Flame-retardant spun yarn fabric, method for producing spun yarn from the flame-retardant spun yarn fabric, and textile products

Abstract

To provide a flame-retardant spun yarn woven fabric which contains a flame-retardant spun yarn and can be efficiently and sufficiently opened when recycled, a method for producing a spun yarn from the flame-retardant spun yarn woven fabric, and a textile product containing the spun yarn obtained by the method.SOLUTION: In a flame-retardant woven fabric containing a flame-retardant spun yarn, the product of a twist coefficient and a woven fabric packing density is 4.5 or less so as to be suitable for recycling. If necessary, the flame-retardant spun yarn obtained from the flame-retardant spun yarn woven fabric is formed into a textile product.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a flame-retardant spun yarn fabric containing flame-retardant spun yarns, suitable for recycling, a method for producing spun yarns by recycling the flame-retardant spun yarn fabric, and a fiber product containing the spun yarns obtained by the production method.

Background Art

[0002] Conventionally, since flame-retardant fibers are excellent in heat resistance and flame resistance, after being made into flame-retardant fabrics, they are used for work clothes for work where there is a risk of exposure to flames, such as in fire departments, power companies, chemical companies, etc. Flame-retardant fabrics use flame-retardant fibers such as wholly aromatic polyamide fibers, but their performance deteriorates with use, and they become unusable due to dirt, abrasion, tearing, fraying, etc., and are ultimately discarded. Also, cutting scraps are generated in each stage of manufacturing flame-retardant fabrics and when sewing work clothes using flame-retardant fabrics, and a large amount of scraps generated in these respective processes and used products are produced as waste. Such process scraps and used products are hardly recycled, unlike products made of general-purpose fibers (such as polyester fibers and cotton), and most of them are incinerated or landfilled.

[0003] On the other hand, in recent years, in order to suppress resource consumption and reduce the environmental load, the formation of a recycling-oriented society is demanded. Specifically, for used products of general-purpose fibers, recycling has been carried out for what has been conventionally called waste fibers such as rags and waste fibers from old clothes. For example, in the recycled market, 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] It is also conceivable to apply the same recycling method as for general-purpose fiber products to the process scraps and used products of flame-retardant fabrics. However, since flame-retardant fibers are superior in heat resistance and flame resistance to general-purpose fibers, and also have high tensile strength and cut resistance, when using a normal fiber opener under the same conditions as for general-purpose fiber products, problems occur, and efficient and sufficient fiber opening and recycling cannot be carried out. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-233409 [Patent Document 2] Japanese Patent Publication No. 2005-105491 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a flame-retardant spun yarn fabric that allows for efficient and sufficient fiber opening during recycling, a method for producing spun yarn from the flame-retardant spun yarn fabric, and a textile product containing the spun yarn obtained by the production method. [Means for solving the problem]

[0007] The inventors, after diligent study to achieve the above objectives, have completed the present invention. Thus, the following invention is provided.

