A cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers

Abstract

The application relates to a cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers, which comprises the following steps: adopting alkali liquor to dip and treat cotton yarn, the concentration of the alkali liquor is 120-400 g / L, then the cotton yarn is twisted and stretched in the alkali state, and the cotton yarn with increased length and reduced fineness is prepared; after the alkali liquor dipping treatment and the twisting and stretching, the average length of the cotton fibers in the cotton yarn is increased by 5.48-30.06%, the linear density is reduced by 5-42.12%, and the breaking strength of the cotton fibers is increased by 19.34-100.08%; the cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers is simple and feasible, the energy consumption is small, the length and the fineness of the cotton fibers can be effectively changed, and the modification of various performance indexes of the cotton fibers is obvious.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of textile dyeing and finishing, and relates to a cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers. BACKGROUND

[0002] Cotton is an important agricultural product related to the national economy and people's livelihood, and is also the main raw material of the textile industry. Cotton fibers with a length of more than 33 mm are called long-staple cotton. In the GB / T 19635-2005 Cotton Long-staple Cotton standard, the length of cotton fibers is indicated by length grade, and the length of cotton fibers is taken as the grade interval of 1 mm. Taking the length grade 38 mm as an example, the fiber length includes 38.0 mm to 38.9 mm. Long-staple cotton has the advantages of long length, high strength, and good length uniformity.

[0003] Traditional long-staple cotton mainly relies on hybrid breeding and seed selection. For example, in the southern region of Xinjiang, China, due to the suitable climate, long-staple cotton varieties were introduced from Egypt and after screening and optimization, excellent varieties such as Xinhai 25 and Xinhai 26 were cultivated. However, the seed selection and cultivation period is long and requires high-quality planting sites. Therefore, it is of great significance to seek a simple, low-cost method to obtain long-staple fibers.

[0004] The existing technology mainly focuses on the thinning and stretching of wool fibers, and the stretching modification of yak fibers also solves the problems of coarse, hard, and poor cohesion of original yak fibers. Taking the wool thinning and stretching product "Optimfine" as an example, the diameter of the original wool fiber can be reduced by 3 µm to 4 µm, the linear density is reduced by 1.4 dtex, and the specific strength is increased by 3 cN / tex. Wool fiber thinning and stretching directly act on wool fibers, and the stretching mechanism is the breaking and rearrangement of disulfide bonds and hydrogen bonds inside the fiber. The main auxiliaries used are reducing agents (sodium bisulfite) and setting agents. Cotton fibers are shorter than wool fibers, and it is difficult to directly stretch cotton fibers. When the yarn is directly stretched, the fibers in the yarn are prone to slip, and the effect of lengthening the fibers cannot be achieved. Therefore, this method of thinning and stretching wool fibers is not suitable for cotton fibers.

[0005] Document 1 (Dyeing and Finishing Process and Principle (Volume I) [M]. Beijing: China Textile Publishing House, 2009) records that in the yarn tension mercerization process, the original yarn length is stretched by 3%, 6%, and 9%, and after alkali immersion mercerization, the yarn strength can be increased by 20%.

[0006] Document 2 (Effects of tension on the swelling of cotton fibers [J]. Textile Research Journal, 1952, 22: 21-25) describes that, compared with the length of the cotton fiber bundle before treatment, the length of the cotton fiber bundle after treatment is increased by 2.4%, 5.3%, and 6.5% respectively under the conditions of dry state (without immersing any solution), immersing only distilled water, and immersing 18% aqueous alkali solution, under the tension of 2.23 N / mg, 1h, without twisting.

[0007] However, the above treatment process is to directly stretch the cotton yarn or cotton fiber bundle in a dry or wet state without twisting, which can cause slippage or breakage between fibers, and the degree of improvement of fiber length and breaking strength is small.

[0008] Therefore, it is of great significance to study a cotton yarn processing method for effectively increasing the length of cotton fibers and reducing the fineness of cotton fibers to solve the above problems. SUMMARY

[0009] To solve the problems in the prior art, the application provides a cotton yarn processing method for increasing the length of cotton fibers and reducing the fineness of cotton fibers.

