Styling is the main process of finishing. Through the mechanical action of the setting machine and the anti-shrinkage, softening, and hardening effects of chemical reagents, knitted fabrics can achieve a certain shrinkage, density, and feel, and can achieve the appearance of uniform width, smooth lines, and clear textures. . The following describes the practical technology of shaping and finishing
Styling and finishing production
Styling machine It is a machine used for shaping textile products. The shaping machine can be divided into yarn shaping machines, sock shaping machines, fabric shaping machines, curtain shaping machines, spandex covered yarn shaping machines, silk shaping machines, garment shaping machines, and suit shaping machines. Machine and so on.
Heat setting of stereotyped fabrics is divided into two types: dry and wet
Dry heat setting:
The fabric is heated by hot air in the heating chamber, and the sealing degree is stretched to a certain size. After leaving the heating chamber, it is cooled and the temperature is reduced to the glass transition temperature of the fiber. In order to obtain stable dimensions, such as polyester and other fabrics, the temperature is generally 180~~210℃ and the time is 20~~30 seconds.
Moist heat styling:
There are two options: hot water bath and steaming First, hot water bath is to process the fabric in boiling water or a high-pressure cylinder, while steaming is to wind the fabric on a perforated roller and steam it with steam. Nylon fabric is commonly used for moist heat setting, and the temperature is 125~~135 in a high-pressure cylinder. ℃, process for 20~~30 minutes.
Heat setting can stabilize the size of the fabric to a certain set level, and the setting is done through program-controlled pre-tension, washing after the finished product, or mechanical force, etc. After drying, pre-setting and tension elimination, the size will return to the size before setting. The change rate during this process is called shrinkage, including vertical and horizontal changes.
Fabric parameters related to styling
1. Representation of yarn thickness Method
Indicates the thickness of yarn, which can be divided into imperial count and metric count. The commonly used imperial count (Ne) indicates how many 840 yards are contained in each pound of yarn. For example, 8S/1 means that each pound of yarn contains eight 840 yards. Metric count (Nm) refers to the length of yarn in meters per gram of weight. It can be seen from the definition that the smaller the yarn count value, the thicker the yarn. The units that indicate yarn thickness include denier and special number. Denier (D) refers to the grams of yarn per 9,000 meters; Tex (Tex) refers to the grams of yarn per 1,000 meters. It can be seen from the definition that the larger the denier (special number) value, the thicker the yarn. The British and metric counts are called fixed-weight units, and the denier and special numbers are called fixed-length units.
2. The meaning of some knitting process parameters
1. CPI : The longitudinal density of the fabric, that is, the number of coil courses (modulus) within 1 inch along the longitudinal direction of the coil;
2. WPI: The transverse density of the fabric, that is, the number of coil courses within 1 inch along the transverse direction of the coil Number of coil columns (number of needles);
3. Gram weight: weight of fabric per unit area (GM/M2);
4. Yarn length: Generally expressed as 50C, which is the length of 50 coils. Measured in MM.
Physical indicators and methods of stereotype control
1. Door width
The door width can be adjusted directly on the shaping machine during production. The adjustable door width on the shaping machine is in centimeters, but the company’s order requirements generally require that the door width be in inches. Therefore, during the production process, inches must be converted into centimeters before adjustment can be made. Conversion formula: 1 inch = 2.54 centimeters.
2. Gram weight
Generally, the gram weight is Controlled by adjusting overfeeding. Under the condition that the other tensions remain unchanged, within a certain range, the greater the overfeed, the heavier the gram weight, and the smaller the overfeed, the lighter the gram weight.
3. Cycle
Cycle is closely related to gram weight , refers to the repeated size of the pattern from the starting point to the end point. Its control method is the same as that of gram weight. Typically, cycling is controlled by adjusting overfeed. When the remaining tension remains unchanged, within a certain range, the larger the overfeed is, the shorter the cycle will be, and the smaller the overfeed will be, the longer the cycle will be.
4. Shrinkage
Shrinkage is the most important thing to control when styling One of the physical indicators. The shrinkage must be even and reasonable to be OK. For styling, shrinkage is mainly controlled through resin or pre-shaping.
For pure cotton fabrics, resin is generally used to control shrinkage. When the resin can fully react, the greater the amount of resin, the better the shrinkage, but the problem that arises is that the strength decreases more. Therefore, the amount of resin is subject to certain restrictions. Under normal circumstances, B/F strength is >85PSI, the test method is TUMBLEDRY fabric type, and the resin dosage is 50G/L. Generally, a formula with a resin dosage of 50G/L is regarded as a complete material. For pure cotton double-sided fabrics that only undergo ordinary finishing, the resin dosage of 80G/L is regarded as the entire material. Test methods for LINEDRY, HANGDRY, and FLATDRY generally reduce resin production to save costs.
5. Twisting
Due to the twisting of the yarn, the yarn After the thread is woven into fabric, it has a certain tendency to twist back, forming a twist. The tendency to twist is more pronounced in single-sided fabrics.
The size of the distortion is related to the twist of the yarn itself, the fabric structure and the knitting process. Distortion is generally controlled by oblique shaping or step-by-step shaping. In many cases, two methods are also used.The structure has a significant impact, and there is a close relationship between fiber structure and performance. Therefore, it is important to pay attention to tension control during any shaping process.
4. Is there any swelling agent on the fabric during heat setting? The presence of swelling agents has a certain relationship with the setting effect. Commonly used swelling agents are actually water or steam. For example, the presence or absence of moisture has a significant impact on the dyeing properties of nylon.
Compared with unset fibers, the diffusion rate of dyes in steam-set fibers increases, but decreases in dry-heat-set fibers.
The increase in the dye diffusion rate in the fiber after steaming and setting is not due to the increase in solution orientation or end groups from the fiber structure, but because of the formation of another fiber. caused by a supramolecular structure.
Figure 2-1-9 compares the NMR test results of the fiber after heat setting of nylon 6 under dry heat and wet conditions. It is known that the NMR test can detect large fluid-like movements in the fiber. The content of molecular chain segments.
It can be seen from Figure 2-1-9 that water has a “loose” fiber structure, reinforcing macromolecular segment fluids The effect of general movement is obvious even at room temperature.
This illustrates the plasticizing effect of moisture during the heat setting process, thereby affecting the supramolecular structure and physical properties of the fiber. In addition, if you want the fibers to have the same crystallinity after being set, during steam setting, due to the effect of moisture, the temperature can be lower than that of dry heat setting. Moreover, from the perspective of water absorption, their amorphous zone structure also has The difference is that the water absorption capacity of the fiber after steaming and setting is much higher.
During moist heat setting, tension also has an impact on the structure and physical properties of the fiber. Tension has the opposite effect on “loose” fiber structure.
The influence of moisture on the properties of polyester during heat setting is small, and is far less obvious than that of nylon. </p