[0008] 1. A flame-retardant spun yarn fabric that contains flame-retardant spun yarn and satisfies the following formula (1). Twist coefficient × Fabric filling density ≤ 4.5 (1) 2. The flame-retardant spun yarn fabric described in item 1 above, wherein the flame-retardant spun yarn is blended with flame-retardant fibers having a limiting oxygen index of 25 or higher as measured by JIS L1091 Method E in an amount of 40% by weight or more relative to the weight of the spun yarn. 3. A method for producing spun yarn, comprising producing spun yarn using flame-retardant recycled fibers obtained by opening the flame-retardant spun yarn fabric described in 1 or 2 above, or a textile product using said fabric. 4. The method for producing spun yarn according to item 3 above, wherein the flame-retardant recycled fibers are mixed in at a ratio of 10 to 90% by weight of the total spun yarn before spinning or during spinning. 5. A method for producing spun yarn as described in 3 or 4 above, wherein unused flame-retardant fibers with a fiber length of 30 to 200 mm and a limiting oxygen index of 25 or higher as measured by JIS L1091 Method E are mixed in a proportion of 10 to 90% by weight of the total spun yarn before spinning or during spinning. 6. A method for producing spun yarn according to any one of 3 to 5 above, wherein conductive fibers are mixed in at a ratio of 0.1 to 5% by weight of the total spun yarn before spinning or during spinning. 7. A method for producing spun yarn according to 5 or 6 above, wherein the flame-retardant recycled fiber and / or unused flame-retardant fiber is one or more fibers selected from the group consisting of meta-aramid fiber, para-aramid fiber, polypara-phenylene benzoxazole fiber, polybenzimidazole fiber, polybenzimidazole fiber, polyimide fiber, polyetherimide fiber, polyamideimide fiber, carbon fiber, polyphenylene sulfide fiber, polyvinyl chloride fiber, flame-retardant rayon, modacrylic fiber, flame-retardant acrylic fiber, flame-retardant polyester fiber, flame-retardant vinylon fiber, melamine fiber, fluorine fiber, flame-retardant wool, and flame-retardant cotton. 8. A method for producing spun yarn according to any one of the above 3 to 7, wherein the twist coefficient of the obtained spun yarn is 2.5 to 6.0. 9. A textile product containing spun yarn obtained by any of the manufacturing methods described in 3 to 8 above. [Effects of the Invention]

[0009] Flame-retardant spun yarn fabrics become unusable due to soiling, tearing, or damage during use. However, even in discarded products or waste generated during manufacturing, their properties do not disappear. According to the flame-retardant spun yarn fabric of the present invention, flame-retardant recycled fibers can be easily obtained by, for example, washing, applying oil, crushing, and opening using a conventional fiber opening machine. Furthermore, by mixing in an appropriate amount of unused short fibers, the performance can be easily restored to a level suitable for the required application. As a result, it can contribute to environmental protection in a circular economy.

[0010] Furthermore, in the recycling method according to the present invention, it is preferable to form the spun yarn while maintaining the length of the short fibers in a state close to the length of the original spun yarn. In addition, unused short fibers may be mixed in if desired. As a result, the flame-retardant recycled spun yarn according to the present invention has the advantage of high recovery of tensile strength. This increases the added value of the flame-retardant recycled spun yarn, broadens its applications, and the expansion of applications leads to an expansion of the spun yarn, thereby absorbing the recycling costs. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. The flame-retardant spun yarn fabric suitable for recycling according to the present invention is expressed by the following formula (1), which is determined by the twist coefficient calculated from the number of twists and yarn count of the spun yarn constituting the fabric, the fabric structure of the fabric, and the fabric filling density calculated from the yarn count, etc. Twist coefficient × Fabric filling density ≤ 4.5 (1)

[0012] Here, the twist coefficient can be calculated using the formula 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. From the viewpoint of the physical properties and flexibility of the fabric, the twist coefficient K is preferably in the range of 2.5 to 6.0. In particular, it is preferably 2.5 to 4.5 for single yarns and 3.0 to 6.0 for double yarns. 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 single yarn fabrics (fabrics made from single spun yarns), the twist coefficient is obtained from the number of undertwists of the single yarn, and in the case of double yarn fabrics (fabrics made from double spun yarns), the twist coefficient is obtained from the number of overtwists of the double yarn.

[0013] Furthermore, the fabric filling density can be determined as follows. T = (ta1 + ta2) / (tm1 + tm2) Here, T is the density of the fabric, ta1 is the amount of yarn actually occupied within a complete structure in the warp direction, and is the warp density (threads / cm) per cm. Similarly, ta2 is the amount of yarn actually occupied within a complete structure in the weft direction, and is the transverse density (threads / cm) per cm. tm1 is the theoretical maximum amount of yarn occupied within a complete structure in the warp direction, and tm2 is the theoretical maximum amount of yarn occupied within a complete structure in the weft direction. tm can be expressed by the following equation. tm = e / ((ei) × 3.14 × d / 4 + 2id)

[0014] Here, e is the number of threads in the warp direction (weft direction in the case of tm2) for tm1, and i is the number of intersections in the warp direction (weft direction in the case of tm2) for tm1. Table 2 shows examples of e and i for various complete weaves (plain weave, 1 / 2 twill weave, 2 / 2 twill weave, 3 / 1 twill weave, 3 / 3 twill weave, 4 / 4 twill weave, 5-ply 2-ply satin). Needless to say, the present invention is not limited to these weaves. Note that in the various complete weaves listed in Table 2, e and i have the same value in the warp and weft directions. In the present invention, it is preferable that e and i have the same value in the warp and weft directions, but they may be different.