[0010] To achieve the above purpose, the application adopts the following scheme:

[0011] A cotton yarn processing method for increasing the length of cotton fibers and reducing the fineness of cotton fibers, first immersing the cotton yarn in alkali solution, then twisting and stretching the cotton yarn in an alkali state, and obtaining a cotton yarn with improved length and fineness of cotton fibers; after immersing in alkali, the cotton fibers swell, and the twisting and stretching are performed in the swollen state, so as to achieve the purpose of lengthening and thinning the fibers; after immersing in alkali, the fibers in the yarn are loose, and the twisting can make the internal fibers tightly hold together, and the fibers are not easy to slip or break. If the yarn is directly stretched without twisting, slippage or breakage between fibers can occur, and the elongation of the yarn is not caused by the elongation of the fibers, but by the slippage of the fibers. Therefore, the twisting and stretching are performed in the alkali state of the yarn, which can achieve the purpose of lengthening and thinning the cotton fibers;

[0012] The concentration of the lye is 120-400 g / L; the lye will chemically react with the cellulose macromolecules in the cotton fibers to generate sodium alcoholate (for example, the lye is NaOH), thereby destroying the hydrogen bonds between the cellulose macromolecular chains and swelling the fibers. When the concentration of the lye is low, as the NaOH solution penetrates into the fibers, the fibers cannot be severely swelled and the crystalline regions cannot be destroyed. When the concentration of the lye is too high, the degree of fiber destruction is intensified, which can cause the fiber strength to decrease and the fiber to be easily broken; in addition, when the concentration of the lye is too high, the viscosity of the lye is too large, the permeability of the lye to the fibers is poor, and the surface layer of the fibers can be swelled but the interior of the fibers is not swelled by the lye;

[0013] After the lye immersion treatment and the twisting and stretching, the average length of the cotton fibers in the cotton yarn is increased by 5.48-30.06%, and the linear density is decreased by 5-42.12%.

[0014] As a preferred technical solution,

[0015] The cotton yarn processing method as described above increases the length of the cotton fibers and decreases the fineness of the cotton fibers, after the lye immersion treatment and the twisting and stretching, the orientation degree of the cotton fibers in the cotton yarn is increased, the cohesion is increased, the fiber breakage caused by stress concentration is reduced, and the breaking strength of the cotton fibers is increased by 19.34-100.08%.

[0016] The cotton yarn processing method as described above increases the length of the cotton fibers and decreases the fineness of the cotton fibers, the immersion treatment time is 5-300 s; if the time is too short, the fibers cannot be sufficiently swelled; if the time is too long, the fibers will not continue to increase after being swelled to the maximum, thereby wasting time.

[0017] The cotton yarn processing method as described above increases the length of the cotton fibers and decreases the fineness of the cotton fibers, the temperature during the lye treatment is 0-100℃; when the temperature is higher than 100℃, the fiber swelling percentage is sharply reduced; when the temperature is lower than 0℃, the viscosity of the lye is too large, the penetration efficiency of the lye to the interior of the fibers is low, and the surface of the cotton fibers is easily mercerized, and the interior of the fibers cannot be sufficiently swelled.

[0018] The cotton yarn processing method as described above increases the length of the cotton fibers and decreases the fineness of the cotton fibers, the lye is a sodium hydroxide solution or a potassium hydroxide solution.

[0019] The cotton yarn processing method as described above increases the length of the cotton fibers and decreases the fineness of the cotton fibers, the twisting number is 4-20 turns / 12 cm; when the number is less than 4 turns / 12 cm, the swelled yarn cannot be tightly re-cohesive; when the number is greater than 12 turns / 12 cm, the yarn is too tightly cohesive, the interior fibers are difficult to clean, the lye is left on the fibers, and after the removal of the stretching tension, the cotton fibers are shrunk due to the lye, and the lengthening and thinning effect is reduced.

[0020] The cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers as described above, the cotton yarn is mercerized or unmercerized cotton yarn.

[0021] The cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers as described above, before the alkali immersion treatment, the linear density of the cotton yarn is 11-90 tex, the twist factor is 350-470, and the linear density of the cotton fibers in the cotton yarn is 1.6-2.2 dtex.

[0022] The cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers as described above, after the twist stretching of the cotton yarn, water washing and drying are sequentially performed.

[0023] The principle of the present application is:

[0024] It is recorded in documents 3 (Mechanics and hierarchical structure transformation mechanism of wool fibers. Textile Research Journal, 2020, 91 (5-6): 496-507) and 4 (Hydroxyl changing mechanism of cotton cellulose during alkaline treatment characterized by ATR-FTIR in combination with two-dimensional correlation spectroscopy. AATCC Journal of Research, 2020, 7 (5): 1-8) that in the refining and stretching process of wool, the disulfide bond, hydrogen bond and peptide chain in the wool fiber are split or restructured, and the macromolecular conformation is changed from α type to β type, so that the wool fiber with obvious refining and lengthening effect can be obtained, which is similar to the mechanism of hydrogen bond restructuring and macromolecular conformation recombination in the alkali mercerization of cotton fibers.

[0025] Cotton fibers are difficult to be directly stretched due to the shorter single fiber length than wool fibers. When the yarn is directly stretched, the fibers in the yarn are prone to slip, and the effect of lengthening the fibers cannot be achieved.

