At present, a large number of shuttleless looms with the characteristics of "large opening, small opening, strong beating-up, and high frequency of opening" have been introduced into my country, which makes the looms increasingly demanding for the pre-weaving process, requiring warp and weft yarns to have high strength. , Low strength unevenness, smooth yarn body, less hairiness, wear resistance, stretch resistance, etc., to reduce the warp and weft break of the loom, and ensure the efficient operation of the loom. How to improve the inherent quality of sizing and thus the efficiency of looms is an important task facing textile enterprises.

High-pressure sizing is beneficial to improve the quality of sizing, and is beneficial to reduce the sizing rate and increase the speed of sizing. In the high-pressure sizing process, the size should be selected according to the yarn varieties, and the process parameters should be set reasonably and the sizing operation should be set reasonably to keep the sizing rate within the process requirements. Through continuous research on the high-pressure sizing process, the efficiency of the loom can be effectively improved.

So, how to make the high-pressure sizing process work better?

The pressure of high-pressure sizing should be set according to the type of yarn

The main points of the high-pressure sizing process are high speed, high pressure and low viscosity. Generally, the pressure weighting rate is less than or equal to 100%, that is, the sizing rate/solid content rate is less than or equal to 1, as the starting point of high-pressure sizing. "Equivalent pressure pulp" refers to the setting according to the rated pressure pulp and the maximum speed of the sizing machine. Regardless of the speed of the sizing machine within the rated range, it can reach the rated pressure when the maximum speed is 100m/min. The grouting effect with a pressure of 40kN.
Under normal circumstances, the normal speed is generally 70% to 80% of the rated speed, that is, the squeezing force of this yarn type is in the range of 20kN-40kN at the normal speed, and the sizing force should be increased correspondingly if the sizing coverage rate is large. Many yarns, especially those with a large coverage rate of sizing groove yarns, such as those with thick yarn number and high warp density, the sizing speed is difficult to achieve high speed, and a large pressure pulp is required to achieve good sizing and hairiness. Clothing effect; while the sizing speed can be increased for varieties with finer yarn number and lower warp density, but the squeezing force requirement is not too high, and the squeezing force can be moderately reduced.

In production, the sizing force cannot be set uniformly, and the sizing force must be adjusted according to the yarn type and the size of the sizing coverage. The high-pressure sizing process has a wide variety of adaptability, the sizing rate is large, the sizing force should be increased correspondingly, and the sizing rate is low, so the sizing force can be appropriately reduced.

Reasonable configuration of high-pressure sizing process in high-pressure sizing

The formulation of the sizing process should be based on the warp and weft yarn density of the yarn variety, and the fiber composition analysis to formulate the sizing process and select the size. The sizing must be formulated according to the common moisture regain and blending ratio of the fiber.
Among the commonly used varieties such as pure cotton, polyester cotton, polyester, viscose, and cellulose fibers (Lyocell, Modal), hydrophobic fibers are not easy to sizing, and light-water fibers are easy to sizing, and the corresponding size selection should also be different. Special varieties such as fine-gauge yarns, high-count and high-density yarns, and varieties with large sizing coverage should consider using low-viscosity sizing agents to increase the fluidity of the size tank slurry. The yarns of Lyocell and Modal have high strength and long hairiness. The sizing should be based on matching hairiness. It is best to use less or no PVA.

For varieties that need to use PVA, the degree of polymerization of PVA must be controlled. The polymerization is too large, the serosal film is hard, it is difficult to twist, the hairiness is not good, and the hair is easy to break. In addition, it is necessary to control the degree of polymerization and alcoholysis. The higher the degree of polymerization of fully alcoholylated PVA, the lower the infiltration rate. The infiltration rate of partial alcoholysis of PVA is higher than that of complete alcoholysis. Therefore, the polymerization degree and degree of PVA should be selected reasonably. The degree of alcoholysis is very important to the sizing quality.

Reasonable control of moisture regain in high-pressure sizing
In production, whether the sizing machine is at a normal speed or a slow speed, the moisture regain of the sizing machine should not change much and should remain relatively stable.
Maintaining the moisture regain of the sizing is essential for keeping the sizing film relatively intact and reducing secondary hairiness. It also plays a key role in ensuring the clear opening of the loom and reducing noil and neps on the cloth surface. Under the condition of reasonable process setting, normal speed can ensure smooth production. Slow cars often have too little moisture regain, resulting in increased breakage in the sizing dry zone and increased hairiness, which is easy to cause difficulty in yarn separation, hairiness entanglement, and even end breakage.

Sizing and slowing will cause the corresponding sizing shaft to appear up and down during weaving, and sometimes there are neps, resulting in large fluctuations in the efficiency of the loom. When manually controlling the slow car, such as stranding, full axle, and cutting, the warp beam is wrapped around the yarn. Before closing the car, close the dryer valve in advance to control the moisture regain of the slow car above 6%.

The low moisture regain of sizing has a great influence on hairiness, especially the Lyocell and Modal varieties. When the moisture regain is low, the sizing noil increases greatly after the yarn comes out of the drying room. Only when the moisture regain reaches the technological requirements, this phenomenon will not appear. In production, some companies have unreasonable design of the sizing machine process, which prevents the sizing machine from tracking correctly.

After setting the process of squeezing force, vehicle speed, and moisture regain, the process requirements are not met after the start-up operation. This is because the main and pre-drying cylinders are set at too high temperature and exceed the tracking range and are not suitable for this variety. Claim. Therefore, a reasonable setting of the sizing process can give full play to the automatic tracking effect of the sizing machine.

The selection of sizing moisture regain should be based on the common moisture regain of the fiber and the fiber ratio. At the same time, the sizing speed should be controlled. If necessary, adjust the drying and pre-drying temperature settings of the drying house to achieve the process moisture regain. Ensure the stability of the moisture regain of the sizing process.