[0015] Furthermore, d is the diameter of the thread and can be expressed by the following equation. d(cm)=0.00357×√((tex / (φ×ρf)) Here, tex is the value obtained by converting the spun yarn count to tex, φ is the yarn packing density, and ρf is the specific gravity of the fiber. For simplicity, the yarn packing density φ is calculated as 1 in this application.

[0016] When the twist count of spun yarn is high, it can become difficult to open the fibers during the unraveling and re-fluffing processes. Similarly, if the fabric filling density is too high, it may become difficult to open the fibers during the unraveling and re-fluffing processes. When the product of the twist coefficient and the fabric filling density is 4.5 or less, opening the fibers during the unraveling and re-fluffing processes becomes easier.

[0017] In addition, the flame-retardant spun yarn fabric of the present invention is a fabric containing flame-retardant spun yarns, and the flame-retardant spun yarns contain flame-retardant fibers. Here, the flame-retardant fibers are flame-retardant fibers having a limiting oxygen index of 25 or more measured by the JIS L1091-1999 E method. Examples of such flame-retardant fibers include meta-aramid fibers, para-aramid fibers, poly(paraphenylene 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, and the like. One or more of these flame-retardant fibers can be used.

[0018] Among them, from the viewpoint of exhibiting 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.), and coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (commercially available products include "Technora" (trademark name) manufactured by Teijin Limited, etc.).

[0019] These flame-retardant fibers may contain additives such as antioxidants, ultraviolet absorbers, heat stabilizers, flame retardants, titanium oxide, colorants, and inert fine particles within a range not impairing the object of the present invention.

[0020] The flame-retardant spun yarn preferably consists only of the above-mentioned flame-retardant fibers, but may contain non-flame-retardant fibers (fibers with a limiting oxygen index of less than 25 measured by the E method of JIS L1091-1999). In this case, the content of the flame-retardant fibers is preferably blended at 40% by weight or more of the whole spun yarn. At that time, examples of the non-flame-retardant fibers include polyester fibers, nylon fibers, rayon fibers, polynosic fibers, lyocell fibers, acrylic fibers, vinylon fibers, cotton, hemp, wool, etc. One or more of these non-flame-retardant fibers can be used.

[0021] 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.

[0022] Since the flame-retardant spun yarn fabric of the present invention has the above-mentioned configuration, efficient and sufficient fiber opening is possible when recycling. Note that the flame-retardant spun yarn fabric of the present invention may be not only unused flame-retardant spun yarn fabric, but also used flame-retardant spun yarn fabric, process scraps generated during the production of the fabric, sewing scraps generated during sewing, and the like.

[0023] Next, the method for manufacturing the spun yarn of the present invention is characterized by recycling (recycling) the spun yarn using the flame-retardant recycled fiber (sometimes simply referred to as "recycled fiber") obtained from the above-mentioned flame-retardant spun yarn fabric or a fiber product using the fabric (hereinafter sometimes collectively referred to as "flame-retardant spun yarn product").

[0024] At that time, the flame-retardant spun yarn fabric and the fiber product using the fabric may be washed in advance as desired, then an oil agent may be applied as desired, followed by a crushing treatment, the obtained crushed material may be opened into a cotton-like material, and such a cotton-like material may be spun to regenerate the spun yarn.