[0026] In the traditional preparation method, the original hydrogen bond between the macromolecular chains of cotton fibers is weakened or disappears in the alkali treatment under pre-tension (pre-tension refers to applying a certain tension to the fibers before treating the fibers with alkali solution), more alkali metal ions and water molecules enter the fiber gap, the distance between the molecular chains increases, the fibers swell, and the molecular chains slip and rearrange under the action of external tension, the proportion of crystalline region decreases, and the proportion of amorphous region increases. The tension applied to both ends of the yarn is commonly used to achieve the alkali mercerization effect. In this process, the improvement of the performance of the fibers is mainly pursued, such as increasing the amorphous region of the fibers and improving the surface gloss of the fibers. In addition, in the traditional method, no twisting and stretching is applied, the yarn swells under the action of alkali (as shown in FIG. 1), the cohesion between the fibers is small, which causes the relative slipping of the internal fibers of the yarn, the tension acting on both ends of the fiber is limited, and the fiber thinning effect is not obvious. Figure 2

[0027] The present application adopts twisting and stretching, the hydrogen bonds between the cellulose macromolecules are destroyed under the action of alkali solution, after twisting the yarn, the cohesion between the fibers in the yarn is increased, which greatly reduces the possible relative slipping of the fibers under the action of external force. Twisting and stretching are carried out at the same time, the tension can effectively act on both ends of the fiber, the cellulose macromolecules in the internal fibers slip relatively, after washing, the alkali solution is washed away, the hydrogen bonds between the cellulose macromolecules are reformed, and the molecular conformation is fixed, so that the fiber is elongated and thinned. Compared with the traditional preparation method, in the method of the present application, after the fibers swell in the alkali treatment, twisting makes the cohesion between the fibers greater and less likely to slip, and the stretching force acting on the single fiber makes the degree of slipping of the fiber molecular chains greater, so the degree of elongation and thinning of the fiber is much greater than that of the traditional method. The present application focuses on the effect of making the cotton fibers longer and thinner, and improving the physical and mechanical properties of the fibers such as strength and softness, so as to achieve the similar effect of Egyptian cotton which is long and thin, soft and tough, and to improve the performance of the final fabric product.

[0028] In addition, the yarn needs to be immersed in alkali before twisting and stretching, the swelling of the yarn in this process will weaken the twist of the original yarn and the cohesion between the fibers, therefore, the cotton yarn needs to be immersed in alkali, twisted and stretched. Although the N-methyl morpholine-N-oxide solution system with a mass fraction less than 80% and the ethanol / water system can destroy the hydrogen bonds in the amorphous region during the swelling process, they cannot destroy the crystalline region. The carbon disulfide / NaOH / water system, the polyformaldehyde / dimethyl sulfoxide derivatization solvent system, and the lithium hydroxide / dimethyl acetamide non-derivatization solvent system can destroy the crystalline region during the dissolution process of cellulose, but they are dissolution processes for cotton fibers, and cannot realize twisting and stretching.

[0029] ​The structure of the cotton fiber is primary cell wall, S1 layer and S2 layer from outside to inside. When the alkali concentration is low, the S2 layer cellulose in the cotton fiber can only swell to a low degree, and cannot swell the fiber violently and destroy the crystalline region. When the alkali concentration is too high, the damage to the fiber is intensified, which can cause the fiber strength to decrease and be easy to break; in addition, when the alkali concentration is too high, the viscosity is too large, the permeability of the fiber is poor, and the fiber surface can be swelled, but the fiber inside is not swelled. Based on the above consideration, the alkali concentration is set to 120-400 g / L.

[0030] Advantages

[0031] (1) The cotton yarn processing method for increasing the length and reducing the fineness of cotton fiber can effectively change the fineness and length of the cotton fiber.

[0032] (2) The cotton yarn processing method for increasing the length and reducing the fineness of cotton fiber is simple and feasible, has low energy consumption, and can obviously improve the performance indicators of the cotton fiber. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The device flow chart used for the cotton yarn processing method for increasing the length and reducing the fineness of cotton fiber;

[0034] Figure 2 The optical microscope pictures of the yarn of the raw material in Comparative Example 1, the cotton yarn prepared in Comparative Example 1 and the cotton yarn with improved length and fineness prepared in Example 9; wherein (a) is the cotton fiber in the yarn of the raw material in Comparative Example 1, (b) is the cotton fiber in the cotton yarn prepared in Comparative Example 1, and (c) is the cotton fiber in the cotton yarn with improved length and fineness prepared in Example 9.

