Washing process is the most unique processing method for denim clothing, and it is also a high-risk stage for fabric and finished clothing to break or lose elasticity. The main reason is that most washing enterprise personnel do not attach importance to the inspection of raw materials and are not familiar with fiber composition, fabric structure, etc. In order to ensure quality, when determining the washing process, it is necessary to analyze the fiber composition and fabric structure of elastic denim clothing, select appropriate dyeing and chemical additives based on the washing effect of the clothing, set the optimal washing process, and conduct washing sample experiments. After the experiment is passed, mass production can be arranged.
The determination of washing process should be managed from the following two aspects:
(1) The polyester spandex in elastic denim clothing is not alkali resistant. When undergoing desizing and washing or processing under alkaline conditions, it is necessary to prevent the spandex from losing weight and elasticity due to prolonged use of alkali or high temperature; In addition, after processing, attention should be paid to cleaning thoroughly to prevent spandex from being damaged by prolonged exposure to alkali and causing fabric loss of elasticity.
(2) Polyether spandex in elastic denim clothing is not resistant to chlorine, and sodium hypochlorite (commonly known as bleach) can cause significant damage to the spandex's elasticity during washing. Therefore, it is advisable to avoid using bleach to wash elastic denim clothing. If it is necessary to rinse with bleach, three points should be noted during production:
① It is prohibited to directly add high concentration bleach into the washing machine. The concentration must be prepared according to the washing process requirements and then injected into the washing machine in batches; In order to prevent the loss of elasticity caused by excessive local concentration, it is necessary to add float water under the condition of equipment rotation.
② After drifting, in order to prevent the sharp drop in temperature from causing the spandex to become brittle and lose its elasticity, it is necessary to drain water while entering the water to gradually lower the water temperature.
③ Pay attention to the cleaning and rinsing of elastic denim clothing after bleaching to prevent residual bleaching water on the clothes, as the release of chlorine in the bleaching water during high-temperature drying can lead to the degradation of spandex.
For (1) and (2), there are currently some spandex protectants in the additive market. Enterprises can add them to the sample to test their protective effect, but also consider the compatibility between other washing process additives to prevent other quality problems.
(3) The enzyme powder used during fermentation washing is a multi-component complex, and its different chemical components can cause spandex to lose elasticity. Therefore, the type, amount, washing temperature, and washing time of the enzyme powder should be determined through pre production samples Process conditions such as pH value; Strengthen the management of online workers during the production process to ensure the implementation of the process.
(Acid loss and elasticity are caused by the outer layer of elastic fibers being usually cotton fibers or other cellulose fibers. Cellulose fibers are prone to decomposition under acidic conditions. Once the outer layer of fibers decomposes, spandex will be exposed and easily damaged, leading to loss of elasticity. Equipped with anti loss of elasticity and anti dyeing powder can prevent loss of elasticity caused by excessive acidity.)
(4) Elastic denim clothing requires a soft feel, and softeners, silicone oil, and other chemicals are often used. Some contain small amounts of solvents, which can damage the elasticity of spandex. Therefore, when selecting materials, attention should be paid to selecting softeners and silicone oil that do not affect the elasticity.
(5) When drying elastic denim clothing, the commonly used hanging drying method by washing companies is used first, and then a drying machine with a temperature below 60 ℃ is used to avoid damaging the spandex elasticity due to excessive temperature.
(6) When drying elastic denim clothing in a resin finishing oven, it is necessary to ensure the normal operation of temperature control, temperature measurement, and blowing devices around the equipment to avoid local high temperatures damaging the spandex elasticity.
(7) When washing water with ozone, the suitable ozone treatment time for polyether spandex is within 30 minutes, and the moisture content should be controlled at around 60%, The pH value should be controlled between 5-7 to prevent fiber breakage and loss of elasticity.
(8) When laser washing water, attention should be paid to the structure of the yarn, yarn count, and twisting uniformity to determine the appropriate laser emission intensity, in order to prevent direct damage to spandex by laser or high temperature damage to spandex, causing fabric loss of elasticity.
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