Method for producing recycled spun yarn and textile product containing the spun yarn

Abstract

To provide a method for producing a recycled spun yarn capable of being efficiently and sufficiently opened when recycled, and to provide a textile product containing the spun yarn.SOLUTION: The spun yarn is produced by using a flame-retardant recycled fiber that is obtained by applying an oil agent to a woven fabric containing a flame-retardant spun yarn and having a twist coefficient×woven fabric packing density of 4.5 or less or a textile product made of the woven fabric before or after cutting treatment to give a cut product and opening the cut product.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing recycled spun yarn that enables efficient and sufficient fibrillation during recycling, and a fiber product containing the spun yarn.

Background Art

[0002] Conventionally, flame-retardant fabrics containing flame-retardant fibers such as wholly aromatic polyamide fibers have been used as work clothes worn by people engaged in work that may be exposed to flames, such as in the fire protection, electric power, and chemical industries, because of their excellent heat resistance and flame retardancy. Although flame-retardant fabrics use flame-retardant fibers with excellent properties, their performance deteriorates with use, and they become unusable due to dirt, abrasion, tearing, fraying, etc., and ultimately are discarded. Also, cutting scraps are generated during each stage of manufacturing flame-retardant fabrics and when sewing work clothes using these fabrics. As a result, scraps generated in these respective processes and used products are produced as waste. And most of such process scraps and used products are used industrially, and unlike generally used products, they are hardly recycled, and most of them are incinerated or landfilled.

[0003] On the other hand, in recent years, it has been required to suppress resource consumption and reduce the environmental load. Specifically, in the fiber industry, used products of general-purpose fibers are recycled, such as those called old rags or waste fibers like shredded fibers. For example, in the recycled market, the waste fibers are used as material recycling materials, processed into cotton or yarn, and fiber products such as felt and work gloves are made.

[0004] Similarly, it has been required to apply the same recycling methods as those for general-purpose fiber products to the process scraps and used products of flame-retardant fabrics (for example, Patent Documents 1 and 2). However, compared with fabrics made of general-purpose fibers, flame-retardant fabrics are excellent in heat resistance and flame retardancy, and may also have high tensile strength and cut resistance. When using a known fiber-opening machine under conventional conditions, problems occur, and it is difficult to perform efficient and sufficient fiber opening.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a method for producing recycled spun yarn that enables efficient and sufficient fiber opening during recycling, and a fiber product containing the spun yarn.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventor has completed the present invention. Thus, the following invention is provided.

[0008] 1. A method for producing recycled spun yarn, comprising producing a spun yarn using flame-retardant recycled fibers obtained by applying an oil agent to a fabric containing a flame-retardant spun yarn and satisfying the following formula (1) or a fiber product using the fabric, before or after cutting, to obtain a cut product, and then opening the cut product. Twist coefficient × Fabric packing density ≤ 4.5 ··· (1) 2. The method for producing recycled spun yarn according to 1 above, wherein the oil agent contains an alkyl phosphate metal salt. 3. The method for producing recycled spun yarn according to 1 or 2 above, wherein the oil agent contains a silicone-based component. 4. The method for producing a recycled spun yarn according to any one of 1 to 3 above, wherein the adhesion amount of the sizing agent is 0.2 to 1.0% by weight based on the weight of the flame-retardant recycled fiber. 5. The method for producing a recycled spun yarn according to any one of 1 to 4 above, wherein the flame-retardant recycled fiber is mixed at a ratio of 10 to 90% by weight of the whole spun yarn before or during spinning. 6. The method for producing a recycled spun yarn according to any one of 1 to 5 above, wherein the flame-retardant recycled fiber contains 10% by weight or more of short fibers having a length of 20 mm or more based on the weight of the spun yarn. 7. The method for producing a recycled spun yarn according to any one of 1 to 6 above, wherein the flame-retardant recycled fiber contains 10% by weight or more of short fibers having a length of 40% or more of the short fiber length used in the fabric based on the weight of the spun yarn. 8. A fiber product containing a spun yarn obtained by the production method according to any one of 1 to 7 above.