[0025] Here, the textile product is not particularly limited as long as it includes the flame-retardant spun yarn fabric. Specifically, examples include flame-retardant work clothes, fire suits, work gloves, and safety industrial materials (such as textiles) that contain flame-retardant spun yarn. In such flame-retardant spun yarn products, it is preferable that the flame-retardant spun yarn is used alone. However, it may also contain yarn other than flame-retardant spun yarn (preferably spun yarn). In this case, it is preferable that the content of the flame-retardant spun yarn is 50% by weight or more of the total textile product. In the present invention, the used flame-retardant spun yarn product may include not only used flame-retardant spun yarn products, but also fiber scraps and offcuts generated in the process of manufacturing flame-retardant spun yarn products. The following describes each step in detail.

[0026] First, it is preferable to pre-wash the flame-retardant spun yarn products. This washing process removes dirt, as well as impurities such as plastic and metal powder and oil from the used flame-retardant spun yarn products, thereby reducing the occurrence of equipment problems and enabling efficient recycling. In particular, it is preferable to thoroughly wash work gloves as they may contain metal or plastic fragments or have oil on them. Furthermore, washing is also preferable in terms of improving the quality of recycled products. In addition, it is possible to check whether the flame-retardant spun yarn products used as raw materials can be recycled or not, and to check whether the products contain machine parts such as bolts or various other impurities. The washing method is not particularly limited, and known means may be used.

[0027] In the present invention, depending on the humidity and weather, an oil agent may be applied to the flame-retardant spun yarn product to be recycled raw material before or during the crushing process described later, as necessary. The application of this oil agent is not limited to before or during the crushing process, but may also be applied to the crushed material before or during fiber opening, or to the cotton-like material before or during spinning. By applying the oil agent in this way, the generation of static electricity during the crushing process, fiber opening process, and spinning process can be suppressed, which has the advantage of enabling the aforementioned processes to proceed smoothly. The oil agent is not particularly limited as long as it is an oil agent whose main component is an oil agent that is normally used in spinning. For example, the oil agent may be an oil agent that combines animal or vegetable oil or mineral oil, a lubricant such as an alkyl phosphate potassium salt with a surfactant (anionic surfactant, cationic surfactant, or nonionic surfactant), or an oil agent that further combines these with a high-viscosity polymer substance or colloidal silica. The amount of the oil agent to be applied is not particularly limited, but it is preferably about 2% by weight or less of the weight of the used flame-retardant spun yarn product.

[0028] Next, the flame-retardant spun yarn product is subjected to a crushing process. This crushing process mechanically decomposes and separates the used flame-retardant spun yarn product into yarn, fragments, and cotton-like material, making the fiber opening process easier and promoting cottonization compared to directly opening the product. The crushing process in this invention is not particularly limited as long as the above objective is achieved, and known means may be used. This invention aims to recycle flame-retardant spun yarn product as spun yarn in particular, and the closer the length of the short fibers in the cotton-like material obtained in the subsequent fiber opening process is to the original length, the higher the tensile strength recovery can be recovered in the regenerated spun yarn. Therefore, in the crushing process in this invention, it is preferable to perform a process that increases the proportion of short fibers that are as close to the original length as possible.

[0029] Furthermore, the crushing process may include a cutting process in which the flame-retardant spun yarn product is roughly cut. In this case, depending on the form of the product, it is preferable to lengthen the cutting interval so that the proportion of short fibers that are as close to the original length as possible is increased. For example, the product may be cut at intervals greater than or equal to the length of the short fibers of the spun yarn used in the flame-retardant spun yarn product. It is also preferable to crush the product by biting, tearing, and pulling it out. Furthermore, the process up to the fiber opening process described later may be carried out in a single step by scraping and scraping.

