Flame-retardant spun yarn and method for producing same

Abstract

The purpose of the present invention is to provide: a flame-retardant spun yarn which has excellent flame retardancy, water absorption properties and heat-retaining properties, has a cotton-like tactile sensation when brought into contact with the skin, and can be uniformly dyed; and a method for easily producing the flame-retardant spun yarn.　The present invention provides a flame-retardant spun yarn having a core-sheath structure, the flame-retardant spun yarn being characterized in that: a core in the core-sheath structure is formed from modacrylic fibers; and a sheath in the core-sheath structure is formed from cotton fibers.

Description

Flame-retardant spun yarn and its manufacturing method

[0001] The present invention relates to a flame-retardant spun yarn and a method for producing the same.

[0002] BACKGROUND ART Conventionally, flame-retardant clothing has been required as clothing to be worn when performing work that may involve contact with fire.

[0003] Fabrics for manufacturing such garments have been proposed (see, for example, Patent Document 1). In Patent Document 1, flame-retardant fibers are used as spun yarns for manufacturing the fabric (see claim 1 of Patent Document 1).

[0004] However, the flame-retardant fiber described in Patent Document 1 has a problem in that it is made of a resin that exhibits flame retardancy, and therefore has a poor texture, and when used in clothing, it causes an irritating feeling when it comes into contact with the skin.

[0005] Furthermore, spun yarns for producing clothing are required to have water absorbency and heat retention. Patent Document 1 does not consider these properties at all, and there is a problem that spun yarns exhibiting these properties cannot be obtained.

[0006] Furthermore, spun yarns are often dyed, and need to be dyed uniformly. In Patent Document 1, a flame-retardant resin is used to impart flame retardancy, which causes the problem of being unable to dye uniformly.

[0007] Therefore, there is a need for the development of a flame-retardant spun yarn that has excellent flame retardancy, water absorbency, and heat retention, feels like cotton when it comes into contact with the skin, and can be dyed uniformly, as well as a manufacturing method that can easily produce such flame-retardant spun yarn.

[0008] JP 2014-240532 A

[0009] The present invention aims to provide a flame-retardant spun yarn that is excellent in flame retardancy, water absorbency, and heat retention, has a cotton-like feel when in contact with the skin, and can be uniformly dyed, and a manufacturing method for easily manufacturing the flame-retardant spun yarn.

[0010] As a result of extensive research, the inventors discovered that the above-mentioned object can be achieved by using a flame-retardant spun yarn having a core-sheath structure in which the core is formed from modacrylic fiber and the sheath is formed from cotton fiber, and thus completed the present invention.

[0011] That is, the present invention relates to the following flame-retardant spun yarn and a method for producing the same: 1. A flame-retardant spun yarn having a sheath-core structure, wherein the core of the sheath-core structure is formed of modacrylic fiber, and the sheath of the sheath-core structure is formed of cotton fiber. 2. The flame-retardant spun yarn according to item 1, wherein the modacrylic fiber content is 50 to 70% by mass, with the flame-retardant spun yarn being 100% by mass. 3. The flame-retardant spun yarn according to item 1 or 2, wherein the coverage of the core in the sheath-core structure is 70% or more. 4. Item 4. A method for producing a flame-retardant spun yarn, comprising: (1) step 1 of mixing modacrylic fiber and cotton fiber to prepare a striper; and (2) step 2 of twisting the striper, wherein the flame-retardant spun yarn has a core-sheath structure, the core of the core-sheath structure being formed from modacrylic fiber, and the sheath of the core-sheath structure being formed from cotton fiber. 5. A method for producing a flame-retardant spun yarn, comprising: a drawing step after step 1; 6. A method for producing a flame-retardant spun yarn, comprising: a roving step after the drawing step;

[0012] The flame-retardant spun yarn of the present invention has excellent flame retardancy, water absorbency, and heat retention, feels like cotton when in contact with the skin, and can be dyed uniformly. Furthermore, the production method of the present invention makes it easy to produce the flame-retardant spun yarn.

[0013] 1 is a photograph of the flame-retardant spun yarn obtained in Example 1. FIG. 2 is a photograph of the flame-retardant spun yarn obtained in Example 1.