[0035] Figure 3 The morphology comparison chart of the cotton fiber in the yarn of the raw material in Comparative Example 1, the cotton fiber in the cotton yarn prepared in Comparative Example 1 and the cotton fiber in the cotton yarn with improved length and fineness prepared in Example 9; wherein (a) is the cotton fiber in the yarn of the raw material in Comparative Example 1, (b) is the cotton fiber in the cotton yarn prepared in Comparative Example 1, and (c) is the cotton fiber in the cotton yarn with improved length and fineness prepared in Example 9. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope of the claims attached to the present application.

[0037] As Figure 1As shown, it is a device flow chart used in a cotton yarn processing method for increasing the length of cotton fibers and reducing the fineness of cotton fibers, the cotton yarn is wound on a large drum with threads, the immersion time of the yarn in the immersion tank is controlled by changing the size of the drum, the thread pitch and adjusting the rotation speed of the drum. After the alkali immersion is completed, the yarn enters the twisting device, passes through the rotatable base support, and the base rotates one turn, and the yarn is twisted. The yarn is transferred to the roller stretching machine through the two pairs of guide rollers in the twisting device. The roller stretching machine has seven groups of multi-zone roller devices, each group of rollers is composed of three rollers. The diameters of the rollers in the roller group are different, the upper roller has a diameter of 60 mm and is covered with butadiene rubber to prevent fiber damage, and the lower roller has grooves. The larger roller in the lower roller has a diameter of 40 mm and is responsible for driving, and the smaller roller has a diameter of 20 mm and provides auxiliary action. The diameters of the three rollers are different, and when they rotate at the same angular velocity, the yarn around the surface of the roller will rotate at different linear velocities to achieve the stretching effect. After washing in the immersion tank and drying in the oven, the purpose of fixing the molecular chain conformation of the fiber is achieved, and the purpose of increasing the length of the cotton fiber and reducing the fineness of the cotton fiber is finally achieved.

[0038] The test methods involved in the following examples and comparative examples of the present application are as follows:

[0039] First, the cotton yarn is untwisted into fibers on the yarn twist machine, and then tested after being treated in an environment with a temperature of 20℃ and a relative humidity of 60% for 24h:

[0040] The breaking strength, breaking strength, breaking work, and breaking elongation of the cotton fiber are measured using an XQ-1 electronic single fiber strength tester in accordance with GB / T 14338-2022 Chemical fibers Test method for crimping performance of staple fibers. First, the fiber sample is pre-conditioned at a temperature of 20℃ and a relative humidity of 25% for 30min, then conditioned at a temperature of 20℃ and a relative humidity of 65% for 2h, and then tested for breaking strength, breaking strength, breaking work, and breaking elongation. The stretching program uses a rate of 10mm / min, the initial clamping distance is 10mm, and after stretching, the clamping distance automatically returns to the initial clamping distance. Each group of samples is measured 30 times to calculate the average value.

[0041] Cotton fiber linear density: according to GB / T 6100-2007 Cotton Fiber Linear Density Test Method Middle Section Weighing Method, the sample cotton fiber is conditioned at a temperature of 20°C and a relative humidity of 65% for 2 hours. The experimental conditions are a temperature of 20°C and a relative humidity of 65%. Prepare 10 mg of sample, tease and comb the sample, and remove the free fibers and short fibers less than 20 mm after combing with a dense comb tool. Separate the upper and lower clamps of the interrupter cutter, then place the combed cotton fiber in the middle of the upper and lower clamps of the cutter and perpendicular to the cutter. The neat end of the fine cotton fiber bundle is exposed 5 mm outside the clamp; the neat end of the long cotton fiber bundle is exposed 7 mm outside the clamp. When the cotton fiber bundle is placed on the lower clamp, hold the two ends of the cotton bundle with both hands, stretch the fibers straight, and then close the clamp to cut all the fibers. Use a precision torsion balance to weigh the middle section of the cotton fiber bundle to 0.01 mg. Use a black lint cloth board and tweezers to count the number of fibers in the cotton fiber bundle. The linear density calculation formula is:

[0042] ;

[0043] In the formula, p L Linear density, unit: millitex (mtex); m1 - middle section weight of the fiber bundle, unit: milligrams (mg); L - cut fiber length (L = 10 mm); n - fiber number, unit: root.