Advantages of the Invention

[0009] According to the present invention, there are provided a method for producing a recycled spun yarn capable of efficient and sufficient fiber opening during recycling, and a fiber product containing the spun yarn.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail. A fabric suitable for recycling used in the present invention (sometimes referred to as a "flame-retardant spun yarn fabric") contains a flame-retardant spun yarn, and it is important to satisfy the following formula (1) by the twist coefficient calculated from the twist number and count of such a spun yarn, the fabric structure of the fabric, and the fabric packing density calculated from the count of the spun yarn. Twist coefficient × Fabric packing density ≤ 4.5 (1)

[0011] Here, the twist coefficient can be calculated by K = T / √n, where K is the twist coefficient, T is the number of twists per inch (2.54 cm), and n is the English cotton count. Such a twist coefficient K is preferably in the range of 2.5 to 6.0 from the viewpoints of the physical properties and flexibility of the fabric. In particular, it is preferably 2.5 to 4.5 in the case of single yarn and 3.0 to 6.0 in the case of double yarn. The spun yarn may be single yarn or double yarn, and the twist coefficient is calculated from the number of twists of the final yarn. In the case of a single yarn fabric (a fabric made of single yarn spun yarn), it is the twist coefficient obtained from the lower twist number of the single yarn, and in the case of a double yarn fabric (a fabric made of double yarn spun yarn), it is the twist coefficient obtained from the upper twist number of the double yarn.

[0012] Also, the fabric packing density is determined as follows. Fabric packing density = (ta1 + ta2) / (tm1 + tm2) Here, ta1 is the amount actually occupied by the yarn in one complete repeat, which is the warp density per cm (threads / cm). Similarly, ta2 is the amount actually occupied by the yarn in one complete repeat, which is the weft density per cm (threads / cm). tm1 is the amount theoretically occupied by the maximum yarn in one complete repeat in the warp direction, and tm2 is the amount theoretically occupied by the maximum yarn in one complete repeat in the weft direction. tm can be expressed by the following formula. tm = e / ((e - i)×3.14×d / 4 + 2id) Here, e is the number of warp yarns (weft yarns in the case of tm2) in one complete repeat, and i is the number of warp (weft in the case of tm2) intersections in one complete repeat. In the present invention, it is preferable that e and i have the same value for warp and weft, but they may be different.

[0013] Also, d is the diameter of the yarn and can be expressed by the following formula. d(cm) = 0.00357×√((tex / (φ×ρf)) Here, tex is the value obtained by converting the spun yarn count to tex, φ is the packing rate of the yarn, and ρf is the specific gravity of the fiber. The packing rate φ of the yarn is calculated as 1 for simplicity in the present application.

[0014] When the twist number of the spun yarn increases, it becomes difficult to fibrillate by the disintegration treatment and the fluffing treatment. Also, if the fabric packing density is too high, there is a possibility that it becomes difficult to fibrillate by the disintegration treatment and the fluffing treatment as well. When the product of the twist coefficient and the fabric packing density is 4.5 or less (more preferably 0.1 to 4.0), fibrillation in the disintegration treatment and the fluffing treatment becomes easy, which is preferable. Here, the spun yarn contains a flame-retardant fiber. In that case, it is preferable that the limiting oxygen index measured by the JIS L1091-1999 E method of the flame-retardant fiber is 25 or more.

[0015] Examples of such flame-retardant fibers include meta-aramid fibers (meta-type wholly aromatic polyamide fibers), para-aramid fibers (para-type wholly aromatic polyamide fibers), polyparaphenylene benzoxazole fibers, polybenzimidazole fibers, polyimide fibers, polyetherimide fibers, polyamideimide fibers, carbon fibers, polyphenylene sulfide fibers, polyvinyl chloride fibers, flame-retardant rayon, modacrylic fibers, flame-retardant acrylic fibers, flame-retardant polyester fibers, flame-retardant vinylon fibers, melamine fibers, fluorine fibers, flame-retardant wool, flame-retardant cotton, etc. One or more of these flame-retardant fibers can be used.

[0016] Among them, from the viewpoint of showing an excellent limiting oxygen index and excellent mechanical properties, meta-aramid fibers, that is, metaphenylene isophthalamide fibers (commercially available products include "Teijin Conex" and "Teijin Conex Neo" (trademark names) manufactured by Teijin Limited, "Nomex" (trademark name) manufactured by DuPont, etc.) are useful. Furthermore, it is also preferable to mix para-aramid fibers, that is, paraphenylene terephthalamide fibers (commercially available products include "Twaron" (trademark name) manufactured by Teijin Limited, "Kevlar" (trademark name) manufactured by Toray DuPont Co., Ltd., etc.), coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (commercially available products include "Technora" (trademark name) manufactured by Teijin Limited, etc.).

