Dyeing and finishing process of polyester products
Through people’s continuous improvement of polyester fiber, polyester The products have become more and more popular among everyone. Polyester is widely used in knitting, home textiles, industrial and other industries, and the demand is very broad.
The technological process of ordinary polyester (low twist or medium twist) fabrics:
Prepare fabric → pre-treatment and bleaching (whitening) ) → washing → dehydration → drying → shaping (finishing) → inspection and packaging
The process flow of ordinary polyester (high twist) fabrics:
Prepare fabric → Pre-shrink → Book → Reduce → Pre-treatment and bleaching (whitening) → Washing → Dehydration → Drying → Shaping → Inspection
Process description
1. Fabric preparation: select, weigh and sew the gray fabric.
2. Preshrinking: Preshrinking is required when processing 100% polyester twisted fabric, and the preshrinking process is completed in the dyeing equipment. The preshrinking temperature of strongly twisted fabrics is higher than that of elastic fabrics, which can reach 130°C. Refining agents can be appropriately added during pre-shrinking to remove various impurities on the fabric. However, if the temperature is too high, the refining agent added during pre-shrinking will easily peel off the magazines on the inner wall of the dye vat, causing contamination to the fabric and ultimately affecting the whiteness. In order to improve the impurity removal effect in the pre-shrinking stage, an appropriate amount of liquid caustic soda can be added during pre-shrinking.
3. Predetermination: The temperature of strongly twisted fabrics is slightly higher, generally not exceeding 200°C. The determination of the vehicle speed is not only related to the thickness and moisture content of the fabric, but also related to the length of the setting machine.
4. Weight reduction: The scheduled weight reduction of strongly twisted fabric can be completed in the weight reduction machine or in the weight reduction cylinder. The intermittent rope reduction of the reducing machine facilitates the control of fabric feel and strong damage. When reducing the amount, a reduction accelerator can be added appropriately.
5. Pre-treatment and bleaching: Bleaching and whitening of ordinary polyester fabrics usually takes one bath. Temperature﹤130℃, holding time 40min.
6. Washing: It is best to add an acid wash before the fabric comes out of the vat to ensure the feel of the fabric. Ordinary washing can also be performed.
7. Drying: usually the padding and tenter drying method is used, the temperature is controlled at 160-180℃, and the time is 30-60S. It can also be dried directly.
Precautions when dyeing polyester fabrics:
Strongly twisted fabrics require weight reduction processing and bleaching and whitening processing. The temperature of the fabric can be increased during refining, and the bleaching and whitening process can be completed in one bath. When dyeing polyester fabrics, the temperature is generally controlled at 110-130°C. Generally, at 102-110°C, dye aggregation is likely to occur. If the aggregation is absorbed by the fiber, stains will easily occur, so the temperature must be raised quickly at this temperature.
Precautions for pre-processing of polyester fabrics:
1. Gray fabrics should not be stored for too long to avoid damage to the fabric. Uneven internal stress affects the stability of door width dimensions.
2. The temperature is controlled below 200℃ during preforming.
3. When bleaching and whitening, the heat preservation time can also be appropriately extended and the process temperature can be raised.
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