Method for manufacturing ring-dyed yarn from waste pure cotton fabric and yarn and fabric

Abstract

The application discloses a method for manufacturing ring-dyed-like yarn from waste pure cotton fabric, and yarn and fabric, and belongs to the field of textiles. The method comprises the following steps: crushing white waste pure cotton fabric into loose fibers; dyeing the loose fibers into first loose fibers, second loose fibers and third loose fibers with gradually deepened colors; additionally dyeing long-fiber cotton into colored cotton fibers with a color deeper than that of the third loose fibers; and spinning to obtain ring-dyed-like yarn. During the drawing process, slivers formed by the colored cotton fibers, the first loose fibers, the second loose fibers and the third loose fibers are arranged in the same plane in the order of deep to shallow and shallow to deep according to the colors. Finally, yarn with gradually shallower colors from the outside to the inside can be obtained, which has a ring-dyed-like effect, is beneficial to making the unique aging effect of denim fabric, and enables the long-fiber cotton to be on the outermost side during the drawing process, which is beneficial to improving the strength of the yarn, making up for the insufficient strength of the loose fibers and making the denim fabric have a relatively rough effect.

Description

Technical Field

[0001] This invention relates to a method for producing ring-dyed yarn from waste pure cotton fabric, as well as the yarn and fabric, belonging to the textile field. Background Technology

[0002] Traditional denim fabric is made by interlacing pure cotton warp yarns dyed with indigo dye with off-white weft yarns. After finishing and washing processes, denim clothing can be given a unique "distressed" retro style effect. It is through the washing process that denim clothing is given additional value, which makes it stand on the stage of fashion clothing and become an irreplaceable element in the clothing market.

[0003] Due to the inherent properties of indigo dye, dyeing yarn primarily involves immersion and binding to allow the dye to penetrate. Some dye bonds with the fiber via hydrogen bonds, while the majority adheres to the fiber surface. Traditional indigo dyeing processes typically use 6 to 8 vats for immersion and dyeing, each vat generally holding 1000-1500L of solution containing indigo dye, sodium hydrosulfite, sodium hydroxide, and other chemicals. For dark denim fabrics, the yarn passes through even more vats during dyeing, resulting in a longer dyeing time. Because most of the indigo dye adheres to the fiber surface, with only a small portion bonding via hydrogen bonds, the yarn undergoes multiple pressure rollers to press it, causing the center of the yarn cross-section to be white, gradually darkening outwards – a process known in the industry as ring dyeing. After fading, this creates a unique distressed effect.

[0004] With economic development and social progress, the problem of waste textile disposal has become increasingly serious. Statistics show that my country recycled a total of 4.3 million tons of waste textiles in 2018, with a total recycling value of approximately 1.7 billion yuan. Textile fiber consumption is approximately 35 million tons annually, while generating about 20 million tons of waste textiles each year. People discard these textiles after wearing them for a certain period, and over time, the amount of waste textiles increases significantly. However, the annual recycling rate is less than 20%, with the remaining waste textiles generally disposed of through centralized incineration or landfill. Therefore, the country has been advocating for resource recycling.

[0005] According to incomplete statistics, global denim fabric production is around 5-6 billion meters, averaging 6-7 pieces per person. If waste textiles can be recycled into denim fabric, it would increase the avenues for recycling waste textiles. Denim fabric is made by first dyeing the yarn, then weaving, and finally washing and aging it. Therefore, waste pure cotton fabric cannot be directly dyed to make denim. How to transform waste textiles into yarn with ring-dyeing properties is a technical problem that still needs to be solved in this field. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a method for making ring-dyed yarn from waste pure cotton fabric, and provides yarn obtained by the method and fabric made from the yarn.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] In a first aspect, this application provides a method for producing ring-dyed yarn from waste pure cotton fabric, comprising the following steps:

[0009] The white, waste pure cotton fabric was broken into loose fibers.

[0010] The loose fibers are dyed into first loose fibers, second loose fibers and third loose fibers with progressively darker colors. Long-staple cotton is then dyed into colored cotton fibers that are darker than the third loose fiber.

[0011] Spinning to obtain the ring-dyed yarn; wherein, in the drawing process, the slivers formed by the colored cotton fibers, the first loose fibers, the second loose fibers and the third loose fibers are arranged on the same plane in order of color from dark to light and then from light to dark for drawing.