[0030] The conditions for fiber opening vary depending on the shape of the flame-retardant spun yarn product, the type of flame-retardant fiber used in the product, or the type of fiber opening machine. Appropriate conditions can be determined by conducting tests as needed according to the raw material flame-retardant spun yarn product. However, it is preferable to select the fiber opening conditions so that the cotton-like material obtained by the fiber opening process contains 50% by weight or more of short fibers with a length of 20 mm or more. It is also preferable to select the fiber opening conditions so that the material contains 50% by weight or more of short fibers with a length of 40% by weight or more of the short fiber length of the spun yarn used in the original product. As mentioned above, the more short fibers that are long, in other words, have a length close to the original fiber length, the greater the recovery of the tensile strength of the recycled spun yarn (the ratio of the tensile strength of recycled flame-retardant spun yarn to the tensile strength of commercially available spun yarn). The distribution of fiber length can be easily measured by a staple diagram according to "JIS L 1015-2010 8.4.1 Method A". Fiber opening can be performed using known re-drying machines or fiber opening machines.

[0031] Next, the cotton-like material obtained by the above fiber-opening process is spun to regenerate spun yarn. In this invention, before spinning, unused short fibers may be mixed with the cotton-like material obtained by opening the fibers of the unfurled material in a proportion of 90% by weight or less, preferably 10-90% by weight, and more preferably 10-70% by weight. Mixing in unused short fibers has the advantage of more effectively restoring the tensile strength of the regenerated flame-retardant spun yarn. As the unused short fibers, crimped short fibers are preferred. This is because the crimp makes it easier to open strands or tow-shaped fibers. Also, short fibers with a length of 30 mm or more, more preferably 30-200 mm, are preferred. If the length of the unused short fibers is long, the cotton-like material obtained in this invention will be more and longer intertwined, and the binding effect will be enhanced, resulting in a regenerated flame-retardant spun yarn with more restored tensile strength.

[0032] The unused short fibers used in the present invention include (a) commercially available flame-retardant fiber staples, or (b) flame-retardant fiber long fibers or short fibers obtained from fiber scraps and offcuts generated during the manufacturing process of products made from said long fibers. These are preferably about 30 to 200 mm in length and have a crimp that makes them easy to open. The short fibers in (b) can be obtained by cutting fiber scraps and offcuts generated during the manufacturing process of flame-retardant fiber long fibers or products made from said long fibers.

[0033] The method for mixing unused short fibers into a cotton-like material is not particularly limited, and known mixing methods such as a method for blending cotton with polyethylene terephthalate fibers may be used. Furthermore, the mixing of unused short fibers may be performed during spinning, preferably in the cotton blending and beating process. Conductive fibers may also be mixed in before or during spinning at a rate of 0.1 to 5% by weight of the total spun yarn.

[0034] Methods for producing spun yarn from cotton-like material or a mixture of cotton-like material and unused short fibers (hereinafter simply referred to as spinning methods) are well established in the art, and should be followed accordingly. Specific spinning methods include cotton spinning, worsted spinning, woolen spinning, linen spinning, silk spinning, or tow spinning. These methods may also be combined as appropriate. In particular, in the present invention, it is preferable to use cotton spinning, worsted spinning, or woolen spinning methods.

[0035] More specifically, a suitable spinning method described above is one consisting of a blending and beating process, a carding process, a pre-spinning process, and a final spinning process. The following describes each step of the cotton spinning method.

[0036] The carding process is a process in which the cotton-like material, whose bulk density has been reduced by the fiber opening process, is finally separated into individual fibers to produce sliver, which is an aggregate of infinitely long, rod-like fibers. This carding process can be carried out using a known carding machine. In particular, 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 50% by weight or more of short fibers with a length of 20 mm or more, and / or contains 50% by weight or more of short fibers having a length of 40% by weight or more of the short fiber length of the spun yarn used in flame-retardant spun yarn products. The distribution of fiber lengths can be easily measured by a staple diagram in accordance with "JIS L 1015-2010 8.4.1 Method A".

[0037] The pre-spinning process is an intermediate adjustment process that prepares the sliver produced in the carding process for the spinning process by adjusting the fiber arrangement and thickness. This is usually done by using several sets of top and bottom rollers and other equipment to stretch the sliver and arrange the fibers (this is called the drafting process). The pre-spinning process is further divided into the drawing process and the roving process. The drawing process is a drafting operation that mainly focuses on improving the arrangement of sliver with poor fiber arrangement immediately after the carding process, and is usually repeated several times. After that, the roving process is a process in which the thickness of the sliver is gradually reduced to an appropriate thickness. The spinning process is a process in which the roving obtained in the roving process is supplied and finally made to the desired thickness (count), and twisted and wound as desired. Usually, twisting and winding are performed simultaneously in this process.