[0014] The flame-retardant spun yarn and the method for producing the same of the present invention will be described in detail below.

[0015] 1. Flame-retardant spun yarn The flame-retardant spun yarn of the present invention has a sheath-core structure, in which the core of the sheath-core structure is formed from modacrylic fiber and the sheath of the sheath-core structure is formed from cotton fiber. The flame-retardant spun yarn of the present invention exhibits excellent flame retardancy because the core of the sheath-core structure is formed from modacrylic fiber. Furthermore, the flame-retardant spun yarn of the present invention has excellent water absorbency and heat retention because the sheath of the core-sheath structure is formed from cotton fiber. Furthermore, the flame-retardant spun yarn of the present invention has an excellent texture because the core is formed from modacrylic fiber and the sheath is formed from cotton fiber. When worn as clothing, the irritation caused by the modacrylic fiber is reduced, the texture when in contact with the skin feels like cotton, and the yarn can be uniformly dyed. In other words, the flame-retardant spun yarn of the present invention has all the properties of excellent flame retardancy, water absorbency, and heat retention, feels like cotton when it comes into contact with the skin, and can be dyed uniformly.

[0016] The flame-retardant spun yarn of the present invention has a core-sheath structure. The core-sheath structure is not particularly limited as long as it has a core covered by a sheath. An example of such a core-sheath structure is a flame-retardant spun yarn in which the modacrylic fiber forms the core and the cotton fiber forms the sheath so as to surround the core, as shown in Figures 1 and 2. More specifically, in a cross section perpendicular to the longitudinal direction of the flame-retardant spun yarn, the structure has a central circle formed by the modacrylic fiber and a circumscribed circle formed by the cotton fiber located outside the central circle.

[0017] In the flame-retardant spun yarn of the present invention, the coverage of the core in the sheath-core structure is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. When the lower limit of the coverage is within the above range, the water absorbency and heat retention of the flame-retardant spun yarn are further improved, the cotton-like feel when in contact with the skin is further improved, and more uniform dyeing is possible. The higher the upper limit of the coverage, the better, and it may be 100%, 99%, or 95%.

[0018] (Core) In the flame-retardant spun yarn of the present invention, the core is formed of a modacrylic fiber, which is a fiber made of a copolymer of acrylonitrile and a monomer copolymerizable therewith.

[0019] The modacrylic fiber is preferably a fiber made of a resin containing 35% by mass or more but less than 85% by mass of an acrylonitrile component. The monomer copolymerizable with acrylonitrile is usually a halogen compound such as vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, or 2,3-dibromoacrylate.

[0020] The modacrylic fiber preferably contains a flame retardant, such as an inorganic flame retardant, a halogen-based flame retardant, or a phosphorus-based flame retardant, in order to further improve the flame retardancy of the flame-retardant spun yarn of the present invention.

[0021] Examples of the inorganic flame retardant include antimony oxides such as antimony pentoxide, antimony tetroxide, and antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, sodium borate, molybdenum oxide, red phosphorus, tin oxide, zirconium hydroxide, and barium metaborate, and among these, antimony oxide is more preferred.

[0022] Examples of the halogen-based flame retardant include decabromodiphenyl oxide, octabromodiphenyl oxide, hexabromocyclododecane, bis(tribromophenoxy)ethane, ethylenebistetrabromophthalimide, hexabromobenzene, polydibromophenylene oxide, tetrabromobisphenol A, tetrabromobisphenol S, tris(2,3-dibromopropyl-1)isocyanate, tribromophenol allyl ether, brominated polystyrene, tribromoneopentyl alcohol, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyethoxy-3,5-dibromophenyl)propane, chlorinated paraffin, chlorinated polyethylene, and perchlorocyclopentadecanone.

[0023] Examples of the phosphorus-based flame retardant include triethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, resorcinol-bis-(diphenyl phosphate), 2-ethylhexyl diphenyl phosphate, dimethyl methyl phosphate, triallyl phosphate, trichloroethyl phosphate, tris-dichloropropyl phosphate, tris-β-chloroethyl phosphate, tris-β-chloropropyl phosphate, tris(tribromophenyl)phosphate, tris(dibromophenyl)phosphate, tris(tribromoneopentyl)phosphate, diethyl-N,N-bis(2-hydroxyethyl)aminomethyl phosphate, ammonium phosphate, ammonium polyphosphate, and polychlorophosphites.