[0044] Cotton fiber length (mass average length): using the roller analyzer method, specifically: after the fiber sample is conditioned at a temperature of 20°C and a relative humidity of 65%, the cover of the roller analyzer is lifted, the handle is shaken to make the scale on the turbine coincide with the pointer, and the cotton bundle on the restrictor board is clamped with a No. 1 clamp and moved to the analyzer groove roller. When moving, the stopper under the No. 1 clamp should be tightly attached to the slide plate, and a horizontal wooden pad is used to support the No. 1 clamp so that the cotton bundle reaches the horizontal. The cover with the pressure roller is placed down, the No. 1 clamp is removed, the neat end of the fiber should be flush with the inner edge of the slide plate, and the spring is tightened. The two ends of the fiber not held are clamped with a No. 2 clamp twice, and the third time the free fibers exposed from the neat end are clamped and placed on the board to be twisted into a strip or a ring. In the future, every 1 week of handle rotation (if grouped according to 2 mm group spacing, then 2 weeks), the fibers separated from the grip are clamped out with the above method and collected on the board. Test times: each test cotton strip is tested 2 times. The difference between the results of 2 tests should meet the precision requirements.

[0045] ;

[0046] In the formula: L m Mass average length, unit: millimeters (mm); L j Group median length of the jth group of fibers; m j Weight of the jth group of fibers.

[0047] Example 1

[0048] A cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers, the specific steps are as follows:

[0049] (1) Preparation of raw materials:

[0050] The cotton yarn is a cotton yarn that has not been mercerized; the linear density of the cotton yarn is 11 tex, and the twist factor is 350; the linear density of the cotton fibers in the cotton yarn is 1.6 dtex, the breaking strength is 3.63 cN, the breaking strength is 22.69 cN / tex, the average length is 28.4 mm, the breaking elongation is 4.8%, and the breaking work is 0.86 cN·mm;

[0051] The alkali solution is a sodium hydroxide solution with a concentration of 140 g / L, and the solvent is water;

[0052] (2) The cotton yarn is immersed in the alkali solution at a temperature of 0℃ for 5s, then twisted and stretched in the presence of alkali, and finally washed and dried in sequence to obtain a cotton yarn with improved length and fineness of cotton fibers; wherein the twisting turns are 4 turns / 12 cm.

[0053] The average length of the cotton fibers in the cotton yarn with improved length and fineness of cotton fibers is increased by 10.56%, the linear density is reduced by 7.5%, the breaking strength is increased by 46.76%, the breaking strength is 4.93 cN, the breaking elongation is 3.58%, and the breaking work is 1.07 cN·mm.

[0054] Example 2

[0055] A cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers, the specific steps are as follows:

[0056] (1) Preparation of raw materials:

[0057] The cotton yarn is a cotton yarn that has not been mercerized; the linear density of the cotton yarn is 90 tex, and the twist factor is 470; the linear density of the cotton fibers in the cotton yarn is 2.2 dtex, the breaking strength is 4.21 cN, the breaking strength is 19.1 cN / tex, the average length is 30.4 mm, the breaking elongation is 5.62%, and the breaking work is 1.09 cN·mm;

[0058] The alkali solution is a sodium hydroxide solution with a concentration of 400 g / L, and the solvent is water;

[0059] (2) The cotton yarn is immersed in the lye with a temperature of 15 DEG C for 300 s, then twisted and stretched in the state of containing the lye, and finally washed with water and dried in sequence to obtain the cotton yarn with improved length and fineness of cotton fibers; wherein the twisting number is 20 turns / 12 cm.

[0060] The average length of the cotton fibers in the cotton yarn with improved length and fineness of cotton fibers is increased by 6.91%, the linear density is decreased by 5.9%, the breaking strength is increased by 33.51%, the breaking force is 5.28 cN, the breaking elongation is 4.7%, and the breaking work is 1.77 cN·mm.

[0061] Example 3

[0062] A cotton yarn processing method for increasing the length and decreasing the fineness of cotton fibers, and the specific steps are as follows:

[0063] (1) Preparation of raw materials:

[0064] The cotton yarn is mercerized cotton yarn; the linear density of the cotton yarn is 11 tex, and the twisting coefficient is 470; the linear density of the cotton fibers in the cotton yarn is 1.6 dtex, the breaking force is 4.02 cN, the breaking strength is 25.13 cN / tex, the average length is 28.9 mm, the breaking elongation is 5.2%, and the breaking work is 0.94 cN·mm;

[0065] The lye is a sodium hydroxide solution with a concentration of 190 g / L, and the solvent is water;

[0066] (2) The cotton yarn is immersed in the lye with a temperature of 30 DEG C for 240 s, then twisted and stretched in the state of containing the lye, and finally washed with water and dried in sequence to obtain the cotton yarn with improved length and fineness of cotton fibers; wherein the twisting number is 4 turns / 12 cm.

[0067] The average length of the cotton fibers in the cotton yarn with improved length and fineness of cotton fibers is increased by 8.3%, the linear density is decreased by 6.25%, the breaking strength is increased by 20.69%, the breaking force is 4.55 cN, the breaking elongation is 3.23%, and the breaking work is 1.31 cN·mm.

