The quality of air temperature and humidity control and regulation in the workshop directly affects the output, quality, consumption of products and the physical and mental health of employees. Air conditioning should be able to meet the temperature and humidity requirements of textile fibers during processing, ensure the normal production process of each process, and improve product quality. and equipment utilization.
Effect of temperature and humidity on cotton fiber spinning performance
There are many hydrophilic genes (-OH) in the macromolecules of cotton fiber, which has good hygroscopicity. The standard moisture regain rate of cotton fiber is 8.5%. The temperature and humidity of the air directly affects the moisture absorption and release state of cotton fibers. When the amount of moisture absorbed is equal to the amount of moisture released, the moisture absorption equilibrium state is reached. Cotton fiber can reach the equilibrium state after 6 to 8 hours in a normal environment.
The relative humidity in the workshop has a great influence on the spinning performance of the fiber. When the relative humidity increases, it can promote and improve the orderliness of long-chain molecules and increase the strength of the cotton fiber. Under standard temperature and humidity conditions, the strength of the cotton fiber is comparable to that of the dry state. Increased by 50%. However, when the relative humidity exceeds 80%, the strength increase rate of cotton fiber decreases, and even tends to decrease. Temperature has little effect on fiber strength. Generally speaking, when the temperature is high, the motion energy of fiber molecules increases, which weakens the attraction between fiber molecules in certain areas, thus reducing the tensile strength. Experiments have shown that when the temperature increases by 1°C, the fiber The intensity is reduced by approximately 0.3%.
The cotton wax on the surface of cotton fiber has a protective effect on the fiber and is one of the reasons why cotton fiber has good spinning performance. The cotton wax in the fiber becomes hardened when the temperature is below 18.3°C, the lubrication effect is reduced during spinning, and the drafting resistance increases. When the ambient temperature exceeds 27°C, cotton wax begins to melt and become sticky, which also has a negative impact on spinning drafting. Only when the production environment temperature is between 18.3 ℃ and 27 ℃, the cotton wax is in a softened state, the fiber is smooth and soft, and the spinnability is optimal.
Temperature also affects the conductivity of fibers. Generally, as the temperature increases, the conductivity of fibers also increases accordingly. However, when the temperature is too high, the cotton wax melts, causing adverse consequences of winding rubber rollers and rollers. When the relative humidity increases from 20% to 60%, the conductive performance of cotton fiber can be increased by 4 times; when the relative humidity is lower than 45%, a large amount of static electricity is easily generated and difficult to dissipate.
In the textile production process, if the temperature is too high or too low, it will easily cause the cotton fibers to break, generate static electricity and affect the drafting process. High or low relative humidity will also cause an increase in lint fly and a decrease in yarn strength. Therefore, choosing the appropriate temperature and humidity based on the physical properties of cotton fiber is the prerequisite for spinning high-quality yarn products.
Effect of temperature and humidity on product quality during production
01 Effect of temperature and humidity on blowroom and carding unit
Xinjiang cotton and imported cotton have low moisture regain (generally below 6%), which makes it difficult to meet the production process requirements of the cotton cleaning process. Short lint increases more, so the raw cotton must be pre-bulked and humidified before production to make the raw cotton The moisture regain rate is increased to more than 7.0%, which is beneficial to improving fiber strength and reducing fiber breakage during the carding and carding process. Production practice shows (see Table 1) that if the moisture regain of raw cotton is too low, the growth of card sliver linters will be greater. When the moisture regain of raw cotton reaches more than 7.5%, the growth of card sliver linters will basically stabilize. Therefore, the relative humidity of cleaning cotton should generally be controlled at 60% to 65%, and that of carding should be controlled at 50% to 55%, so that the fibers are in a dehumidifying state of dry outside and wet inside during the production process, thereby enhancing the softness and impact resistance of the fibers. ability. The moisture regain of raw cotton in the cleaning process is too small, the cotton fibers are fragile and easily broken, the waste increases, and the increase in short lint will directly affect the strength of the yarn. If the moisture regain is too high, it is not conducive to loosening and impurity removal, and the fibers are prone to bunching. If the relative humidity of carding is too high, carding will be difficult, neps will increase, impurity removal efficiency will decrease, and ends will break. If the relative humidity is too low, fibers will be easily broken and noil will fly. The moisture regain rate of raw strips is generally controlled at (6.5±0.5)%.
Table 1 Short staple ratio of card slivers generated under different raw cotton moisture regain conditions
02 Effect of temperature and humidity on combing
In the drawing process, cotton fiber first moisturizes and then absorbs moisture, and the moisture regain rate should be controlled at (6.8±0.5)%. The relative humidity of pre-drawing is required to be between 65% and 70%. At this time, the fiber is in a hygroscopic state, which can increase the friction factor on the fiber surface to ensure that the rollers hold the fiber and draw force during the drawing process, thereby improving the fiber’s strength. Parallel straightness, the straightening and parallel conditions of fibers under different temperature and humidity conditions are shown in Table 2. The combing process has high requirements on temperature and humidity. Generally, the moisture regain rate is required to be maintained at 63% to 68% to keep the fibers in a slightly dehumidified state of dry outside and moist inside, which is conducive to carding of the fibers by the carding element. If the relative humidity is too high during the combing process, the rolls, glue rollers and rollers are prone to sticking, and the cotton mesh is prone to holes. If the relative humidity is too low, static electricity will easily occur, resulting in broken edges and tops of the cotton web. It is more beneficial to production when the moisture regain of combed sliver is controlled at (65.0±2.0)%, which can ensure that the Uster evenness value of combed sliver is below 3.2%.