[0012] The method for producing ring-dyed yarn from waste pure cotton fabric provided in this application takes into account that denim fabric is dyed before weaving rather than woven before dyeing. The white waste pure cotton fabric is broken into loose fibers, and the loose fibers are dyed in advance before being re-spun. This helps to reduce the amount of dye used, make the loose fibers dyed evenly, and make it easy to dye multiple groups of loose fibers with different color depths. When drawing, the various fibers are arranged in the order of dark to light and then light to dark, and finally a yarn with the color gradually lightening from the outside to the inside can be produced, which has a ring-dyed effect. This is conducive to creating the unique distressed effect of denim fabric. In addition, the long-staple cotton is placed on the outermost side when drawing, which helps to improve the yarn strength and make up for the lack of strength of loose fibers, which is conducive to creating a rougher effect of denim fabric.

[0013] Further, the step of dyeing the loose fibers into first loose fibers, second loose fibers, and third loose fibers with progressively darker colors, and then dyeing long-staple cotton into colored cotton fibers that are darker than the third loose fiber, includes:

[0014] The long-staple cotton and the loose fibers are dyed using the same process. The dyed long-staple cotton is then washed with water and dried to obtain the colored cotton fibers. The dyed loose fibers are divided into three groups and bleached with washing and bleaching solutions of different concentrations. After drying, the first loose fiber, the second loose fiber, and the third loose fiber are obtained.

[0015] Dyeing all fibers the same color first and then fading them using different processing conditions, instead of dyeing multiple groups of fibers directly with dye solutions of different concentrations, helps the fiber color to be more durable, reduces color differences that occur after garment making and washing, and the pre-fading process helps to create the distressed effect of denim fabric. It can save the washing and distressing process after garment making, and it is easier to fade unwoven fibers than to fade the finished garment, which helps to save the amount of fading solution used and shorten the time required for fading.

[0016] Furthermore, the loose fibers treated with 2 g / L hydrogen peroxide as a washing and fading solution become the third loose fiber after drying; the loose fibers treated with 4 g / L hydrogen peroxide as a washing and fading solution become the second loose fiber after drying; and the loose fibers treated with 6 g / L hydrogen peroxide as a washing and fading solution become the first loose fiber after drying.

[0017] In a more preferred embodiment, the washing solution contains 1 g / L of sodium hydroxide, which helps to enhance the washing effect of the washing solution.

[0018] Furthermore, the time for the loose fiber that becomes the third loose fiber to be treated with the washing and fading solution during the fading process is 10 minutes, the time for the loose fiber that becomes the second loose fiber to be treated with the washing and fading solution during the fading process is 15 minutes, and the time for the loose fiber that becomes the first loose fiber to be treated with the washing and fading solution during the fading process is 20 minutes.

[0019] Furthermore, the drawing process consists of two combined steps: the first step involves combining slivers combed from the same type of fiber into one second sliver in every 6 or 8 slivers; the second step involves combining 8 second slivers into one third sliver in a transverse arrangement of colored cotton fiber-third loose fiber-second loose fiber-first loose fiber-first loose fiber-second loose fiber-third loose fiber-colored cotton fiber; the spinning steps after the drawing process include a roving process and a spinning process on the third sliver to obtain the ring-dyed yarn.

[0020] In the first pass, fibers of the same color depth are allowed to merge together on their own. In the second pass, they are arranged and merged together according to their color depth. This helps to make the final yarn more similar to the effect of conventional ring-dyed yarn.

[0021] Furthermore, the spinning step includes an opening process and a carding process before the drawing process. The requirements for the opening process of the first loose fiber, the second loose fiber, and the third loose fiber are as follows: the distance of the beater of the cotton grabber descends by 2 mm each time, the rotation speed is set to 900 r / min, the speed of the rotary carriage is set to 2.3 r / min, the blade extends 3 mm beyond the rib, the blade speed is set to 760 r / min, the fan speed is set to 920 r / min, the interval between the beater and the balance roller is 9 mm, the speed of the cotton lap roller is set to 11 r / min, and the dry weight of the cotton lap is 345 g / m.

[0022] Conventional process requirements can be used when opening colored cotton fibers, while the above-mentioned specific process requirements can effectively reduce the damage to loose fibers during machine processing when opening loose fibers.

[0023] Furthermore, the requirements for the carding process of the first loose fiber, the second loose fiber, and the third loose fiber are as follows: the distance between the cylinder and the licker-in roller is set to 11 filaments, the distance between the cylinder and the doffer is set to 5 filaments, the cylinder speed is set to 278 r / min, the licker-in roller speed is set to 580 r / min, the doffer speed is set to 15.2 r / min, the flats speed is set to 181 mm / min, and the carding dry weight is 18.5 g / 5 m.