[0017] These flame-retardant fibers may contain additives such as antioxidants, ultraviolet absorbers, heat stabilizers, flame retardants, titanium oxide, colorants, and inert fine particles, as long as the object of the present invention is not impaired.

[0018] The spun yarn preferably consists only of the above-mentioned flame-retardant fibers, but may contain non-flame-retardant fibers (fibers having a limiting oxygen index of less than 25 as measured by the JIS L 1091-1999 E method). In this case, the content of the flame-retardant fibers is preferably 40% by weight or more of the whole yarn. Examples of the non-flame-retardant fibers include polyester fibers, nylon fibers, rayon fibers, polynosic fibers, lyocell fibers, acrylic fibers, vinylon fibers, cotton, hemp, and wool. One or more of these non-flame-retardant fibers can be used.

[0019] These non-flame-retardant fibers may contain additives such as antioxidants, ultraviolet absorbers, heat stabilizers, flame retardants, titanium oxide, colorants, inert fine particles, and conductive particles, as long as the object of the present invention is not impaired.

[0020] Since the flame-retardant spun yarn fabric has the above configuration, efficient and sufficient fibrillation is possible when recycling. The flame-retardant spun yarn fabric includes unused flame-retardant spun yarn fabrics, used flame-retardant spun yarn fabrics, process scraps generated during the production of the fabric, and sewing scraps generated during sewing.

[0021] In the present invention, the flame-retardant spun yarn fabric or a fiber product using the fabric (hereinafter sometimes collectively referred to as "recycling fabric product") is washed as necessary, and then an oil agent is applied before and / or after cutting to obtain a cut product, and a recycled spun yarn is produced using the flame-retardant recycled fibers obtained by fibrillation of the cut product.

[0022] Here, the textile product is not particularly limited as long as it includes the above-mentioned flame-retardant spun yarn fabric. Specifically, flame-retardant work clothes, fire-fighting suits, work gloves, industrial safety materials (fabrics), etc. containing flame-retardant spun yarns can be mentioned. In such flame-retardant spun yarn products, it is preferable that the above-mentioned flame-retardant spun yarns are used alone. However, it may also contain yarns other than flame-retardant spun yarns, preferably spun yarns. In this case, the content of the flame-retardant spun yarn is preferably 50% by weight or more of the entire textile product. The used flame-retardant spun yarn products used in the present invention include not only the used products of the above-mentioned flame-retardant spun yarn products, but also fiber scraps and defective products generated in the process of manufacturing flame-retardant spun yarn products. Hereinafter, each step will be described in detail.

[0023] First, it is preferable to wash the above-mentioned used recycled textile products in advance. By this washing treatment, in addition to the dirt attached to the used recycled textile products, impurities and oil components are removed. As a result, the occurrence of equipment troubles can be suppressed, and efficient recycling treatment can be performed. Also, performing the washing treatment is preferable from the viewpoint of improving the quality of the recycled product. Also, it is possible to check whether the used recycled textile products as raw materials can be reused or not, and to check whether various miscellaneous substances are contained in the products or not.

[0024] The washing method is not particularly limited, and known means may be used. Among them, in addition to dissolving or separating dirt and oil using detergents, solvents, etc., it is preferable to adopt a washing method that simultaneously gives an impact to knock off dirt to the object to be washed together with conventional rotary washing, or an overmayer type dyeing machine. Also, in order to apply an oil agent in the next step, it is preferable to perform a drying treatment.

[0025] In the present invention, it is important to apply an oil agent to the recycled fabric product in at least one of before and after the cutting (crushing) process described later. By applying the oil agent in this way, it is possible to suppress the generation of static electricity in the crushing process, the fiber opening process, and the spinning process, and there is an advantage that the above-mentioned processes can be performed smoothly. The oil agent is not particularly limited as long as it is an oil agent mainly composed of an oil agent used in normal spinning. For example, the oil agent preferably contains an antistatic agent such as an alkyl phosphate metal salt. It is also preferable to contain a silicone-based component as a smoothing agent. The amount of the oil agent applied is preferably 0.2 to 1.0% by weight based on the weight of the flame-retardant recycled fiber. More preferably, it is 0.2 to 0.8% by weight, and particularly preferably 0.2 to 0.6% by weight.