[0038] In the recycled flame-retardant spun yarn obtained as described above, the twist coefficient of the spun yarn is preferably 2.5 to 6.0. In particular, it is preferably 2.5 to 4.5 when the final yarn is a single yarn and 3.0 to 6.0 when it is a double yarn. It is also preferable that the yarn contains 20% by weight or more of short fibers with a length of 20 mm or more. As mentioned above, the more long short fibers it contains, the greater the recovery of tensile strength. The distribution of fiber length can be easily measured by a staple diagram according to JIS L 1015-2010 8.4.1 Method A.

[0039] Recycled flame-retardant spun yarn containing 20% ​​or more by weight, preferably 35% or more by weight, and more preferably 50% or more of short fibers with a length of 20 mm or more, exhibits the effect of a high ratio of tensile strength of recycled flame-retardant spun yarn to the tensile strength of unused flame-retardant spun yarn, resulting in the advantage of being usable in a wider range of applications. Specifically, the tensile strength of the recycled flame-retardant spun yarn is 15-100%, preferably 35-100%, and more preferably 60-100% of the tensile strength of unused flame-retardant spun yarn. The tensile strength of the spun yarn is measured according to "JIS L 1095:2010 9.5". Furthermore, the recycled flame-retardant spun yarn can be made into a finer yarn and also has advantages such as being softer and having a better texture.

[0040] Here, recycled flame-retardant spun yarn refers to spun yarn obtained by recycling flame-retardant spun yarn products, which are as described above. Furthermore, the fiber length distribution can be easily measured by staple diagram according to "JIS L 1015:2010 8.4.1 Method A".

[0041] The recycled flame-retardant spun yarn according to the present invention contains flame-retardant fibers, and can therefore be applied to various uses that take advantage of the properties of these fibers. For example, the recycled flame-retardant spun yarn can be woven or knitted to produce fabrics. Since such woven fabrics have excellent flame retardancy, they can be used as flame-retardant sheets for various purposes. Furthermore, such fabrics can be used to produce textile products such as clothing. In particular, it is preferable to use the recycled flame-retardant spun yarn according to the present invention for protective clothing applications. Protective clothing applications are not particularly limited as long as the clothing is intended to protect the wearer's body, but examples include flame-retardant work clothes, firefighter suits, and outdoor and sportswear. In addition, the recycled flame-retardant spun yarn of the present invention can be used for weaving, knitting, and other applications, such as protective clothing, gloves, and materials. [Examples]

[0042] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement items in the examples were measured using the methods described below.

[0043] (1) Twist coefficient The twist coefficient was calculated using the formula 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.

[0044] (2) Fabric packing density The fabric filling density was calculated using the following formula. T = (ta1 + ta2) / (tm1 + tm2) Here, T is the density of the fabric, ta1 is the amount of yarn actually occupied within a complete structure in the warp direction, and is the warp density (threads / cm) per cm. Similarly, ta2 is the amount of yarn actually occupied within a complete structure in the weft direction, and is the transverse density (threads / cm) per cm. tm1 is the theoretical maximum amount of yarn occupied within a complete structure in the warp direction, and tm2 is the theoretical maximum amount of yarn occupied within a complete structure in the weft direction. tm was calculated using the following formula. tm = e / ((ei) × 3.14 × d / 4 + 2id) Here, e is the number of warp (or weft) threads in one complete fabric, and i is the number of warp (or weft) intersections in one complete fabric. d is the diameter of the thread and was calculated using 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 yarn packing density, and ρf is the specific gravity of the fiber. For simplicity, the yarn packing density φ was calculated as 1.

[0045] (3) Distribution of fiber length The fiber length distribution was measured using a staple diagram according to JIS L1015-2010 8.4.1 Method A.