[0024] Similarly, combing loose fibers using the specific process requirements mentioned above helps protect loose fibers with lower strength.

[0025] Secondly, this application provides a yarn made by the method described in the first aspect, which has an effect similar to ring-dyed yarn.

[0026] Thirdly, this application provides a fabric that uses the yarn described in the second aspect as the warp yarn, which can achieve the effect of denim fabric using recycled yarn, and the yarn has high strength.

[0027] The beneficial effects of this invention are: This invention directly dyes the loose fibers obtained from the shredded recycled clothing, which helps to reduce the amount of dye used, makes the loose fibers dyed evenly, and makes it easy to dye multiple groups of loose fibers with different color depths. When spinning, a specific drawing process is used to finally produce yarns with colors that gradually lighten from the outside to the inside, which has a similar effect to ring dyeing. This is conducive to creating the unique distressed effect of denim fabric. In addition, when drawing, the long-staple cotton is used as the outermost layer, which helps to improve the yarn strength, make up for the lack of strength of loose fibers, and help to create a rougher effect for denim fabric.

[0028] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description. Detailed Implementation

[0029] In the process of textile recycling, physical and chemical methods are usually used to process and reuse waste textiles. When making denim fabric from waste textiles, it is important to note that denim is dyed before weaving, not the other way around. Therefore, the recycled textiles need to be shredded before spinning. However, the resulting yarn has lower strength and can generally only be used as weft yarn. Furthermore, the fabric made from this yarn still sometimes fails to meet the weft strength standards, which limits the development of recycled cotton fibers.

[0030] This application provides a method for producing ring-dyed yarn from waste pure cotton fabric, including the following steps:

[0031] S1: The white waste pure cotton fabric is broken into loose fibers. Preferably, the length of the loose fibers is distributed between 10mm and 30mm.

[0032] S2: Dye loose fibers into first loose fibers, second loose fibers, and third loose fibers with progressively darker colors, and then dye long-staple cotton into colored cotton fibers that are darker than the third loose fiber.

[0033] S3: Spinning to obtain ring-dyed yarn. Those skilled in the art will understand that spinning sequentially includes opening, carding, drawing, roving, and spinning processes. In the drawing process of this application embodiment, slivers formed from colored cotton fibers, first loose fibers, second loose fibers, and third loose fibers are arranged on the same plane in order of color from dark to light and then from light to dark for drawing.

[0034] In this embodiment, after step S1, the loose fibers are dyed in advance before they are re-spun. This helps to reduce the amount of dye used, makes the loose fibers dyed evenly, and makes it easy to dye multiple groups of loose fibers with different color depths. With the help of a specific step S3, yarns with colors gradually lightening from the outside to the inside can be obtained, which has a similar effect to ring dyeing. This is conducive to creating the unique distressed effect of denim fabric. Furthermore, when drawing the yarn, the long-staple cotton is placed on the outermost side, which helps to improve the yarn strength and make up for the lack of strength of loose fibers, thus helping to create a rougher effect for denim fabric.

[0035] Preferably, step S2 includes: dyeing long-staple cotton and loose fibers using the same process, then washing the dyed long-staple cotton with water and drying it to obtain colored cotton fibers; and dividing the dyed loose fibers into three groups and bleaching them with different concentrations of washing and bleaching solutions, and drying them to obtain the first loose fiber, the second loose fiber, and the third loose fiber. Specifically, the dyeing process can be as follows: indigo dye, sodium hydrosulfite, sodium hydroxide, and a dispersant are added to the dye bath. The indigo dye content is 2.2 g / L - 2.6 g / L, the sodium hydrosulfite content is 1.1 g / L - 1.4 g / L, the sodium hydroxide content is 2.1 g / L - 2.4 g / L, and the dispersant content is 0.5 g / L - 2 g / L.

[0036] This application embodiment does not directly dye multiple groups of fibers with dye solutions of different concentrations. Instead, it dyes all fibers the same color first and then washes them with different process conditions. This is beneficial for the fiber color to be more durable, reduces color difference after subsequent garment making and washing, and the pre-washing and fading is conducive to creating the distressed effect of denim fabric. It can save the washing and distressing step after garment making. It is also easier to fade uninterwoven fibers than to fade finished garments, which helps to save the amount of washing and fading solution used and shorten the washing and fading time.

