How is cotton fabric dyed?

Cotton fabric dyed processes

The whole cotton fabric dyeing should go through four technological processes: pre-treatment, dyeing, post-finishing, and finished product inspection:

1. Pre-treatment part:

(1). turn the seam and pay attention to the joint of the cloth to wrap the edge because the following process is long car production; the consequence of not wrapping the edge is if the joint of the cloth in the production process is broken in the steam box, it is very troublesome.

(2). Desizing, remove the slurry on the warp yarn when weaving; thin fabric directly de-sizing machine can be removed; after the heavy and elastic material had better choose the method of cold pile de-sizing; enzyme desizing will be more thorough.

(3). Singed wool, cotton needs to be roasted wool to remove the yarn on the length of the hair, thin cloth fire on the line, thick such as 7*7 yarn card needs to add iron plate (also called cylinder) to burn fresh.

(4). Shaping, pre-treatment shaping is only for elastic cloth. The door size is different after the fading pulp and sintering; less than the finished door size can be shaped; pre-treatment shaping can not be greater than the finished door; it is best to be close to and equal to the finished door.

(5). Bleaching, as long as the whiteness is unified, cotton fabric generally uses hydrogen peroxide bleaching, also called oxygen bleaching.

(6), mercerization, mercerization should pay attention to the width of the door; if the width of the mercerization is too small, do not open; after finishing is not open, too large, back and do not shrink back, mercerization is best controlled and finished door width consistent, so that when dyeing will shrink some, after finishing in the open, pre-shrinking control.

2. Dyeing part:

Cotton fabric dyeing is now dominated by long car continuous rolling dyeing, and cylinder dyeing is no longer the mainstream, which will not be introduced here.

Dyeing is a simple process because only one mill can be used. Still, it is also the most challenging process because of the color control of dyeing. In addition to the known, there are many unknown things on the inside, such as the stability of the dye at different temperatures, the control of steam, the power of the rolling pressure, etc., which is excellent work. The dyed long car is divided into two parts, the front vehicle is dyed, and the rear car is fixed. The dyeing method is different according to the variety of dyes selected. The shades are generally active, silly, vulcanized, and painted. They have their advantages and disadvantages, under normal circumstances, depending on the color of the guest, and can not be replaced with each other; among them, shilin's color fastness is the best, but the price is expensive, not suitable for dark, light color is not bright enough. 

In addition, dyeing dark will increase the cost; dyeing unclear relative reactive dye teaching is difficult to control, easy to appear cloth flowers and other phenomena. The color fastness of the activity is worse than that of Shilin. Still, the light color is more gorgeous, the dark color is easy to control, and the cost is correspondingly less. The worst vulcanization and color fastness could be better; AZO must be up to standard. Still, now there is liquid vulcanization (also called water vulcanization). AZO can be up to par, but the price is close to the shilling; dyeing is not easy to control and needs to be popularized. Only a few people pursue its fading effect and use. The paint is not comparable; its discoloration is severe, and it is the best choice for clothing after washing the pursuit of the discoloration effect. It can be flexibly applied with Shilin and active to obtain different washing effects (general shilin or active base, coating set color, can solve the white point problem of single dyeing coating, and the cost increases accordingly).

The activity, neroli, and vulcanization of the stain before the car are the same; say the difference is the infrared pre-baked one group, two groups, or not open. The rear vehicle is entirely different. The active use of salt and soda solid color, hydrogen peroxide reduction solid color (so Shilin is also called VAT dye), vulcanization is to high temperature cooking solid color, the water temperature must be above 95 degrees. After dyeing the paint according to the color fastness of the fading requirements, decide whether to bake the color fixation. The baking temperature is about 195-210 degrees. Dyeing is not 100% good; repair and stripping colors are inevitable. Minor adjustments, such as shallow coat deep wash with soda ash.

3. After finishing part:

Because the cotton fabric has passed a lot of long car in the pre-treatment and dyeing, the warp is elongated. Weft contraction, feel is rough, after finishing is to solve these problems. Soft and stretchy, soft and stretch, if there is no setting machine, should be carried out separately, quiet first, to improve the feel in the space. Pull the constricted weft apart. A setting machine can be done in one go. But the elastic cloth is best to finalize the process. Pre-shrink, pre-let the elongated cloth part of the production process through the rubber blanket of the pre-shrink machine, the principle of thermal expansion and cold shrinkage of the cloth to the clothing cutting allowed range, elastic cloth control in 3%, 5% latitude. The inelastic regime is on the line at 3% longitude and 3% latitude.

After finishing According to the requirements of customers, we should pay attention to whether the twill needs to be pulled, whether the weft skew of plain weave reaches the standard (the weft skew of general simple cloth should be controlled within 3%, and whether the weft skew of gingham should be controlled close to 0), and whether the weft needs to be rounded.

Factories can also, according to their equipment, but also can air soft washing fabrics. Of course, there is an additional cost.

4. Inspection of finished products:

After finishing, the cloth was tested. The customer requires the shrinkage rate, color fastness, and other internal indicators to pass the color index. It can be inspected for the finished product. General customers identify more with the United States' four-point standard inspection (China's national standard is similar, but the defects are too delicate and difficult to remember and use). The review of qualified products can be packaged.