[0068] Example 4

[0069] A cotton yarn processing method for increasing the length and decreasing the fineness of cotton fibers, and the specific steps are as follows:

[0070] (1) Preparation of raw materials:

[0071] The cotton yarn is mercerized cotton yarn; the linear density of the cotton yarn is 90 tex, and the twist factor is 350; the linear density of the cotton fiber in the cotton yarn is 2.2 dtex, the breaking strength is 3.89 cN, the breaking strength is 17.68 cN / tex, the average length is 30.7 mm, the breaking elongation is 4.92%, and the breaking work is 0.97 cN·mm;

[0072] The alkali solution is a sodium hydroxide solution with a concentration of 330 g / L, and the solvent is water;

[0073] (2) The cotton yarn is immersed in an alkali solution at a temperature of 45°C for 20 s, then twisted and stretched in the presence of alkali, and finally washed with water and dried in sequence to obtain a cotton yarn with improved cotton fiber length and fineness; wherein the twisting number is 16 turns / 12 cm.

[0074] In the cotton yarn with improved cotton fiber length and fineness, the average length of the cotton fiber increases by 6.84%, the linear density decreases by 5.9%, the breaking strength increases by 19.34%, the breaking strength is 4.37 cN, the breaking elongation is 3.58%, and the breaking work is 1.07 cN·mm.

[0075] Example 5

[0076] A cotton yarn processing method for increasing the length of cotton fibers and reducing the fineness of cotton fibers, the specific steps are as follows:

[0077] (1) Preparation of raw materials:

[0078] The cotton yarn is not mercerized cotton yarn; the linear density of the cotton yarn is 11 tex, and the twist factor is 440; the linear density of the cotton fiber in the cotton yarn is 2 dtex, the breaking strength is 3.96 cN, the breaking strength is 19.8 cN / tex, the average length is 29.5 mm, the breaking elongation is 5.48%, and the breaking work is 0.99 cN·mm;

[0079] The alkali solution is a sodium hydroxide solution with a concentration of 140 g / L, and the solvent is water;

[0080] (2) The cotton yarn is immersed in an alkali solution at a temperature of 60°C for 5 s, then twisted and stretched in the presence of alkali, and finally washed with water and dried in sequence to obtain a cotton yarn with improved cotton fiber length and fineness; wherein the twisting number is 8 turns / 12 cm.

[0081] In the cotton yarn with improved cotton fiber length and fineness, the average length of the cotton fiber increases by 8.14%, the linear density decreases by 6.5%, the breaking strength increases by 46.11%, the breaking strength is 5.41 cN, the breaking elongation is 3.7%, and the breaking work is 1.25 cN·mm.

[0082] Example 6

[0083] A cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers, the specific steps are as follows:

[0084] (1) Preparation of raw materials:

[0085] The cotton yarn is a cotton yarn without mercerization treatment; the linear density of the cotton yarn is 90 tex, and the twist factor is 380; the linear density of the cotton fibers in the cotton yarn is 1.8 dtex, the breaking strength is 3.78 cN, the breaking strength is 21 cN / tex, the average length is 29.8 mm, the breaking elongation is 5%, and the breaking work is 0.89 cN·mm;

[0086] The alkali solution is a potassium hydroxide solution with a concentration of 400 g / L, and the solvent is water;

[0087] (2) The cotton yarn is immersed in the alkali solution at a temperature of 100°C for 150s, then twisted and stretched in the presence of alkali, and finally washed with water and dried in sequence to obtain a cotton yarn with improved length and fineness of cotton fibers; wherein the twisting number is 20 turns / 12 cm.

[0088] The average length of the cotton fibers in the obtained cotton yarn with improved length and fineness of cotton fibers is increased by 15.77%, the linear density is reduced by 19.44%, the breaking strength is increased by 69.05%, the breaking strength is 5.16 cN, the breaking elongation is 4.7%, and the breaking work is 1.21 cN·mm.

[0089] Example 7

[0090] A cotton yarn processing method for increasing the length and reducing the fineness of cotton fibers, the specific steps are as follows:

[0091] (1) Preparation of raw materials:

[0092] The cotton yarn is a cotton yarn after mercerization treatment; the linear density of the cotton yarn is 18 tex, and the twist factor is 440; the linear density of the cotton fibers in the cotton yarn is 1.8 dtex, the breaking strength is 4.16 cN, the breaking strength is 23.1 cN / tex, the average length is 29.2 mm, the breaking elongation is 4.8%, and the breaking work is 0.86 cN·mm;

[0093] The alkali solution is a potassium hydroxide solution with a concentration of 140 g / L, and the solvent is water;

[0094] (2) The cotton yarn is immersed in the alkali solution at a temperature of 75°C for 120s, then twisted and stretched in the presence of alkali, and finally washed with water and dried in sequence to obtain a cotton yarn with improved length and fineness of cotton fibers; wherein the twisting number is 8 turns / 12 cm.

