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Pretreatment of polyester cotton flame retardant fabric

2018-09-01 15:25 | writer: admin

Polyester cotton flame retardant fabric is a fabric made of polyester and cotton. The physicochemical properties of polyester and cotton fibers are different, but both should be considered in dyeing and finishing.
1. Singing: polyester cotton flame retardant fabric will be singeing before boiling; due to the smooth process of grey fabric singeing, easy management, general polyester cotton flame retardant fabric grey fabric singeing temperature requirements lower than 180, temperature is too high, cloth width contraction is too large, feel hard and rough, strength decline or even Brittle damage. The singeing equipment is still good for gas singeing machine. The temperature of polyester-cotton flame retardant fabric should be below 50 C after singeing, and it can be cooled by cold air or by winding large cold water rolls or by spraying. Electrostatic eliminator should be installed for dry cloth, so as to avoid falling cloth, or fabric is rolled to the falling rack.
2. Desizing: Polyester cotton flame retardant fabrics are usually paddled with PVA and its mixture, and alkali desizing can be used in desizing. Alkali desizing process with caustic soda 5-10g/L, a moderate amount of wetting agent, 80 C pad alkali after stacking 0.5-1h, hot water (80-85 C) washing, cold water washing. When washing, the amount of water should be sufficient to prevent the returned size from re-adsorbing to polyester cotton flame retardant fabric, affecting dyeing, desizing rate required to reach 80%. Sodium bromate 1-2 g/L, pH 9.5-10.5, room temperature soaking and rolling, stacking 15-20 min, caustic soda 3-5 g/L at 85-90 C, and then hot water and cold water are used to wash the oxidizing agent.
3. Scouring: When PVA is the main sizing agent, the polyester cotton flame retardant fabric can be scoured once. If starch is the main sizing agent, it should be scoured after enzymatic desizing. Due to the poor alkali resistance of polyester fiber, the scouring process should be milder than cotton fabric. The main scouring equipment is open-width steaming equipment. Rope scouring is easy to cause wrinkles. Generally, it is not used. However, a few factories use rope scouring to treat medium-thin grey fabric for printing. At present, the production tends to use hydrogen peroxide or sodium chlorite for rapid boiling and bleaching in one bath, and has achieved initial success.
4. bleaching: chlorine bleaching is only used for bleaching of dark polyester cotton flame retardant fabrics. The chlorine oxygen double bleaching process can also be used for pretreatment of medium and light colored varieties. Sub drift has strong ability to remove cottonseed hull, but does not require high boiling, but is limited by equipment. Oxygen bleaching is the most widely used bleaching method with good bleaching degree, no pollution to the environment and little corrosion to the equipment. ,
5. Mercerizing: Mercerizing is to improve the dyeing performance of cotton fiber in polyester cotton flame retardant fabric. Considering that polyester fiber in polyester cotton flame retardant fabric is not resistant to high temperature and strong alkali, the temperature of washing alkali solution and alkali removal box should not be higher than 80 C. After mercerizing washing, the alkali content on cloth should be reduced as far as possible, and the pH value should be controlled at about 7 Mercerizing equipment can be used with mercerizing machine or direct roller mercerizing machine.
6. Bleaching: The printed fabrics with large area of bleaching and polyester cotton flame retardant fabrics need to be whitened by fluorescent brightener DT after bleaching, which can be immersed, rolled and dried and fixed at the same time during heat setting. After setting, the cotton bleaching agent is added with bleaching agent VBL to bleach in the same bath, and the excess whitening agent DT can be removed at the same time.
7. Thermal setting: the main purpose is to eliminate the existing wrinkles on the polyester cotton flame retardant fabric and improve the dimensional stability of the fabric and easy to produce difficult to remove the creases. In addition, heat setting can also improve or change the strength, handle, pilling and surface smoothness of polyester cotton flame retardant fabrics to a certain extent, and also affect the dyeing performance.

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