[0024] The content of the flame retardant in the modacrylic fiber is preferably 10 to 30 parts by mass, based on 100 parts by mass of the modacrylic resin. By setting the lower limit of the flame retardant content within the above range, the flame retardancy of the flame-retardant spun yarn is further improved. By setting the upper limit of the flame retardant content within the above range, the production of the flame-retardant spun yarn is made easier.

[0025] In the flame-retardant spun yarn of the present invention, the content of the modacrylic fiber is preferably 40 to 70% by mass, more preferably 50 to 70% by mass, even more preferably 50 to 67% by mass, and particularly preferably 53 to 60% by mass, based on 100% by mass of the flame-retardant spun yarn. When the lower limit of the modacrylic fiber content is within the above range, the flame retardancy of the flame-retardant spun yarn is further improved. When the upper limit of the modacrylic fiber content is within the above range, production of the flame-retardant spun yarn is made easier.

[0026] (Sheath) In the flame-retardant spun yarn of the present invention, the sheath is formed from cotton fibers. As the cotton fibers, natural cotton fibers or ripped cotton fibers can be used.

[0027] The above-mentioned recovered fibers are cotton fibers obtained by subjecting cotton yarn or cotton knitted or woven fabric to a recovered machine for loosening. Examples of recovering machines that can be used include a lug machine, knot breaker, garnet machine, and cutter. These recovered machines can be selected as desired depending on the thickness of the cotton fibers that make up the cotton yarn or knitted or woven fabric, the degree of twist between the fibers, and the shape of the yarn or knitted or woven fabric. Several recovered machines of the same or different types can also be connected in series for use.

[0028] In the flame-retardant spun yarn of the present invention, the cotton fiber content is preferably 30 to 60% by mass, more preferably 33 to 50% by mass, and even more preferably 40 to 47% by mass, based on 100% by mass of the flame-retardant spun yarn. When the lower limit of the cotton fiber content is within the above range, the production of the flame-retardant spun yarn becomes easier. When the upper limit of the cotton fiber content is within the above range, the flame retardancy of the flame-retardant spun yarn is further improved.

[0029] 2. Manufacturing Method of Flame-Retardant Spun Yarn The manufacturing method of the flame-retardant spun yarn of the present invention comprises (1) Step 1 of mixing modacrylic fiber and cotton fiber to prepare a striper, and (2) Step 2 of twisting the striper, wherein the flame-retardant spun yarn has a core-sheath structure, the core of the core-sheath structure being formed from modacrylic fiber, and the sheath of the core-sheath structure being formed from cotton fiber. Each step of the manufacturing method will be explained below.

[0030] (Step 1) Step 1 is a step of preparing a striper by mixing modacrylic fibers and cotton fibers. In step 1, the striper is obtained by aligning modacrylic fibers and cotton fibers in parallel and processing them into a bundle.

[0031] The processing method is not particularly limited as long as it can align modacrylic fibers and cotton fibers in parallel and process them into bundles. Examples of such processing methods include carding, aligning the extracted fibers in parallel on a plane, and processing them into threads.

[0032] Carding is a process to remove impurities and align the modacrylic and cotton fibers in a certain direction. After these fiber bundles are mixed and beaten separately, the resulting sheet-like (wrapped) fibers are combed and extracted. The extracted fibers are then aligned on a flat surface and processed into threads to prepare stripers.

[0033] In the upper carding, the method of aligning the extracted fibers in a plane is preferably to arrange the modacrylic fibers on the inside and the cotton fibers on the outside. In this case, the number of modacrylic fibers on the inside is preferably 2 to 8, more preferably 3 to 6, and even more preferably 4. The number of cotton fibers on the outside is preferably 1 to 4, more preferably 2 to 3, and even more preferably 2, on each side of the modacrylic fibers.