[0037] Specifically, the dyed long-staple cotton is washed with clean water for 10-20 minutes and dried to obtain colored cotton fibers. The loose fibers after heat dissipation are divided into three groups. The first group is treated with a washing solution containing 6 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 20 minutes and dried to obtain the first loose fiber. The second group is treated with a washing solution containing 4 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 15 minutes and dried to obtain the second loose fiber. The third group is treated with a washing solution containing 2 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 10 minutes and dried to obtain the third loose fiber. Compared with oxygen bleaching, chlorine bleaching, and enzyme bleaching for denim garments, the pre-washing method in this application uses fewer chemicals and consumes less water and electricity, which is conducive to sustainable development.

[0038] The specific steps of step S3 are as follows:

[0039] S31: During opening, colored cotton fibers are processed using conventional methods. For loose fibers, the batter of the cotton grabber descends 2mm each time, the rotation speed is set to 900r / min, the rotary carriage speed is set to 2.3r / min, the blade extends 3mm beyond the rib, the blade speed is set to 760r / min, the fan speed is set to 920r / min, the interval between the batter and the balance roller is 9mm, the cotton roll roller speed is set to 11r / min, and the dry weight of the cotton roll is 345g / m.

[0040] S32: During carding, colored cotton fibers are treated using conventional processes. For loose fibers, the cylinder-licker-in distance is set to 11 filaments, the cylinder-doffer distance is set to 5 filaments, the cylinder speed is set to 278 r / min, the licker-in speed is set to 580 r / min, the doffer speed is set to 15.2 r / min, the flats speed is set to 181 mm / min, and the carding dry weight is 18.5 g / 5 m.

[0041] S33: The drawing process consists of two steps. The first step is to combine slivers made from the same type of fiber into one second sliver in every 6 or 8 slivers. The second step is to combine 8 second slivers into one third sliver in the transverse arrangement of colored cotton fiber - third loose fiber - second loose fiber - first loose fiber - first loose fiber - second loose fiber - third loose fiber - colored cotton fiber. The spinning steps after the drawing process include the roving process and the spinning process of the third sliver in sequence to obtain ring-dyed yarn.

[0042] S34: Roving, roving twist of 4.4 twists / 10cm, back zone draft ratio set to 1.2 times, feed tension draft ratio set to 1.036 times, nip spacing set to 5.8mm, roving dry weight basis weight of 3.9g / 10m, and mechanical draft ratio set to 8 times.

[0043] S35: Spinning: After further stretching the roving, it is twisted into a spinneret by a twisting machine. In the spinning process, the back zone draft ratio is 1.15, the nip spacing is 2.5mm, the twist is 60-90 twists / 10cm, the roller spacing is 20x37mm, and the spindle speed is 10000-13000rpm.

[0044] This produces a yarn with a ring-dye-like effect. Steps S31 and S32 help protect the loose fibers with lower strength, effectively reducing damage to the loose fibers during machine processing. Combined with the colored cotton fibers forming the surface of the yarn, the yarn has better strength.

[0045] When making denim fabric, this yarn can be used as the warp yarn. The yarn obtained above is then subjected to warping, sizing, weaving, singeing, desizing, and pre-shrinking treatments to obtain denim fabric. This denim fabric is made from waste textiles combined with long-staple cotton. The distressed effect of denim fabric is created in advance during the dyeing, washing, and drawing of the fibers, so there is no need for further washing and distressing, and the low-strength loose fibers are protected from harsh chlorine bleaching and enzyme bleaching.