[0046] (4) Flame retardant The limiting oxygen index (LOI) was measured according to JIS L1091-1999 Method E (oxygen index method test) and used as an indicator of flame retardancy.

[0047] (5) The ability of recycled fibers to be opened The evaluation was based on four levels: ◎: Excellent, ○: Good, △: Average, ×: Poor.

[0048] (6) Whether or not it can be used in the spinning process The evaluation was done on a two-point scale: ○: Excellent, ×: Inferior.

[0049] [Example 1] For the recycling of flame-retardant spun yarn products, a flame-retardant workwear fabric was used, consisting of 95% by weight of meta-aramid fibers and 5% by weight of para-aramid fibers. This fabric consisted of 40-count / ply flame-retardant spun yarn made of 95% by weight of polymetaphenylene isophthalamide fibers (Teijin Conex (trademark) manufactured by Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Technora (trademark) manufactured by Teijin Limited), with a top twist count of 19.8 turns / inch (S twist). The fabric structure was twill (2 / 2), with a warp density of 86 threads / inch and a weft density of 75 threads / inch. The parameters required for the fabric filling density were e=4, i=2, and d=0.0165. The twist coefficient of this fabric was 4.43, the filling density of the fabric was 0.73, and the twist coefficient × filling density was 3.23. The fabric was cut into approximately 5 cm squares and subjected to washing and drying treatments, and an antistatic oil was applied. After that, the cut flame-retardant fabric was subjected to a crushing treatment, followed by a fiber opening treatment using a re-napping machine. The resulting recycled fibers (including yarn-like material with insufficient fiber opening) had good fiber opening properties. These fibers were mixed with 30% by weight of unused polymetaphenylene isophthalamide fibers (Teijin Limited's "Teijin Conex" (trademark)) with a fineness of 1.7 dtex and a fiber length of 51 mm, and subjected to carding, drawing, and roving processes to produce flame-retardant spun yarn of 20 count / single yarn according to the present invention. The fiber opening properties of the obtained recycled fibers, the percentage of fibers with a fiber length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1. For reference, 100% by weight of unused polymetaphenylene isophthalamide fiber (Teijin Conex, a trademark of Teijin Limited) with a fiber length of 51 mm was used in the carding, drawing, and roving processes to produce a flame-retardant spun yarn of 20 count / single yarn. The properties of the spun yarn are shown in Table 1 for reference.

[0050] [Example 2] For recycling, a flame-retardant workwear fabric was used, consisting of 95% by weight of meta-aramid fibers and 5% by weight of para-aramid fibers. This fabric consisted of 36-count / ply flame-retardant spun yarn made of 95% by weight of polymetaphenylene isophthalamide fibers (Teijin Conex, a trademark of Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Technora, a trademark of Teijin Limited), with a top twist count of 19.8 turns / inch (S twist). The fabric structure was plain weave, with a warp density of 60 threads / inch and a weft density of 49 threads / inch. The parameters required for the fabric filling density were e=2, i=2, and d=0.0174. The twist coefficient of the doubled yarn of this fabric was 4.66, the filling density of the fabric was 0.75, and the twist coefficient × filling density was 3.48. The fabric was treated in the same manner as in Example 1 to produce a flame-retardant spun yarn of 20 count / single yarn according to the present invention. The openability of the obtained recycled fibers, the ratio of fibers with a length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0051] [Example 3] For recycling, a flame-retardant workwear fabric was used, consisting of 95% by weight of meta-aramid fibers and 5% by weight of para-aramid fibers. This fabric consisted of 40-count flame-retardant spun yarn made from 95% by weight of polymetaphenylene isophthalamide fibers (Teijin Conex, a trademark of Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Technora, a trademark of Teijin Limited), with an undertwist count of 24.0 turns / inch (Z twist). The fabric structure was plain weave, with a warp density of 53 threads / inch and a weft density of 53 threads / inch. The parameters required for the fabric filling density were e=2, i=2, and d=0.0117. The twist coefficient of the single yarn of this fabric was 3.79, the filling density of the fabric was 0.49, and the twist coefficient × filling density of the fabric was 1.85. The fabric was treated in the same manner as in Example 1 to produce a flame-retardant spun yarn of 20 count / single yarn according to the present invention. The opening properties of the obtained recycled fibers, the ratio of fibers with a length of 20 mm or more, and the physical properties of the spun yarn are shown in Table 1.