[0034] In the method for preparing the flame-retardant spun yarn of the present invention, first, modacrylic fibers alone are arranged parallel on a plane in the carding process to prepare a striper made of modacrylic fibers. Also, cotton fibers alone are arranged parallel on a plane to prepare a striper made of cotton fibers. The modacrylic fiber striper and the cotton fiber striper are then aligned again in a draw frame to obtain a striper having a modacrylic staple fiber core and a cotton fiber sheath. Furthermore, a preferred method is to prepare a sheath-core roving in a roving process using a sheath-core striper, and then stretch and twist the sheath-core roving in a spinning frame to prepare a sheath-core spun yarn.

[0035] The processing method for aligning the extracted fibers on a plane and processing them into a thread is not particularly limited, and an example is a method in which multiple fibers aligned on a plane are passed through a tapered nozzle to narrow them from both sides to prepare a single striper.

[0036] In step 1 described above, modacrylic fiber and cotton fiber are mixed to prepare a striper.

[0037] (Drawing Step) In the production method of the present invention, a drawing step may be carried out after the step 1 described above.

[0038] In the present invention, the drawing step is a step of drawing the striper prepared in step 1 to obtain a uniform and long striper.

[0039] The method for drawing is not particularly limited, and for example, a method of drawing by front draft using a drawing frame can be mentioned.

[0040] (Roving Step) The production method of the present invention may have a roving step after the drawing step.

[0041] In the present invention, the drawing step is a step of further drawing the striper that has been subjected to the drawing step.

[0042] The method for roving is not particularly limited, and for example, a method using a roving frame and stretching the fibers with the draft rollers of the roving frame to form a roving yarn can be mentioned.

[0043] (Step 2) Step 2 is a step of twisting the striper prepared in step 1. In the production method of the present invention, by twisting the striper prepared in step 1, a flame-retardant spun yarn having a core-sheath structure, in which the core is formed of modacrylic fiber and the sheath is formed of cotton fiber, can be produced.

[0044] The method for twisting the striper is not particularly limited, and the twist can be applied by a conventionally known method, such as twisting by a spinning machine.

[0045] In step 2 described above, the striper prepared in step 1 is twisted to produce the flame-retardant spun yarn of the present invention.

[0046] The above-described production method makes it possible to easily produce the flame-retardant spun yarn of the present invention, which has a core-sheath structure with the core made of modacrylic fiber and the sheath made of cotton fiber. Such flame-retardant spun yarn of the present invention has excellent flame retardancy, water absorbency, and heat retention, is less irritating to the skin when it comes into contact with the skin, and can be dyed uniformly, making it useful for a variety of applications.

[0047] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0048] The raw materials used in the examples are as follows:

[0049] Modacrylic fiber: manufactured by Kaneka Corporation, trade name Protex Q, single fiber fineness 1.7 dtex, fiber length 38 mm Cotton fiber: cotton originating from the United States was used.

[0050] Example 1 (Step 1) The above-mentioned modacrylic fiber and cotton fiber were prepared. Four modacrylic fibers were arranged in parallel, and two cotton fibers were arranged in parallel on each of the four modacrylic fibers, for a total of eight fibers mixed together. Next, a striper was prepared using the mixed fibers in a drawing frame (manufactured by Toyota Industries Corporation) under conditions of 8x draft.

[0051] (Roving Step) The striper prepared in step 1 was stretched and spun by a roving frame (manufactured by Toyota Industries Corporation) to prepare a roving yarn.

[0052] (Step 2) The roving yarn that had been subjected to the above-mentioned roving step was used to produce a spun yarn in a spinning machine (manufactured by Toyota Industries Corporation) under the conditions of British cotton count 30 and Z twist. The content of modacrylic fiber in the spun yarn is shown in Table 1.

[0053] Examples 2 and 3, Comparative Examples 2 and 3 The composition of the flame-retardant spun yarn, the modacrylic fiber content, and the core covering rate were changed as shown in Table 1. Otherwise, the spun yarn was produced in the same manner as in Example 1.

[0054] Comparative Example 1 Four modacrylic staple fiber stripers and four cotton fiber stripers were alternately arranged to prepare a blended striper on a drawing machine. Then, in the same manner as in Example 1, a blended yarn of 30 British count was produced.

[0055] (Evaluation Method) The following evaluations were carried out for the Examples and Comparative Examples.