[0095] The average length of the cotton fibers in the cotton yarn with improved length and fineness of the cotton fibers is increased by 5.48%, the linear density is reduced by 5%, the breaking strength is increased by 34.48%, the breaking strength is 5.33 cN, the elongation at break is 2.7%, and the breaking work is 1.36 cN·mm.

[0096] Example 8

[0097] A cotton yarn processing method for increasing the length and reducing the fineness of the cotton fibers, and the specific steps are as follows:

[0098] (1) Preparation of raw materials:

[0099] The cotton yarn is a mercerized cotton yarn; the linear density of the cotton yarn is 32 tex, and the twist factor is 380; the linear density of the cotton fibers in the cotton yarn is 2 dtex, the breaking strength is 4.05 cN, the breaking strength is 20.25 cN / tex, the average length is 28.5 mm, the elongation at break is 3.9%, and the breaking work is 0.8 cN·mm;

[0100] The alkali solution is a potassium hydroxide solution with a concentration of 400 g / L, and the solvent is water;

[0101] (2) The cotton yarn is immersed in the alkali solution at a temperature of 60°C for 240 s, then twisted and stretched in the alkali state, and finally washed with water and dried in sequence to obtain a cotton yarn with improved length and fineness of the cotton fibers; wherein the twisting turns are 14 turns / 12 cm.

[0102] The average length of the cotton fibers in the cotton yarn with improved length and fineness of the cotton fibers is increased by 5.48%, the linear density is reduced by 5%, the breaking strength is increased by 34.48%, the breaking strength is 5.33 cN, the elongation at break is 2.7%, and the breaking work is 1.36 cN·mm.

[0103] Example 9

[0104] A cotton yarn processing method for increasing the length and reducing the fineness of the cotton fibers, and the specific steps are as follows:

[0105] (1) Preparation of raw materials:

[0106] The cotton yarn is a mercerized cotton yarn; the linear density of the cotton yarn is 32 tex, and the twist factor is 380; the linear density of the cotton fibers in the cotton yarn is 2 dtex, the breaking strength is 4.05 cN, the breaking strength is 20.25 cN / tex, the average length is 28.5 mm, the elongation at break is 3.9%, and the breaking work is 0.8 cN·mm;

[0107] The alkali solution is a potassium hydroxide solution with a concentration of 260 g / L, and the solvent is water.

[0108] (2) The cotton yarn is immersed in the alkali solution at 45℃ for 80s, then twisted and stretched in the presence of alkali, and finally washed with water and dried to obtain a cotton yarn with improved length and fineness of the cotton fibers; wherein the twisting number is 14 turns / 12 cm.

[0109] The average length of the cotton fibers in the cotton yarn with improved length and fineness of the cotton fibers is increased by 30.06%, the linear density is reduced by 40.12%, the breaking strength is increased by 100.08%, the breaking strength is 5.08 cN, the elongation at break is 3.2%, and the breaking work is 1.36 cN·mm.

[0110] Comparative Example 1

[0111] A cotton yarn processing method, which is basically the same as Example 9, except that the step of twisting and stretching the cotton yarn in step (2) is omitted.

[0112] The obtained cotton yarn is an alkali-shrunk yarn, and the cotton fibers in the alkali-shrunk yarn are alkali-shrunk cotton fibers. The average length of the alkali-shrunk cotton fibers is reduced by 11.03%, the linear density is increased by 17.2%, the breaking strength is increased by 3.5%, the breaking strength is 4.55 cN, the elongation at break is 9.3%, and the breaking work is 2.83 cN·mm.

[0113] Compared with Example 9, the cotton fibers after alkali shrinking in Comparative Example 1 swell, the average length of the fibers decreases, and the linear density increases. Without twisting and stretching, the fibers do not undergo orientation under tension, and the breaking strength and breaking strength decrease. The elongation at break of the fibers increases after alkali shrinking, and the breaking work also increases due to the significant increase in the elongation at break.

[0114] In Figure 2 , as shown in (a) and (b) of Figure 2 , the fiber holding degree of the alkali-shrunk yarn prepared in Comparative Example 1 is looser than that of the yarn in the raw material in Comparative Example 1, the yarn swells, and the gap between the internal fibers is larger than that of the original yarn; as shown in (c) of Figure 2 , the internal fiber holding degree of the yarn prepared in Example 9 is more compact than that of the original yarn, and there is almost no gap between the fibers. Therefore, twisting and stretching can effectively prevent fiber slippage.