Table 2 Effect of relative humidity control on predraw quality
03 The influence of temperature and humidity on roughening
Under normal circumstances, the relative humidity of the roving should be controlled on the high side, so that the spun yarn can maintain a moisture-releasing state of internal moisture and external dryness. The internal moisture makes the cotton fiber soft and conductive, so the fiber will not be affected by electrostatic effects. Normal arrangement, good evenness. External dryness reduces friction and adhesion, which is beneficial to drafting and impurity removal.
Production practice shows that when the moisture regain of the roving is (6.8 ± 0.3)%, the phenomenon of cotton fibers wrapping around rubber rollers and rollers is greatly reduced, and the production status is optimal. When the relative humidity is too high (especially in high-temperature and high-humidity seasons), Xinjiang cotton with low sugar content is prone to winding around rubber rollers and rollers, making drafting difficult, affecting evenness, hard ends in rovings, and roving spindle shells. The astringency and friction increase, the resistance increases, the roving winding is difficult, the roving twist is uneven, the ends are increased, and the drawing process is prone to sliver sliver. At this time, the workshop temperature can be increased accordingly to reduce the relative humidity. If the relative humidity is too low, the drawn cotton sliver will easily generate static electricity, the cotton sliver will be fluffy, hairy, the cotton web will break, the fibers will scatter, and the fly will increase. The roving will be loose, twisting is difficult, there will be many ends breakage, and the cohesion between the roving fibers will be poor, which will affect the sliver quality. Uniformity and strength of roving, roving is prone to poor forming. The moisture regain of roving should generally be controlled at 6.5%~7.1%.
04 Effect of temperature and humidity on spinning yarn
The relative humidity in the spinning workshop is smaller than that in the roving workshop, so that the roving can maintain a dehumidifying state of internal moisture and external dryness in the spinning workshop. In this way, the fibers are soft and not easy to adhere, easy to process, have good conductivity, and have low friction, which is good for drafting. favorable. The control of temperature and humidity in the workshop is also related to the linear density of cotton fibers. Fine fibers are softer than coarse fibers, and have higher hollowness and are easier to absorb moisture. The production of fine fibers should have a lower humidity than the production of coarse fibers. If the relative humidity is too high, the friction between the yarn and the traveler and between the traveler and the steel ring will increase, which will easily cause the traveler to fly, fly particles to adhere to the surface of the roller and apron, and the rubber roller will become sticky and the rubber roller will wind. , the production of hard heads, etc. will be affected. Therefore, the relative humidity is required to be controlled at a low level, but it should not be too low. If the relative humidity is too low, it will easily cause the loss of cotton fibers and increase the number of flying flowers. It is easy to generate static electricity during the drafting process, winding the rubber rollers, increasing the hairiness of the yarn, and reducing the strength. Generally, the relative humidity of spun yarn should not exceed 60%, and the moisture regain is between 6.5% and 7.0%. The main indicators of combed 14.8 tex pure cotton yarn under different temperature and humidity conditions are shown in Table 3.
Table 3 Main indicators of C 14.8 tex under different temperature and humidity conditions
05 The influence of temperature and humidity on the winding process
Temperature is also very important for spun yarn production. High temperature will cause the moisture regain of roving to decrease and easily generate static electricity. The fiber cotton wax will melt, causing the strands of fiber to wrap around rubber rollers, wind around rollers, and cannot be drafted, etc., which is detrimental to production.
Due to the high speed of the automatic winding machine and the sensitive detection action, maintaining a certain relative humidity can increase the strength and moisture regain of the yarn, which is beneficial to clearing yarn defects, making the yarn surface smooth and reducing hairiness. If the relative humidity is too high, the package becomes heavy and the yarn absorbs moisture and elongates, making it difficult to remove impurities. The electric cleaner is prone to miscutting, and flying particles adhere to the surface of the machine parts and is prone to rust. If the relative humidity is too low, the yarn strength decreases and it is difficult to remove impurities. Miscellaneous, poor molding, increased hairiness, resulting in reduced quality. The relative humidity of the winding is generally controlled at 65%~75%, and the moisture regain is 7.0%~7.5%.
Air conditioning management must be scientific, institutionalized and standardized. Controlling the moisture regain of semi-finished products and finished products in the production process, and reducing the fluctuation of moisture regain in each process by focusing on processes, equipment, operations, etc. is the basis for stabilizing product quality and ensuring stable production operations.
</p
