Synthetic fiber filament is composed of multiple single fibers, such as 165dtex/48f, which means that 48 single fibers are combined into a 165dtex multifilament. During the production process, the filament must go through the entanglement under stress. , doubling, twisting, shaping and other processes. During the weaving process, they have to undergo repeated friction from guide rollers, healds, and reeds. The friction of the silk threads can be more than 10,000 times. The speed of the water-jet loom during weaving is generally 500~700r/min, high-speed friction monofilament is very easy to fluff, which not only affects the weaving efficiency, but also seriously causes the inability to weave, and significantly reduces the quality of the product. For this reason, untwisted or low-twisted synthetic filaments must be processed Sizing. After sizing, the warp yarns can withstand the friction during processing and weave smoothly, and the quality of the product is guaranteed.
The mechanism of sizing is: after sizing, the slurry forms a layer of sizing film around the silk body to withstand the friction of various equipment; and the slurry penetrates into the single fibers, The single fibers are glued together to improve the cohesiveness and strength of the multifilament, thus ensuring that the fibers can successfully complete the tasks of subsequent processes. Due to the high hairiness of staple fiber yarns, the sizing effect requires that the material be mainly covered, while the sizing of synthetic filament yarns requires mainly penetration and supplemented by covering. Since the moisture regain rate of synthetic fiber yarns is low, for example, the standard moisture regain rate of polyester yarn is 0.4%, and that of nylon yarn is 4%. They are hydrophobic fibers, that is, they are not compatible with water, so their sizing is not as easy as viscose yarn. It must meet two conditions: that is, the viscosity of the slurry must be very good, and the slurry can stick the single fibers to each other when it penetrates into the single fibers, ensuring satisfactory bundling and forming a good slurry film around the filament body. , to ensure its good wear resistance. When sizing the yarn, it is necessary to ensure that there is a certain distance between the sizing yarns to prevent the sized multifilaments from sticking to each other and failing to weave.
When sizing, the slurry preparation and sizing process must be strictly controlled. At present, domestically produced slurries mostly use acrylic ester, and the quality is generally passed. However, strict selection must be made, especially the viscosity and concentration should meet the requirements, and blind purchase should be avoided. In order to prevent the antistatic agent on the silk from being removed during the sizing process, an appropriate amount of antistatic agent should be added to the slurry. In order to maintain the softness of the silk thread, a certain amount of softener can be added, as well as an appropriate amount of penetrating agent and defoaming agent. During the pulping process, the prescribed pulping operating procedures must be strictly followed so that the pulp meets the production requirements.
In production, it is necessary to strictly follow the requirements of the sizing process and achieve “seven fixes”, namely, fixed slurry viscosity, fixed slurry concentration, fixed slurry temperature, fixed sizing linear speed, fixed sizing The elongation of the sizing yarn, the moisture regain of the sizing yarn (the temperature of the drying cylinder or drying chamber), and the sizing rate are determined. Viscosity indicates the degree of viscosity of the slurry, while concentration indicates the amount of solid glue contained in the slurry. Generally speaking, the two are in line. However, due to the different qualities of each slurry, even slurries of the same concentration will The viscosity is also different, so strictly speaking, both must be controlled. In daily production, some people often only control the viscosity, while others only control the concentration.
The higher the viscosity and concentration of the slurry, the stronger the filament strength and surface wear resistance will be, and the lower the elasticity, the easier it will be for the filament to be brittle and broken, and there will be more slurry, so it must be controlled correctly. . The sizing line speed is too fast. Although the production efficiency is high, the quality of the sizing yarn becomes poor due to insufficient penetration of the yarn and poor coating. During the sizing process, the warp yarns generally show an elongated state due to being pulled by rollers, sizing rollers, drying cylinders, etc. However, polyester, nylon and other synthetic filaments are heat shrinkable fibers, and the yarn body passes through the sizing tank, drying cylinder and heat. The slurry in the drying chamber will shrink, so the sizing rate of synthetic fiber yarns is generally offset by the stretching and shrinkage. The elongation is about 0, the slurry stretches, the fiber body is stretched, the strength is affected to a certain extent, and it is easy to break, but the sizing If the stretch is small, the silk body will be stretched by the tension of the machine during weaving, destroying the serous film, and the fiber will easily fluff. The moisture regain of slurry yarn is high, and the yarn body is prone to sticking, and the yarn shrinks unevenly, resulting in loose warp, insufficient hardness, and in severe cases, shaft cracking. However, if the moisture regain is low, static electricity is easily generated, causing fiber fluffing, and Because the serous film is hard and brittle, the serous liquid in the silk body has good permeability and the sizing quality is good. However, if the sizing rate is too high, sizing will occur and even weaving cannot be achieved. If the sizing rate is small, the silk fibers will easily become hairy. Therefore, it is necessary to explore the best sizing process from production practice and implement it effectively. This is an important measure to ensure the quality of slurry and product.