[0026] The flame-retardant recycled fiber thus obtained has substantially no crimp, and the number of crimps measured by JIS L1015:2010 is 1.0 or less per inch (2.54 cm).

[0027] Here, due to the crushing process, the used recycled fabric product is mechanically decomposed and separated into threads, pieces, and cotton-like forms. Therefore, the fiber opening process is easier and the cotton-like formation can be promoted compared to directly performing the fiber opening process on the product. In the present invention, the crushing process is not particularly limited as long as the above object can be achieved, and known means may be used. The present invention aims to recycle the recycled fabric product particularly as a spun yarn. The shorter the length of the short fibers of the cotton-like material obtained in the subsequent fiber opening process, the higher the recovery of the tensile strength and the more likely it can be regenerated into a spun yarn. Therefore, in the crushing process of the present invention, a process that increases the content ratio of short fibers as close as possible to the original length is preferable.

[0028] The crushing process may include a cutting process of roughly cutting the recycled textile product. In this case, according to the form of the product, it is preferable to increase the cutting interval so that the content ratio of short fibers is as high as possible and close to the original length. For example, cut (at intervals) longer than the length of the short fibers of the spun yarn used in the recycled textile product. It is also preferable to bite into, tear, and pull out the product to tear and crush it. Furthermore, scraping and shaving may be carried out in one step up to the fibrillation process described later.

[0029] Also, the conditions for the fibrillation process vary depending on the shape of the recycled textile product, the type of flame-retardant fiber used in the product, or the type of fibrillation machine, etc. Appropriate tests can be carried out according to the raw material recycled textile product, and appropriate conditions can be determined. However, it is preferable to select the fibrillation conditions so that the cotton-like material obtained by the fibrillation process contains short fibers with a length of 20 mm or more at 10% by weight or more based on the spun yarn weight. It is also preferable to select the fibrillation conditions so that the short fibers having a length of 40% or more of the short fiber length of the spun yarn used in the original product are contained at 10% by weight or more based on the spun yarn weight. As described above, the more short fibers having a long length, in other words, a length close to the original fiber length, the higher the recovery of the tensile strength of the recycled spun yarn (the ratio of the tensile strength of the recycled flame-retardant spun yarn to the tensile strength of the commercially available spun yarn) can be. The fiber length distribution can be easily measured by a staple diagram according to "JIS L 1015 - 2010 8.4.1 Method A". Note that fibrillation can be carried out with a known defurring machine, fibrillation machine, etc.

[0030] Next, the cotton-like material obtained by the above fibrillation treatment is spun to regenerate a spun yarn. In the present invention, before spinning, unused short fibers may be mixed with the cotton-like material obtained by fibrillating the crushed material at a ratio of 90% by weight or less (more preferably 10 to 90% by weight, still more preferably 10 to 70% by weight) of the whole. By mixing the unused short fibers, there is an advantage that the tensile strength of the recycled spun yarn can be more effectively recovered. As the unused short fibers, crimped short fibers are preferable. This is because the presence of crimp makes it easier for strand or tow-like fibers to be fibrillated. Also, short fibers having a length of about 30 mm or more (more preferably 30 to 200 mm) are preferable. If the length of the unused short fibers is long, more cotton-like material can be obtained in the present invention, which is more entangled and longer, and the connection effect is enhanced, so that a regenerated heat-resistant high-functional spun yarn with more recovered tensile strength can be obtained.

[0031] The unused short fibers used in the present invention include (a) the staple of commercially available flame-retardant fibers, or (b) short fibers obtained from fiber scraps and scraps generated in the process of manufacturing products made of long flame-retardant fibers or the long fibers. These are preferably those having a length of 30 to 200 mm and being easily fibrillated with crimp. The short fibers of (b) can be obtained by cutting the fiber scraps and scraps generated in the process of manufacturing products made of long flame-retardant fibers or the long fibers.