[0052] [Comparative Example 1] For recycling, a flame-retardant workwear fabric was used, consisting of 95% by weight of meta-aramid fibers and 5% by weight of para-aramid fibers. This fabric consisted of 35-count / ply flame-retardant spun yarn made of 95% by weight of polymetaphenylene isophthalamide fibers (Teijin Conex, a trademark of Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Technora, a trademark of Teijin Limited), with a top twist count of 23.6 turns / inch (S twist). The fabric structure was plain weave, with a warp density of 65 threads / inch and a weft density of 55 threads / inch. The parameters required for the fabric filling density were e=2, i=2, and d=0.0177. The twist coefficient of the doubled yarn of this fabric was 5.63, the fabric's filling density was 0.84, and the product of the twist coefficient and fabric filling density was 4.70. The fabric was processed in the same manner as in Example 1, but very little fiber opening occurred, and it could not be used as recycled fiber.

[0053] [Comparative Example 2] For recycling, a flame-retardant workwear fabric was used, consisting of 95% by weight of meta-aramid fibers and 5% by weight of para-aramid fibers. This fabric consisted of 35-count / ply flame-retardant spun yarn made of 95% by weight of polymetaphenylene isophthalamide fibers (Teijin Conex, a trademark of Teijin Limited) and 5% by weight of coparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Technora, a trademark of Teijin Limited), with a top twist count of 25.8 turns / inch (S twist). The fabric structure was a twill weave (2 / 1) with a warp density of 95 threads / inch and a weft density of 54 threads / inch. The parameters required for the fabric filling density were e=3, i=2, and d=0.0177. The twist coefficient of the doubled yarn in this fabric was 6.17, the fabric density was 0.83, and the twist coefficient × fabric density was 5.09. The fabric was processed in the same manner as in Example 1, but the fibers were not opened sufficiently and could not be used as recycled fiber.

[0054] [Table 1-1]

[0055] [Table 1-2]

[0056] [Table 2] [Industrial applicability]

[0057] According to the present invention, a flame-retardant spun yarn fabric is provided, which contains flame-retardant spun yarn and is capable of efficient and sufficient fiber opening when recycled; a method for producing spun yarn from the flame-retardant spun yarn fabric; and a textile product containing the spun yarn obtained by the production method, and its industrial value is extremely high.

Claims

1. A flame-retardant spun yarn fabric comprising flame-retardant fibers made of meta-aramid fibers, characterized in that it satisfies the following formula (1), or a flame-retardant recycled fiber obtained by opening a textile product using the fabric, wherein the flame-retardant fibers made of unused meta-aramid fibers with a fiber length of 30 to 200 mm and a limiting oxygen index of 25 or higher as measured by JIS L1091 E method are mixed in a proportion of 10 to 90% by weight of the total spun yarn before spinning or during spinning, and an oil agent is applied to produce the spun yarn. Twist coefficient × Fabric filling density ≤ 4.5 (1)

2. The method for producing a spun yarn according to claim 1, wherein the flame-retardant spun yarn is blended with the flame-retardant fibers in an amount of 40% by weight or more relative to the weight of the spun yarn.

3. The method for producing spun yarn according to claim 1, wherein the flame-retardant recycled fibers are mixed in at a ratio of 10 to 90% by weight of the total spun yarn before spinning or during spinning.

4. A method for producing spun yarn according to claim 1, wherein conductive fibers are mixed in at a ratio of 0.1 to 5% by weight of the total spun yarn before spinning or during spinning.

5. The method for producing spun yarn according to claim 1, wherein the twist coefficient of the obtained spun yarn is 2.5 to 6.0.

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