At present, the automation control technology of fiber sizing machines is relatively high. Just input the required process parameters into the computer monitoring system, it can be automatically controlled and detected online. The image can also be displayed on the infrared touch screen and automatically recorded. The important thing here is that the technician needs to enter the correct process parameters and press the recorded data. Correct the process parameters in a timely manner according to the actual production conditions.
Which raw materials can be woven directly without sizing?
Weaving raw materials can be divided into two categories: warp raw materials (threads) and weft raw materials (weft wires). Generally speaking, weft yarn raw materials can be used directly on the machine without any processing and treatment in water-jet weaving. After unpacking, the warp yarns are repeatedly pulled by healds, steel reeds, etc. during the weaving process. Stretching, friction and bending will cause a decrease in the mechanical properties of the warp filaments, easily causing fibers to be scattered, rubbed, etc., resulting in warp breakage.So as to affect the smooth progress of weaving. Therefore, when using untwisted or low-twisted synthetic filament as warp yarn, it must be sizing to improve its weaving performance, so as to adapt to the high-speed operation of the loom and ensure smooth weaving.
So, which warp yarn raw materials can be woven directly without sizing?
According to the requirements of the fabric and the supply of raw materials, size-free yarn can be used as the warp yarn and directly woven. Sizing-free yarn refers to a type of warp yarn raw material that can be directly woven and produced without sizing treatment. The English abbreviation is NOY or NSY.
Sizing-free silk mainly includes the following types:
1 Network yarn
Also known as intertwined yarn, the multifilament yarn is blown by compressed air in the network nozzle, so that some fibers are locally entangled with other fibers at intervals without intertwining. Loose, thus forming strands with a network of points. When the multifilament passes through the network nozzle at a certain tension and speed, it is blown by compressed air in a vertical direction or at a certain angle, causing the single filaments in the multifilament to vibrate strongly, causing dislocation, bending and other single line entanglements, producing periodic Locally entangled network points increase cohesion and can replace twisting. When weaving network yarn, it is not easy to cause hair breakage. Network yarn with a network point of more than 150/m can be woven directly without sizing. Sizing-free yarn mainly refers to network yarn (interlaced yarn). But if the network is too high, the refractive index of the fabric surface will be uneven, affecting the appearance and feel. To improve its weavability, oiling (waxing) or appropriate sizing (light sizing) can be performed during warping, which makes it more suitable for high-speed water-jet looms.
2 Twisting the silk
Twisting the silk, generally When the twist reaches 6~8 twist/cm or above, sizing is not required during weaving. However, the number of processing steps increases, the cost increases, and sometimes the quality of the product is affected. In water-jet weaving projects, except for varieties that require warp yarns to be twisted, twisted yarns are generally not suitable.
3 Reduce the number of single filaments in synthetic filaments
Filament yarn fabrics require a smooth, plump silk surface and a soft hand feel, so when selecting raw materials, it is often desirable to use multifilaments with a larger number of monofilaments combined. For example, 77.8dtex (70 denier) nylon yarn is composed of 16, 18, 36, 48 and other single filaments. This kind of synthetic filament often needs to be sized before it can be woven on the machine. If methods such as reducing the number of monofilaments of multifilaments and thickening the diameter are used, such as when the number of monofilaments of the above-mentioned nylon filaments is reduced to less than 10, there is no need for sizing, as long as the warp is treated with oil or wax during warping. The shaft can be put on the machine for weaving. However, this method will harden the feel of the fabric and have poor appearance due to the reduction in the number of single filaments or the increase in diameter. This method is especially important for polyester filament fabrics, so it is difficult to adopt.
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