[0032] The method of mixing the unused short fibers with the cotton-like material is not particularly limited, and for example, a known mixing method such as a method of blending cotton and polyethylene terephthalate fibers may be used. Also, the mixing of the unused short fibers may be preferably carried out during spinning, preferably in the carding process. Also, conductive fibers may be mixed at a ratio of 0.1 to 5% by weight of the whole spun yarn before or during spinning.

[0033] A method for producing a spun yarn from a cottony substance or a mixture of a cottony substance and unused short fibers (hereinafter simply referred to as a spinning method) is well established in the art, and thus may be followed accordingly. Specific examples of the spinning method include methods such as a cotton spinning method, a carding method, a wool spinning method, a hemp spinning method, a silk spinning method, or a rayon spinning method. Further, these methods may be appropriately combined. Among them, in the present invention, it is preferable to use a cotton spinning method, a carding method, or a wool spinning method.

[0034] More specifically, as the above spinning method, a spinning method including a cotton mixing process, a carding process, a pre-spinning process, and a fine-spinning process is given as a preferred example. Hereinafter, each process of the cotton spinning method will be described.

[0035] The carding process is a process of separating the cottony substance having a low bulk density in the above fiber opening treatment into individual fibers finally and producing a sliver which is an aggregate of infinitely long fibers in the form of a rod-like string. Such a carding process can be carried out using a known carding machine. Among them, in the present invention, it is preferable to carry out the carding process using a flat card. The sliver obtained in the present invention preferably contains 10% by weight or more of short fibers having a length of about 20 mm or more and / or 10% by weight or more of short fibers having a length of 40% or more of the short fiber length of the spun yarn used in the textile product for recycling. The fiber length distribution can be easily measured by a staple diagram in accordance with "JIS L 1015-2010 8.4.1 Method A".

[0036] The roving process is an intermediate adjustment process to make the sliver produced in the carding process suitable for the spinning process in terms of appropriate fiber arrangement and thickness. Usually, several sets of top and bottom rollers and other devices are attached to stretch the sliver and improve the fiber arrangement (this is called drafting). The roving process is further divided into the drawing process and the roving process. The drawing process is a process that mainly performs drafting centered on improving the arrangement of the sliver with poor fiber arrangement immediately after the carding process, and is usually repeated multiple times. After that, the roving process is a process that sequentially and appropriately thins the thickness of the sliver. The spinning process refers to a process that supplies the roving obtained in the roving process and finally makes it the desired thickness (count), and performs an operation of adding twist and winding it up if desired. Usually, in this process, twisting and winding are performed simultaneously.

[0037] In the recycled spun yarn obtained as described above, it is preferable that the twist factor of the spun yarn is 2.5 to 6.0. Also, it is preferable to contain 10% by weight or more of short fibers having a length of 20 mm or more based on the weight of the spun yarn. Further, it is preferable to contain 10% by weight or more of short fibers having a length of about 40% or more of the short fiber length of the spun yarn used in the recycled fabric product based on the weight of the spun yarn.

[0038] As described above, the more long short fibers are contained, the higher the recovery of the tensile strength can be enhanced. The fiber length distribution can be easily measured by a staple diagram in accordance with JIS L 1015-2010 8.4.1 Method A.

[0039] Recycled spun yarn containing 10% by weight or more of short fibers with a length of about 20 mm or more has the effect that the ratio of the tensile strength to the tensile strength of the unused spun yarn is high, and as a result, it has the advantage that it can be used for a wider range of applications. Specifically, the recycled spun yarn has a tensile strength of 40 to 100%, preferably 50 to 100%, more preferably 60 to 100% with respect to the tensile strength of the spun yarn of the unused fiber. The tensile strength of the spun yarn is measured according to "JIS L 1095:2010 9.5". Further, the recycled spun yarn can be made into a finer yarn and has advantages such as being soft and having a good texture. Here, the fiber length distribution can be easily measured by a staple diagram according to "JIS L 1015:2010 8.4.1 Method A".