[0046] Implementation Cases

[0047] White waste pure cotton fabric was broken into loose fibers and divided into three groups: B, C, and D. Xinjiang long-staple cotton was purchased separately as group A. All four groups of fibers were dyed with the same concentration of indigo dye (indigo dye content 2.6 g / L, sodium hydrosulfite content 1.4 g / L, sodium hydroxide content 2.4 g / L, dispersant content 2 g / L). Group A was then washed with water for 20 minutes and dried. Group B was treated with a washing solution containing 2 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 10 minutes and then dried. Group C was treated with a washing solution containing 4 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 15 minutes and then dried. Group D was treated with a washing solution containing 6 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 20 minutes and then dried. Group A was then opened and combed according to standard process requirements. For groups B, C, and D, during opening, the batter lowering distance of the cotton picker is 2mm per stroke, the rotation speed is set to 900r / min, the rotary carriage speed is set to 2.3r / min, the blade extends 3mm beyond the ribs, the blade speed is set to 760r / min, the fan speed is set to 920r / min, the interval between the batter and the balance roller is 9mm, the lap roller speed is set to 11r / min, and the lap dry weight is 345g / m. During carding, the cylinder-licker-in distance is set to 11 filaments, the cylinder-doffer distance is set to 5 filaments, the cylinder speed is set to 278r / min, the licker-in speed is set to 580r / min, the doffer speed is set to 15.2r / min, the flats speed is set to 181mm / min, and the carding dry weight is 18.5g / 5m. During the drawing process, in the first pass, eight slivers combed from group A fibers are combined into one second sliver A2, eight slivers combed from group B fibers are combined into one second sliver B2, eight slivers combed from group C fibers are combined into one second sliver C2, and eight slivers combed from group D fibers are combined into one second sliver D2. In the second pass, the second slivers are arranged in the order A2-B2-C2-D2-D2-C2-B2-A2 and then drawn together. After the roving and spinning processes, a ring-dyed yarn with a count of 12S is obtained. The breaking strength of this yarn is tested according to GB / T 3916-2013, and the breaking strength is measured to be 752 cN. Using this yarn as the warp and 12S ordinary cotton yarn as the weft, after warping and sizing, the fabric is woven into a 3-up-1-down twill weave. The fabric is then singed, desized, and pre-shrinked to obtain denim fabric with a weight of 11.6 oz. The fabric is subjected to a tensile breaking strength test, and the warp breaking strength of the fabric is 428 N, which meets the requirements of the denim clothing standard FZ / T 81006-2017.

[0048] Comparative Example 1

[0049] White waste pure cotton fabric was broken into loose fibers and divided into four groups: A, B, C, and D. Each group was dyed with the same concentration of indigo dye (2.6 g / L indigo dye, 1.4 g / L sodium hydrosulfite, 2.4 g / L sodium hydroxide, and 2 g / L dispersant). Group A was then washed with water for 20 minutes and dried. Group B was treated with a washing solution containing 2 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 10 minutes and then dried. Group C was treated with a washing solution containing 4 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 15 minutes and then dried. Group D was treated with a washing solution containing 6 g / L hydrogen peroxide and 1 g / L sodium hydroxide for 20 minutes and then dried. Groups A, B, C, and D were then opened and combed according to standard process requirements. During the drawing process, in the first pass, eight slivers combed from group A fibers are combined into one second sliver A2, eight slivers combed from group B fibers are combined into one second sliver B2, eight slivers combed from group C fibers are combined into one second sliver C2, and eight slivers combed from group D fibers are combined into one second sliver D2. In the second pass, the second slivers are arranged in the order A2-B2-C2-D2-D2-C2-B2-A2 and then drawn together. After the roving and spinning processes, a ring-dyed yarn with a count of 12S is obtained. The breaking strength of this yarn is tested according to GB / T 3916-2013, and the breaking strength is measured to be 578 cN. The yarn has low strength. Using this yarn as the weft yarn and ordinary 12S cotton yarn as the warp yarn, after warping and sizing, it is woven into a fabric blank with a three-up-one-down twill weave. The fabric blank is singed, desized, and pre-shrinked to obtain the fabric of Comparative Example 1. The fabric weight is 11.8 oz and its breaking strength is tested to be 312 N.

[0050] Comparative Example 2

[0051] Using Xinjiang long-staple cotton as raw material, ordinary cotton yarn with a count of 12S was spun using conventional methods. The breaking strength of this yarn was tested according to GB / T 3916-2013, and the result was 946 cN. Using this yarn as both warp and weft, after warping and dyeing, the fabric was woven into a 3 / 1 twill weave. The fabric was then singed, desized, washed, and pre-shrinked to obtain denim fabric, with a breaking strength of 518 N.

