Clothing yellowing causes

Light yellowing: Light yellowing refers to the yellowing of clothing surface caused by molecular oxidative cracking reaction due to sunlight or ultraviolet light irradiation. Yellowing is most common in light-colored clothing, bleached fabrics, and whitened fabrics. After the fabric is illuminated, the light energy is transferred to the fabric dye, causing the dye conjugate to crack, resulting in light fading, and the surface of the fabric appears yellow. Visible light and ultraviolet light are the main factors causing the fading of azo dyes and phthalocyanine dyes respectively.

Phenolic yellowing: Phenolic yellowing is generally caused by the contact transfer of NOx and phenolic compounds to the surface of the fabric. The main reaction is usually the antioxidant contained in packaging materials, such as butylphenol (BHT). Clothing and shoes in the factory after a long time of packaging and transportation, packaging materials in the BHT will react with NOx in the air, resulting in clothing yellowing.

Oxidative yellowing: Oxidative yellowing refers to the yellowing caused by the oxidation of fabric by atmosphere or other substances. Textile clothing in dyeing and finishing usually use reductive dyes or auxiliaries, in contact with oxidizing gas, REDOX effect and produce yellowing.

Whitening agent yellowing: whitening agent yellowing mainly occurs on light-colored fabrics, when the residual whitening agent on the surface of clothing migrates because of long time storage, resulting in excessive local whitening agent, and yellowing of clothing.

Yellowing of softener: the softener used in the garment finishing process, when subjected to heat, light and other conditions, the cation in it will oxidize, resulting in yellowing of the soft treated parts of the fabric.

Although yellowing can be divided into the five types mentioned above, the phenomenon of clothing yellowing is usually caused by the superposition of many reasons in the actual use.

How to prevent clothing yellowing

(1) In the production and processing process, the enterprise should minimize the use of brightening agent and shall not exceed the yellowing point of brightening agent.

(2) When finishing and finalizing the fabric, the temperature should not be too high, because the high temperature will make the fabric surface dye or additives oxidize and crack, and then cause the fabric yellowing.

(3) In the process of packaging, storage and transportation, use packaging materials with low BHT content, and try to keep the storage and transportation environment at normal temperature and ventilation to avoid phenolic yellowing.

(4) Under the condition of phenolic yellowing caused by packaging of textile and clothing, in order to reduce losses, a certain amount of reducing powder can be scattered on the bottom of the package, sealed on the carton and packed for 1 ~ 2 days, and then opened and placed for 6 hours. After the smell is gone, the packaging can be repackaged, so that the yellowing can be repaired to a large extent.

(5) in daily wear, should pay attention to maintenance, frequently wash light wash, should not be long time exposure.

Standard for testing yellowing resistance of clothing

The earliest yellowing test method is mainly the internal test method of textiles by Courtaulds, Marks & Spencer, etc. After more than ten years of evolution, this method has gradually developed into an international common method, and derived other different methods to test the yellowing resistance of clothing fabrics. The reasons for yellowing vary, and the testing methods are not the same.

Caused by natural light to illuminate the yellowing test method: GB/T 8427-2008 "textile color fastness test Fastness to artificial light: xenon arc, the testing principle is to sample with a set of blue wool sample to put in the box body, in accordance with the relevant provisions under artificial light exposure conditions, the final sample with blue wool sample color rating, and to evaluate the color fastness.

Testing method for yellowing caused by ultraviolet light irradiation: GB/T 30669-2014 Test for Color Fastness to Light Yellow Color Fastness of Textiles The test principle is that after the sample is irradiated under ultraviolet light for a certain period of time, it is compared with the unirradiated sample, and the grade of color change is evaluated with the gray sample card for color change evaluation.

Test method for yellowing caused by phenolic substances: GB/T 29778-2013 "Evaluation of Potential Phenolic Yellowing in Textiles Color Fastness Test", Sn/T2468-2010 "Test Method for Phenolic Yellowing in Import and Export Textiles", the test principle is to put each sample and control fabric in a test paper containing 2,6 ditert-butyl 4-nitrophenol (BHT). Put them between glass plates and stack them together with BH-free polyethylene film and wrap them together to form a test package, and put them in a constant temperature or oven for a certain time under the specified pressure. The yellowing order of the sample was evaluated by using the grey sample card to evaluate the possibility of phenolic yellowing of the sample.

Fabric yellowing test method caused by chlorine bleaching: FZ/T 01078-2009 "test method for chlorine absorption of fabric yellowing" its test principle is the sample in the washing machine after chlorine bleaching, cleaning, drying, and the original sample comparison, in order to assess the sample yellowing grade.

Test method for yellowing of fabrics caused by air pollutants: GB/T 11039.3 -- 2005 "Textiles test for colour fastness to air pollution -- Part 3: Atmospheric ozone "its test principle is a piece of sample and a control standard sample, in the ambient room temperature, relative humidity of a certain atmosphere, at the same time placed in the ozone test chamber, until the color of the control standard faded to the same as the fading standard. The test phase consists of one cycle, which is repeated until the sample achieves a specified discoloration or a predetermined number of cycles.

Include two test methods of natural light and ultraviolet light :QB/T 4672-2014 "Determination of yellowing resistance of synthetic leather test method", HG/ T3689-2014 "Footwear yellowing resistance test method".