[0040] The recycled spun yarn obtained in the present invention contains flame-retardant fibers, so it can be applied to various applications that take advantage of the characteristics of such fibers. For example, a fabric can be produced by weaving or knitting the recycled spun yarn. Such a woven fabric is excellent in flame retardancy and can be used for various applications as a flame-retardant sheet. Also, fiber products such as clothing can be produced using such a fabric. In particular, it is preferable to use the recycled spun yarn of the present invention for protective clothing applications. The protective clothing applications are not particularly limited as long as they are clothing for the purpose of protecting the body of the person wearing them, and examples include flame-retardant work clothes, fire-fighting suits, outdoor and sports clothes. Further, it can be knitted and woven using the recycled spun yarn of the present invention and can be used for protective clothing, gloves, and material applications.

Examples

[0041] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these disclosed examples. Each measurement item in the examples was measured by the following method. Note that 1 inch is 2.54 cm.

[0042] (1) Twist coefficient K The twist factor was calculated by K = T / √n. Here, K is the twist factor, T is the number of twists per inch (2.54 cm), and n is the English cotton count.

[0043] (2) Fabric filling density The fabric filling density was calculated by the following formula. Fabric filling density = (ta1 + ta2) / (tm1 + tm2) Here, T is the filling degree of the fabric, ta1 is the amount actually occupied by the yarn in one complete weave in the warp direction, which is the warp density per centimeter (threads / cm). Similarly, ta2 is the amount actually occupied by the yarn in one complete weave in the weft direction, which is the weft density per centimeter (threads / cm). tm1 is the amount theoretically occupied by the maximum yarn in one complete weave in the warp direction, and tm2 is the amount theoretically occupied by the maximum yarn in one complete weave in the weft direction. tm was calculated by the following formula. tm = e / ((e - i)×3.14×d / 4 + 2id) Here, e is the number of yarns in the warp direction (or weft direction) of one complete weave, i is the number of intersections in the warp direction (or weft direction) of one complete weave. d is the diameter of the yarn and was calculated by the following formula. d(cm) = 0.00357×√((tex / (φ×ρf)) Here, tex is the value obtained by converting the spinning yarn count to tex, φ is the filling rate of the yarn, and ρf is the specific gravity of the fiber. The filling rate φ of the yarn was calculated as 1 for simplicity.

[0044] (3) Fiber length distribution The distribution of fiber lengths was measured using a staple diagram in accordance with JIS L 1015:2010 8.4.1 Method A. Also, the ratio of fibers with a length of 20 mm or more in the examples was calculated from the obtained staple diagram as described in the examples of Japanese Patent No. 3782061.

[0045] (4) Flame retardancy of fibers The limiting oxygen index (LOI) defined in JIS 1091:1999 E-2 was measured.

[0046] (5) Degree of fiber opening of recycled fibers The fibrillation degree of the recycled fiber was calculated by the following formula. Fibrillation degree (%) = (Wt - W) / Wt × 100 Here, W is the weight (g) of the unfibrillated fiber remaining in the state of yarn etc. in the recycled fiber. Also, Wt is the total weight (g) of the recycled fiber. Thus, the ratio (%) of the fibrillated fiber in the recycled fiber can be represented.

[0047] (6) Number of crimps The number of crimps was measured according to JIS L 1015:2010.

[0048] (7) Amount of oil agent attached After weighing 2 g of raw cotton (W1) and an aluminum dish (W2), using a rapid extractor, it was immersed in 15 ml of ethanol solvent, pressed, and the oil agent was extracted into the aluminum dish. After only the ethanol on the aluminum dish was evaporated to dryness, the aluminum dish (W3) was weighed, and the amount of oil agent attached (opu, unit; %) was determined from the following formula. opu (%) = ((W3 - W2) / W1) × 100

[0049] (8) Card passing property Under the conditions of 25°C and 65% RH, at 300 grains / yard (0.9144 m) and 12 rpm, the clogging of the coiler tube at the carding outlet and the sagging of the sliver between the calendar roll and the coiler were observed. Those without problems overall were judged as ○, those with particularly poor spinning performance and unable to be processed smoothly as ×, and those in the middle as △.

[0050] (9) Number of defects (neps) The number of defects was measured using a yarn unevenness tester equipped with a defect counting device based on JIS L1095 B method:2010, and the number of yarn defects (neps) at +200% of the average thickness was measured. The number of yarn defects (neps) is expressed by rounding to the integer part per 1000 m.

