In the early 1990s, a dyeing factory in Yuyao, Zhejiang first developed loose fiber dyeing technology to dye loose cotton and cotton cellulose fibers, which greatly reduced various pollution caused by yarn printing and dyeing. The gray and hazy cloth effect presented by split-color spinning is favored by fashion designers and is unmatched by tube yarn dyeing. However, after dyeing, the spinnability of loose fibers is reduced, each process is difficult to perform, production efficiency is reduced, and yarn quality indicators decline.
The spinnability of one-color spinning is reduced The main manifestations
1.1 Carding process
The problems of colored spinning yarn in the carding process are mainly caused by the two sides of the cotton mesh. The side falling net sags, or the cotton net absorbs the upper and lower pressure rollers, making it difficult to form slivers. Sometimes, although the cotton net can be formed into slivers, the cohesion of the slivers is poor, and the end is easy to break when driving at high speed, which can only reduce the production speed.
1.2 Roughing process
It is difficult to spin in the carding process. The varieties are generally difficult to spin in drawing. For example, the rubber roller absorbs flowers, cleans the velvet cover to accumulate flowers, winds the roller rubber roller, sometimes the coiling inclined tube does not hold the sliver, and it is blocked repeatedly, etc. When encountering these problems, measures such as reducing the vehicle speed, replacing rubber rollers and bell mouths often have no obvious effect.
1.3 Spinning process
The color-spun varieties with poor spinnability are Problems with winding rollers and rubber rollers often occur in the spinning process. Sometimes, after breakage, flying particles attach to adjacent spindles, causing large areas of breakage.
Analysis of the causes of poor spinnability and improvement measures
2.1 Spinnability of cotton and cellulose fibers after dyeing
2.1.1 Effect of dyeing on the fiber
The surface of the fiber after dyeing Waxes, oils, etc. are destroyed, the feel becomes hard, the strength decreases by 15-30%, the length decreases by 1-1.5mm, the short staple rate increases by 3-5%, and the neps increase by 20%, and as the dyeing depth increases , the fiber index drops more prominently, and ends breakage and neps are easily caused during spinning.
Therefore, it is very important to select the raw materials for dyeing: for loose cotton, we should pay attention to the horse value, that is, the thickness and maturity of the fiber. If it is too high or too low, the raw material index and spinning will be affected after dyeing. If the process causes adverse effects, the horse value should be controlled between 4.3-4.8, the maturity coefficient between 0.85-0.88, the length should be more than 28.5mm, and the impurity content should be within 1.5%.
Cellulose fibers are equal-length fibers. When choosing dyed fibers, the fineness should not be too fine. 1.5D is usually used. It is not recommended to use fine-denier fiber dyeing to avoid tangled fibers after dyeing and affecting the carding effect.
After dyeing, there is a large amount of floating color on the surface of the fiber, which needs to be removed by washing. Some darker colors (such as red, blue, etc.) floating dyes adhere to the fiber. It is highly resistant and difficult to clean from the fiber, which can easily lead to poor fastness of the finished product. Color fixing agents need to be added to improve it. In order to improve spinnability, softeners and a small proportion of antistatic agents need to be added.
2.1.2 Pretreatment of dyed fiber before spinning
(1) Opening. For a small proportion of dyed fibers in blended varieties, especially cellulose fibers, if the hardening is serious or even appears like “radish shreds”, a small opening machine needs to be used for pre-opening.
(2) Add additives. Static electricity generated by friction between fibers and machine parts is one of the main reasons affecting the spinnability of fibers. Especially in some color spinning mills in the north, the humidity in the workshops is generally low, making static electricity problems more likely to occur. For this purpose, a certain proportion of water and antistatic agent need to be added to the raw materials, sprayed evenly on the fiber layer, and left to sit for 12 hours before being put into production.
2.1.3 Measures to improve spinnability during spinning
(1) Workshop production environment. Reasonably adjust the temperature and humidity in the workshop. If necessary, you can “isolate” varieties with poor spinnability to partially adjust the temperature and humidity in this area so that they can be produced under a relatively closed and stable temperature and humidity condition.
(2) Improve equipment. Based on fiber characteristics, equipment such as rubber rollers, aprons, and bell mouths are optimized for each process to improve their adaptability to fibers.
(3) Fixed production line. If multiple varieties of color spinning are to be produced in a workshop, each variety must maintain a fixed production line to avoid frequent machine changes, which may cause fluctuations in production status.
2.2 Spinnability of non-dyed fibers and improvement measures
Polyester fiber has low moisture regain and high specific resistance. It is necessary to add active oil agent before spinning to form a thin film on the fiber surface to reduce fiber degradation. The surface friction coefficient reduces static electricity; it enhances the hygroscopicity of the fiber, reduces the specific resistance of the fiber surface, and increases the static electricity dissipation speed. However, the oil agent ratio must be accurately controlled. Too little oil agent will not achieve the expected improvement effect, and too much oil agent will cause fiber adhesion and machine parts entanglement. When purchasing raw materials, special attention should be paid to indicators such as oil content and curl recovery rate. The raw materials should be properly humidified before being put on the machine, and the relative humidity in the workshop should be increased.
2.2.2 Acrylic fiber
The main feature of acrylic fiber is its feel It is fluffy, has high rigidity, small compression elastic recovery rate, and is particularly sensitive to changes in temperature and humidity in the workshop. The strips are not tightly formed during the carding process, and the bell mouth is easily blocked when drawing, and the coiled inclined tube cannot be laid. It is necessary to take measures such as cleaning the sliver channel regularly, increasing the humidity in the workshop, and strengthening the moisturizing of semi-finished products. When outdoor conditions change, temperature and humidity must be adjusted promptly.Otherwise, phenomena such as sticking, wrapping, etc. may occur.
2.2.3 Modified acrylic fiber
In the fiber production process , modified acrylic fiber has added some modifying additives, which changes the structure and characteristics of the fiber itself, such as fire prevention, flame retardancy, etc. The strength of fire-proof acrylic fiber single fiber will decrease by 30-40%, and the fiber will be brittle and even break. There is powder falling off, which seriously affects the cleanliness and spinnability of each process. Therefore, it is necessary to optimize the pre-spinning process (especially blowing and carding) to achieve more loosening and less beating, gentle carding, and appropriately raise the height of the cotton feeding plate to reduce fiber damage.
Hemp fiber is bast fiber. The surface is rough, the degree of splitting is large, the fineness is coarse, the cohesion is poor, and the length is dispersed. It is difficult to produce when pure spinning. When blended with cotton, special additives need to be used for pretreatment to improve the cohesion of the fiber. During the production process, it is necessary to Local humidification is performed to increase the relative humidity in the production area to ensure spinnability.
Kapok fiber is a hollow fiber, hollow The fiber content is 80-90%, so the fiber is light, small in volume and mass, and easy to float. It needs to be blended with cotton or other fibers during spinning to ensure smooth production. The production area must be properly humidified to prevent the fiber from floating.
According to the characteristics of different raw materials, color spinning Different measures must be taken to deal with the problem of poor spinnability. </p