[0052] Therefore, the embodiments of this application can use waste textiles to produce ring-dyed yarn, which can be further made into denim fabric. The fabric strength is close to that of fabric made from normal raw materials, and it can be pre-washed and faded, which is beneficial for creating a distressed appearance for denim fabric and reducing color differences in subsequent garment making and washing. During spinning, high-quality long-staple cotton fibers are selected for the outer layer to wrap the weaker loose fibers, effectively improving the strength and hand feel of the yarn. This ensures that the yarn from recycled waste textiles meets the requirements for weaving, resulting in a fabric of good quality. Through specific dyeing, fading, and drawing processes, the yarn color gradually lightens from the outside to the inside, achieving an effect similar to traditional yarn after sizing and ring dyeing. The embodiments of this application focus on dyeing and fading the fibers rather than the yarn or fabric, effectively reducing the chemicals required in the dyeing process. This helps to break through the traditional denim fabric production process and open up new avenues for the reuse of waste textiles.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for making a yarn-like ring-dyed fabric from waste pure cotton fabric, characterized in that, The method comprises the following steps: breaking white waste pure cotton fabric into loose fibers; dyeing the loose fibers into first, second and third loose fibers with color gradually deepening, and taking long cotton to dye into colored cotton fibers with color deeper than the third loose fibers; spinning to obtain the ring-like dyed yarn; wherein in the drawing process, slivers formed by the colored cotton fibers, the first, second and third loose fibers are arranged in the same plane in the order of color from deep to shallow and then from shallow to deep; in the roving process, the roving twist is 4.4 twists / 10 cm, the back zone draft ratio is set to 1.2 times, the feed strip tension draft ratio is set to 1.036 times, the nip gauge is set to 5.8 mm, the roving dry weight is 3.9 g / 10 m, and the mechanical draft ratio is set to 8 times; in the spinning process, the back zone draft ratio is 1.15 times, the nip gauge block is 2.5 mm, the twist is 60-90 twists / 10 cm, the roller gauge is 20x37 mm, and the spindle speed is 10000-13000 rpm; the drawing process is two-drawing, the first drawing: 6 or 8 slivers of the same fiber are combined into one second sliver; the second drawing: 8 second slivers are combined into one third sliver in the transverse arrangement order of colored cotton fibers-third loose fibers-second loose fibers-first loose fibers-first loose fibers-second loose fibers-third loose fibers-colored cotton fibers; the spinning process further comprises, after the drawing process, a roving process and a spinning process of the third sliver in sequence.

2. The method according to claim 1, wherein the waste pure cotton fabric is used to produce the yarn-like ring-dyed fabric. The step of dyeing the loose fibers into first, second and third loose fibers with color gradually deepening, and taking long cotton to dye into colored cotton fibers with color deeper than the third loose fibers comprises: dyeing the long cotton and the loose fibers with the same process, then washing the dyed long cotton with clean water, and drying to obtain the colored cotton fibers; dividing the dyed loose fibers into three groups and treating them with different concentrations of washing and fading liquid to obtain the first, second and third loose fibers after drying.

3. The method according to claim 2, wherein the waste pure cotton fabric is prepared into the ring-like yarn by the method, characterized in that, The loose fibers treated with 2 g / L hydrogen peroxide as the washing and fading liquid become the third loose fibers after drying, the loose fibers treated with 4 g / L hydrogen peroxide as the washing and fading liquid become the second loose fibers after drying, and the loose fibers treated with 6 g / L hydrogen peroxide as the washing and fading liquid become the first loose fibers after drying.

4. The method according to claim 3, wherein the waste pure cotton fabric is used to produce the yarn-like ring-dyed fabric. The washing and fading liquid contains 1 g / L sodium hydroxide.

5. The method for producing ring-dyed yarn from waste pure cotton fabric according to claim 3, characterized in that, The time for the loose fibers to become the third loose fibers to be treated by the washing and fading liquid is 10 min, the time for the loose fibers to become the second loose fibers to be treated by the washing and fading liquid is 15 min, and the time for the loose fibers to become the first loose fibers to be treated by the washing and fading liquid is 20 min.

6. The method of claim 1, wherein the waste pure cotton fabric is a woven fabric. The spinning step includes an opening process and a carding process before the drawing process, and the requirements for the opening process of the first, second and third loose fibers are that the distance of the beater falling is 2mm each time, the rotating speed is set to 900r / min, the speed of the rotating trolley is set to 2.3r / min, the blade is extended by 3mm, the speed of the blade is set to 760r / min, the speed of the fan is set to 920r / min, the distance between the beater and the flat roller is 9mm, the speed of the lap roller is set to 11r / min, and the dry weight of the lap is set to 345g / m.

7. The method according to claim 6, wherein the waste pure cotton fabric is prepared into the ring-like yarn. The requirements for the carding process of the first, second and third loose fibers are that the distance between the cylinder and the licker-in is set to 11 English silk, the distance between the cylinder and the doffer is set to 5 English silk, the speed of the cylinder is set to 278r / min, the speed of the licker-in is set to 580r / min, the speed of the doffer is set to 15.2r / min, the speed of the flat is set to 181mm / min, and the dry weight of the carded cotton is set to 18.5g / 5m.

8. A yarn characterized in that, The yarn is made by the method of any one of claims 1 to 7.

9. A fabric, characterized by The yarn is used as the warp yarn.