[0051] [Example 1] As a textile product for recycling to be recycled, a flame-retardant work clothing fabric composed of 95% by weight of meta-aramid fiber for work clothing and 5% of para-aramid fiber was used. Such a fabric is composed of 95% by weight of polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark name) manufactured by Teijin Limited) and 5% of coparaphenylene-3,4'-oxydiphenylene terephthalamide fiber ("Technora" (trademark name) manufactured by Teijin Limited), and is made of a 40-count / 2-ply flame-retardant spun yarn. The number of twists per inch in the S twist direction was 19.8 turns / inch. The fabric weave is twill weave (2 / 2), with a warp density of 86 threads / inch and a weft density of 75 threads / inch. Each parameter required for the fabric packing density was e = 4, i = 2, and d = 0.0165. The twist coefficient of this fabric was 4.43, the fabric packing density was 0.73, and the twist coefficient × fabric packing density was 3.23. The fabric was cut into approximately 5 cm squares, and subjected to a washing treatment of washing and drying, and an antistatic and smoothing improver was applied. Such an improver contained potassium lauryl phosphate as an antistatic agent and a silicone-based component as a smoothing agent. The amount of the improver adhering to the flame-retardant recycled fiber was 0.35% by weight. Thereafter, the cut flame-retardant fabric was subjected to a crushing treatment and then an opening treatment with a garnett machine. The opening property of the obtained recycled fiber (including thread-like materials with insufficient opening) was good. 30% by weight of this fiber was mixed with 70% of unused polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark name), CN) having a fineness of 1.7 dtex and a fiber length of 51 mm, and subjected to a carding process, a drawing process, and a roving process to produce a 20-count / single-ply flame-retardant spun yarn according to the present invention. The opening property of the obtained recycled fiber, the ratio of fibers having a fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0052] [Comparative Example 1] As the textile product for recycling to be recycled, the same product as in Example 1 was used. The treatment of the fabric was carried out in the same manner as in Example 1 except that no improver was applied, and a 20-count / single-ply flame-retardant spun yarn according to the present invention was produced. The opening property of the obtained recycled fiber, the ratio of fibers having a fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0053] [Example 2] As a textile product for recycling to be recycled, a flame-retardant work clothing fabric composed of 95% by weight of meta-aramid fiber and 5% by weight of para-aramid fiber for work clothing was used. Such a fabric is composed of 95% by weight of polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark) manufactured by Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fiber ("Technora" (trademark) manufactured by Teijin Limited), and is made of a 36-count / 2-ply flame-retardant spun yarn. The number of twists per inch in the Z-twist direction was 19.8 turns / inch (Z-twist). The fabric weave is plain weave, with a warp density of 60 threads / inch and a weft density of 49 threads / inch. Each parameter required for the fabric packing density was e = 2, i = 2, and d = 0.0174. The twist coefficient of the 2-ply yarn of this fabric was 4.66, the fabric packing density was 0.75, and the twist coefficient × fabric packing density was 3.48. The treatment of the fabric was carried out in the same manner as in Example 1 to produce a 20-count / single-ply flame-retardant spun yarn according to the present invention. The fibrillation property of the obtained recycled fiber, the ratio of the fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0054] [Comparative Example 2] The textile product for recycling to be recycled was the same as that in Example 2. The treatment of the fabric was carried out in the same manner as in Example 2, except that no oil agent was applied, to produce a 20-count / single-ply flame-retardant spun yarn according to the present invention. The fibrillation property of the obtained recycled fiber, the ratio of the fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0055] [Example 3] As a textile product for recycling to be recycled, a flame-retardant work clothing fabric composed of 95% by weight of meta-aramid fiber and 5% by weight of para-aramid fiber for work clothing was used. Such a fabric is composed of a flame-retardant spun yarn No. 40 / monofilament composed of 95% by weight of polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark) manufactured by Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fiber ("Technora" (trademark) manufactured by Teijin Limited), and the number of twists in the lower direction was 24.0 turns / inch (Z twist). The fabric weave is plain weave, and the fabric has a warp density of 53 threads / inch and a weft density of 53 threads / inch. Each parameter required for the fabric packing density was e = 2, i = 2, d = 0.0117. The twist coefficient of the monofilament of this fabric was 3.79, the packing density of the fabric was 0.49, and the twist coefficient × fabric packing density was 1.85. The treatment of the fabric was carried out in the same manner as in Example 1 to produce a flame-retardant spun yarn No. 20 / monofilament according to the present invention. The fibrillation property of the obtained recycled fiber, the ratio of fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0056] [Comparative Example 3] As a textile product for recycling to be recycled, a flame-retardant work clothing fabric composed of 95% by weight of meta-aramid fiber and 5% by weight of para-aramid fiber for work clothing was used. Such a fabric is composed of a flame-retardant spun yarn No. 35 / two-filament composed of 95% by weight of polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark) manufactured by Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fiber ("Technora" (trademark) manufactured by Teijin Limited), and the number of twists in the upper direction was 23.6 turns / inch (S twist). The fabric weave is plain weave, and the fabric has a warp density of 65 threads / inch and a weft density of 55 threads / inch. Each parameter required for the fabric packing density was e = 2, i = 2, d = 0.0177. The twist coefficient of the two-filament of this fabric was 5.63, the packing density of the fabric was 0.84, and the twist coefficient × fabric packing density was 4.70. The treatment of the fabric was carried out in the same manner as in Example 1, but fibrillation hardly occurred and it could not be put in as recycled fiber.

