric to appear yellow. Among them, visible light and ultraviolet light are the main factors causing fading of fabrics dyed with azo dyes and phthalocyanine dyes respectively.
Phenol yellowing:Phenol yellowing is generally caused by the contact transfer between NOX and phenolic compounds. The surface of the fabric turns yellow, and the main reaction substance is usually antioxidants contained in packaging materials, such as butylphenol (BHT). After clothing and footwear are packaged and transported for a long time after leaving the factory, the BHT in the packaging materials will react with NOX in the air, causing the clothing to turn yellow.
Oxidative yellowing: Oxidative yellowing refers to the oxidation of fabrics by the atmosphere or other substances. Yellowing. Textile garments usually use reducing dyes or auxiliaries during dyeing and finishing. After contact with oxidizing gases, oxidation-reduction occurs and yellowing occurs.
Whitening agent yellowing: Whitening agent yellowing mainly occurs on light-colored fabrics. When the residual whitening agent on the surface of the clothing migrates due to long-term storage, it leads to excessive local whitening agent and yellowing of the clothing.
Softener yellowing:The softening additives used in the finishing process of clothing will change when exposed to heat. When exposed to sunlight, light and other conditions, the cations in it will oxidize, causing the softened parts of the fabric to turn yellow.
Although yellowing is divided into the above five types, in actual use, clothing yellowing is usually It is formed by the superposition of multiple reasons.
How to prevent clothing from yellowing
(1) Enterprises should minimize the use of whitening agents in the production and processing technology, and shall not exceed the yellowing point of the whitening agent.
(2) When finishing and shaping the fabric, the temperature should not be too high. High temperature will oxidize the dyes or additives on the fabric surface. cracking, causing the fabric to yellow.
(3) During the packaging, storage and transportation processes, use packaging materials with lower BHT content, and try to keep the storage and transportation The environment should be kept at normal temperature and ventilated to avoid phenol yellowing.
(4) When textile and clothing produce phenol yellowing due to packaging, in order to reduce losses, you can sprinkle it on the bottom of the packaging. Add a certain amount of reducing powder, seal it in a carton and pack it for 1 to 2 days, then unpack it and leave it for 6 hours. After the smell dissipates, it can be repacked, so that the yellowing can be repaired to the greatest extent.
(5) When wearing it daily, you should pay attention to maintenance, wash it frequently and lightly, and avoid long-term exposure to the sun.
Test standard for clothing yellowing resistance
The earliest yellowing test methods are mainly Courtaulds and Marks
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After more than ten years of evolution, the internal testing method of textiles by Spencer and other companies has gradually developed into an internationally accepted method, and other different methods have been derived to test the yellowing resistance of clothing fabrics. There are many reasons for yellowing of clothing, and the testing methods are also different.
Test method for yellowing caused by natural light exposure:GB/T 8427—2008 “Textile Color Fastness test: Color fastness to artificial light: Wool standard samples were evaluated for discoloration and color fastness.
Test method for yellowing caused by ultraviolet light irradiation:GB/T 30669— 2014 “Textiles Color fastness test: Color fastness to light yellowing. The test principle is that after the sample is irradiated under ultraviolet light for a certain period of time, it is compared with the sample that has not been irradiated, and the gray sample card for evaluating discoloration is used to evaluate the discoloration grade.
Test method for yellowing caused by phenolic substances:GB/T
29778-2013 “Textiles Color Fastness Test
Evaluation of Potential Phenol Yellowing”, SN/T2468-2010 “Test Method for Phenol Yellowing of Imported and Exported Textiles”, the test principle is to sandwich each sample and control fabric in a container containing 2,6 di-tert-butyl 4-nitrophenol ( BHT) test paper, place it between glass plates and stack them together, wrap them tightly with BH-free polyethylene film to form a test package, put it into a thermostat or oven under the specified pressure.��Time. Use the gray sample card for stain assessment to evaluate the yellowing grade of the sample to evaluate the possibility of the sample producing phenol yellowing.
Test method for fabric yellowing caused by chlorine bleaching:FZ/T 01078—2009 “Fabric Chlorine absorption yellowing test method “The test principle is to compare the sample with the original sample after chlorine bleaching, cleaning and drying in a washing machine to evaluate the yellowing level of the sample.
Test method for fabric yellowing caused by atmospheric pollutants:GB/T
11039.3-2005 “Textiles – Color fastness test – Color fastness to air pollutants
Part 3: Atmospheric Ozone” The test principle is to place a sample and a control standard sample in an ozone test chamber at the same time in an atmosphere with room temperature and relative humidity, until the color of the control standard sample fades to The standards are the same. This test phase is a cycle, which is repeated until the sample reaches the specified discoloration, or until a predetermined number of cycles is reached.
Containing two test methods: natural light and ultraviolet light:QB/T 4672—2014 “Artificial Leather” Test Method for Synthetic Leather – Determination of Yellowing Resistance”, HG/T3689-2014 “Test Method for Yellowing Resistance of Footwear”.
Although there are many causes of yellowing of clothing fabrics, most of the yellowing can be removed in professional laundry . After yellowing occurs, you can try to send the clothing to a professional laundry to remove the yellowing.
