Knitted fabrics of several technical knowledge

Heat setting of stereotyped fabric can be divided into dry and wet
Dry heat setting:
The fabric is heated in the heating chamber by hot air, the sealing degree is pulled to a certain size, after cooling out of the heating chamber, so that the temperature is reduced to the glass transition temperature of the fiber, so as to obtain a stable size, such as polyester fabric, the temperature is generally 180~~210 °C, time 20~~30 seconds.
Hot and humid setting:
There are hot water baths and steaming. Hot water baths treat the fabrics in boiling water or high pressure cylinders. Steaming winds the fabrics around a perforated roll and steam steams them. Nylon fabrics are usually damp heat set at high pressures. Cylinder with a temperature of 125 ~ ~ 135 °C, processing 20 ~ ~ 30 minutes.
Heat setting can make the fabric size stable at a certain degree, and set the pre-tension of the program control system, wash the water after the finished product, or dry by mechanical force, etc., and eliminate the tension of the set shape, then restore the pre-setting. Size, the rate of change in this process, is known as shrinkage, and includes both straight and horizontal changes.
The shrinkage rate has negative and positive values, while the area shrinkage of the fabric indicates the rate of change of the area of ​​the fabric in the transverse and straight four points, which is also equal to the sum of the transverse and straight shrinkage rates minus its product, if the shrinkage rate of the area is low. At 10%, the area shrinkage is approximately the sum of the shrinkage of the straight and horizontal. The shrinkage rate of the fabric is a raw material, and the method of fabric organization and processing is different, and there are differences. It is somewhat difficult to judge the recovery force of the fabric by the shrinkage ratio of the horizontal and vertical directions. Only the dimensional change of each process of the fabric dyeing and finishing process is observed. Make a decision.
To control the fabric in the pre-shrink to a certain extent, the residual shrinkage in a certain degree of control, this process is an important part of finishing processing.
Mechanical shrink-proof finishing:
In order to achieve the above conditions, the mechanical manufacturer designed a mechanical shrinking machine that uses compression to force the fabric to shrink in the lengthwise direction and increase the weft density, so that the fabric has a slack structure, which can reduce the shrinkage of the finished product. The mechanical shrinking machine uses a blanket or The rubber blanket maintains proper tension and circulates, the amount of fabrics is fed in, and the fabric needs to contain a certain humidity. It is then fed between the hot roller and the rubber blanket so that the horizontal and vertical space is compressed and the length of the fabric is changed. Short, the structure of the fabric is fixed by the moist heat effect.
Before pre-shrinking, the fabric needs to be wet to increase the flexibility of the fiber, and the compression is controlled in the thickness of the blanket and the size of the curvature. After this process, the shrinkage of the fabric rewash can be reduced to 1%, and the hand feel is also better. The method of controlling the shrinkage rate must be carried out in various ways in order to obtain the desired results.
(1) Whether the specifications set by the fabric meet the basic requirements.
(2) Changes in yarn type and shrinkage.
(3) During the processing of fabrics, it is necessary to minimize the tension to which they are subjected.
(4) Use pre-shrinking machinery to relax the internal stress of the fabric.
(5) Using a resin finishing method to reduce the hydrophilicity of the fiber and then stenting.
(6) The use of mechanical shrinkage plus resin finishing combined treatment.
(7) The use of pull side vibration dry cloth machine, that is dyed or bleached fabric out of the cylinder, in the wetting state of the cloth, and then use the pull edge vibration wave dry cloth to pull the dry cloth, and then through the shrink machine to stabilize its product specifications. Because the fabric has been subjected to straight-line tension during processing, the horizontal stretcher of the wave machine is used to make up for the straight stretch caused by the dyeing or bleaching process. After shrinking by the wave machine, the shrinking machine then passes through the shrinking machine. The mechanical forced retraction, so as to achieve the average straight-line shrinkage. Fabrics of different organizations can also be specified to control the setting of the tenter, so that the shrinkage rate can be controlled, overfeeding can reduce longitudinal shrinkage, and the width of the chain rows on both sides of the stenter can be adjusted to control the lateral shrinkage.
The current shrinking problem has caused the entire bank to pay great attention. In addition, many companies have abandoned certain types of fabrics instead of replacing the setting machines with pre-shrinking machines, and have used dry cloths with needles to control the size of the fabric while dry cloth is being used. Pre-shrinking machine reduces shrinkage. The fabrics of different organizations can also be specified after the finishing process, for example: the general past process, that is, weaving → dyeing → dehydration → dry cloth → open width → stereotypes, the new process is: weaving → dyeing → wet cloth opening → pull side vibration Wave Dryer → Over Shrinker. When the production process changes, the specifications should be changed and adjusted accordingly, a variety of different processes, the purpose of the fabric shrinkage as much as possible.

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