[0057] [Comparative Example 4] As a textile product for recycling, a flame-retardant work clothing fabric was used, which consisted of 95% by weight of meta-aramid fiber for work clothing and 5% of para-aramid fiber. Such a fabric was made of a 35-count / 2-ply flame-retardant spun yarn consisting of 95% by weight of polymetaphenylene isophthalamide fiber ("Teijin Conex" (trademark) manufactured by Teijin Limited) and 5% of coparam-phenylene-3,4'-oxydiphenylene terephthalamide fiber ("Technora" (trademark) manufactured by Teijin Limited), and the number of twists per inch in the S twist direction was 25.8 turns / inch. The fabric weave was twill weave (2 / 1), with a warp density of 95 ends / inch and a weft density of 54 picks / inch. Each parameter required for the fabric packing density was e = 3, i = 2, and d = 0.0177. The twist coefficient of the 2-ply yarn of this fabric was 6.17, the packing degree of the fabric was 0.83, and the twist coefficient × fabric packing density was 5.09. The treatment of the fabric was carried out in the same manner as in Example 1, but almost no fibrillation occurred and it could not be put into use as recycled fiber.

[0058]

Table 1

Industrial Applicability

[0059] According to the present invention, there are provided a method for manufacturing recycled spun yarn that enables efficient and sufficient fibrillation during recycling, and a fiber product containing the spun yarn, and its industrial value is extremely high.

Claims

1. A method for manufacturing recycled spun yarn, comprising: using a flame-retardant spun yarn-containing fabric that satisfies the following formula (1), or a fiber product using the fabric, applying an oil agent before or after cutting to obtain a cut product, and manufacturing a spun yarn using the flame-retardant recycled fiber obtained by opening the cut product. Twist factor × Fabric packing density ≤ 4.5... (1) Twist factor × Fabric packing density ≤ 4.5... (1)

2. The method for manufacturing recycled spun yarn according to Claim 1, wherein the oil agent contains an alkyl phosphate metal salt.

3. The method for manufacturing recycled spun yarn according to Claim 1, wherein the oil agent contains a silicone-based component.

4. The method for manufacturing recycled spun yarn according to Claim 1, wherein the adhesion amount of the oil agent is 0.2 to 1.0% by weight based on the weight of the flame-retardant recycled fiber.

5. The method for manufacturing recycled spun yarn according to Claim 1, wherein the flame-retardant recycled fiber is mixed at a ratio of 10 to 90% by weight of the total spun yarn before or during spinning.

6. The method for manufacturing recycled spun yarn according to Claim 1, wherein the flame-retardant recycled fiber contains 10% by weight or more of short fibers having a length of 20 mm or more, based on the weight of the spun yarn.

7. The method for manufacturing recycled spun yarn according to Claim 1, wherein the flame-retardant recycled fiber contains 10% by weight or more of short fibers having a length of 40% or more of the short fiber length used in the fabric, based on the weight of the spun yarn.

8. A fiber product containing the spun yarn obtained by the manufacturing method according to any one of Claims 1 to 7.

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