[0115] In Figure 3 , as shown in (a) of Figure 3 , the cotton fibers in the yarn in the raw material in Comparative Example 1 have natural twist in the natural state, which is one of the characteristic morphologies of cotton fibers. As shown in (b) of Figure 3As shown in (b) of FIG. 1, after alkali mercerization, the natural twist of the cotton fibers in the cotton yarn prepared in Comparative Example 1 disappears completely due to swelling, the fiber surface wrinkles disappear, and the fibers become very smooth cylinders. As shown in (c) of FIG. 1, the cotton fibers in the cotton yarn prepared in Example 9 are thinner than those in the cotton yarn prepared in Comparative Example 1, and thus the thinning effect of the cotton yarn on the cotton fibers after immersion in alkali and twisting and stretching is more significant in terms of the morphological characteristics. Figure 3

[0116] Comparative Example 2

[0117] A cotton yarn processing method is basically the same as that in Example 9, except that the step of twisting the cotton yarn in step (2) is omitted, and the cotton yarn is directly stretched in an alkali state after immersion in the alkali solution.

[0118] The average length of the cotton fibers in the cotton yarn prepared in Example 10 is increased by 2.27%, the linear density is reduced by 2.72%, the breaking strength is increased by 31.35%, the breaking strength is 5.2 cN, the breaking elongation is 5.3%, and the breaking work is 1.87 cN·mm.

[0119] Compared with Example 9, the breaking strength, breaking strength, length increase, and linear density reduction of the fibers obtained by twisting and stretching in Comparative Example 2 are lower than those in Example 9, because without twisting and stretching, the fibers can be effectively stretched under tension similar to tension mercerization, but due to swelling of the yarn after immersion in alkali, the twist decreases, and fiber slippage easily occurs, so the fibers cannot be effectively stretched, the internal fiber tension orientation is limited, and the length increase and linear density reduction are lower than those in Example 9. The limited tension orientation of the internal fibers leads to lower breaking strength and breaking strength than those in Example 9.

[0120] Example 10

[0121] A cotton yarn processing method for increasing the length of cotton fibers and reducing the fineness of cotton fibers includes the following specific steps:

[0122] (1) Preparation of raw materials:

[0123] The cotton yarn is a mercerized cotton yarn; the linear density of the cotton yarn is 59 tex, and the twist factor is 440; the linear density of the cotton fibers in the cotton yarn is 2.2 dtex, the breaking strength is 4.15 cN, the breaking strength is 18.86 cN / tex, the average length is 28.7 mm, the breaking elongation is 3.1%, and the breaking work is 0.51 cN·mm;

[0124] The alkali solution is a potassium hydroxide solution with a concentration of 260 g / L, and the solvent is water;

[0125] ​(2) The cotton yarn is immersed in the lye with a temperature of 75 DEG C for 240 s, then twisted and stretched in the alkaline state, and finally washed and dried in sequence to obtain the cotton yarn with improved length and fineness of the cotton fibers; wherein the twisting number is 16 turns / 12 cm.

[0126] In the cotton yarn with improved length and fineness of the cotton fibers, the average length of the cotton fibers is increased by 9.76%, the linear density is decreased by 11.36%, the breaking strength is increased by 42.1%, the breaking strength is 5.22 cN, the breaking elongation is 4.5%, and the breaking work is 1.34 cN·mm.

Claims

1. A method for processing cotton yarn by increasing the length of cotton fibers and reducing the fineness of cotton fibers, characterized in that: First, the cotton yarn is impregnated with an alkaline solution, and then the cotton yarn is twisted and stretched in an alkaline state to obtain cotton yarn with improved cotton fiber length and fineness. The concentration of the alkaline solution is 120–400 g / L; After alkaline impregnation and twisting and stretching, the average length of cotton fibers in cotton yarn increases by 5.48–30.06%, the linear density decreases by 5–42.12%, and the breaking strength increases by 19.34–100.08%.

2. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, The immersion treatment time is 5 to 300 seconds.

3. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, The temperature during alkaline treatment is 0–100℃.

4. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, The alkaline solution is either sodium hydroxide solution or potassium hydroxide solution.

5. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, The number of twists is 4 to 20 per 12 cm.

6. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, Cotton yarn can be mercerized or unmercerized.

7. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, Before alkaline impregnation, the linear density of the cotton yarn is 11-90 tex, the twist coefficient is 350-470, and the linear density of the cotton fibers in the cotton yarn is 1.6-2.2 dtex.

8. The cotton yarn processing method for increasing cotton fiber length and reducing cotton fiber fineness according to claim 1, characterized in that, After twisting and stretching, the cotton yarn is then washed and dried in sequence.

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