[0056] Core Coverage Ratio (Coverage Ratio) Using standard hand-spun yarn, a 28-gauge jersey weave was spun on a circular knitting machine and then subjected to a scouring and bleaching process to prepare a knitted fabric. The knitted fabric was then immersed in a black reactive dye at 95°C for 10 minutes to dye it black and prepare a test piece. The color depth (K / S) of the dyed spun yarn (test piece) was measured using a colorimeter (CCM). Separately, a 100% cotton knitted fabric of the same count was subjected to the same scouring, bleaching, and dyeing process as above, and the color depth (K / S) of the 100% cotton knitted fabric after dyeing was measured using a colorimeter (CCM). The core coverage ratio (coverage ratio) was calculated from the obtained measurements using the following formula: (Core Coverage Ratio) (%) = [(Color depth (K / S) of test piece) / (Color depth (K / S) of 100% cotton knitted fabric)] x 100

[0057] Flame retardancy The flame retardancy of the spun yarn was measured using Method A (surface ignition) of ISO 15025 (JIS T 8022). Evaluation was based on the following evaluation criteria. A rating of △ or higher is considered acceptable for practical use. ◎: Afterflame time 0 seconds ○: Afterflame time more than 0 seconds but less than 1 second △: Afterflame time 1 second or more but less than 2 seconds ×: Afterflame time more than 2 seconds

[0058] Water Absorbency Knitted fabrics were produced using the spun yarns, and the water absorbency of the knitted fabrics was measured according to the Byreck method of JIS L 1907.

[0059] Heat retention: Knitted fabrics were prepared using the spun yarns to prepare test pieces, and the heat retention of the test pieces was measured using a KES Thermo Lab II tester according to the following method.

[0060] (Method of measuring heat retention) A test piece was attached to the constant temperature heating element (ambient temperature +10°C) of a heat retention tester, and a constant speed of air (30cm / sec or 1m / sec) was blown onto the surface of the test piece. The amount of heat loss (A) through the test piece at this time was measured. Next, the same temperature difference and heat loss dissipated per unit time (B) were measured without the test piece in a bare state. The heat retention rate was calculated based on the following formula: (Heat retention rate (%)) = [1 - ((A) Heat dissipation when the test piece is attached to the heating element (J / cm 2 s) / (B) Heat dissipation from the naked heating element (J / cm 2 ・s)) × 100

[0061] Dyeing uniformity The dyeing uniformity of the spun yarn was visually observed and evaluated according to the following evaluation criteria. A rating of △ or higher is considered to be acceptable for practical use. ◎: No unevenness ○: Small unevenness (3 cm or less) is present, but the number is small (1 m ２ 5 or less hits) △: Small unevenness (3 cm or less), 1 m ２ More than 5 hits ×: Many uneven spots (more than 3 cm)

[0062] The results are shown in Table 1.

[0063]

[0064] In Examples 1 to 3, the core coverage (coverage) was high at 83%, 76%, and 51%, respectively, and the feel when in contact with the skin was like cotton. It was found that the higher the core coverage (coverage), the more the core formed from modacrylic fiber was covered by the sheath formed by twisting cotton fiber, and the more cotton-like the feel when in contact with the skin was improved.

Claims

1. A flame-retardant spun yarn having a core-sheath structure, wherein the core of the core-sheath structure is formed from modacrylic fiber, and the sheath of the core-sheath structure is formed from cotton fiber.

2. The flame-retardant spun yarn according to claim 1, wherein the content of the modacrylic fiber is 50 to 70 mass % based on 100 mass % of the flame-retardant spun yarn.

3. The flame-retardant spun yarn according to claim 1, wherein the coverage of the core in the core-sheath structure is 70% or more.

4. A method for producing flame-retardant spun yarn, comprising: (1) step 1 of mixing modacrylic fiber and cotton fiber to prepare a striper; and (2) step 2 of twisting the striper, wherein the flame-retardant spun yarn has a core-sheath structure, the core of the core-sheath structure is formed from modacrylic fiber, and the sheath of the core-sheath structure is formed from cotton fiber.

5. The method according to claim 4, further comprising a drawing step after step 1.

6. The method according to claim 5, further comprising a roving step after the drawing step.