Modacrylic fiber and method for producing same

Abstract

Provided are: a modacrylic fiber which has high strength and is capable of exhibiting sufficient performance by itself when applied to a fabric or the like; and a method for producing the modacrylic fiber.　The modacrylic fiber is: a modacrylic fiber wherein the content of a constituent unit derived from acrylonitrile with respect to the mass of a modacrylic resin is not less than 54% by mass but less than 85% by mass, and the dichroic ratio R of 1400-1480 cm-1(-CH2-) in the infrared absorption spectrum is 0.48 or less; or a modacrylic fiber wherein the content of a constituent unit derived from acrylonitrile with respect to the mass of a modacrylic resin is not less than 54% by mass but less than 85% by mass, and the dichroic ratio R of 2220-2260 cm-1(-CN) in the infrared absorption spectrum is 0.40 or less.

Description

Modacrylic fiber and method for producing the same

[0001] This invention relates to modacrylic fibers and a method for producing the same.

[0002] Modacrylic fibers are used in a variety of applications, including clothing, construction, and industrial materials, due to their unique texture, excellent color development, and colorfastness.

[0003] On the other hand, modacrylic fibers are inferior in strength and heat resistance, so to compensate for this, they are sometimes used in combination with other materials that have high strength and high heat resistance when making fabric (see Patent Document 1).

[0004] Special table 2017-501313 publication

[0005] However, while it is possible to impart functionality by mixing modacrylic fibers with other materials, a single material is preferable for recycling, which creates new environmental problems.

[0006] This invention has been made in view of the above problems, and aims to provide a high-strength modacrylic fiber that can exhibit sufficient performance on its own when applied to fabrics, etc., and a method for producing said modacrylic fiber.

[0007] The inventors of the present invention have discovered that when producing modacrylic fibers using a specific modacrylic resin that yields modacrylic fibers, stretching the fibers to a specific total stretch ratio results in the dichromatic ratio R at a specific functional group obtained from the IR spectrum being below a specific value, and as a result, high-strength modacrylic fibers can be obtained, thus completing the present invention.

[0008] Aspects of this disclosure relate to the following modacrylic fibers and methods for producing the same.

[0009] [1] The content of constituent units derived from acrylonitrile relative to the mass of modacryl resin is 54% by mass or more and less than 85% by mass, and the infrared absorption spectrum is 1400-1480 cm⁻¹ －１ [-CH ２[2] Modacrylic fiber having a dichromatic ratio R of 0.48 or less. [2] Modacrylic resin having a content of constituent units derived from acrylonitrile of 54% by mass or more and less than 85% by mass, and an infrared absorption spectrum of 2220 to 2260 cm⁻¹. －１ [1] to [2] Modacrylic fiber having a dichromatic ratio R of [-CN] of 0.40 or less. [3] Modacrylic fiber according to [1] or [2], having a weight-average molecular weight of 100,000 or more and 400,000 or less. [4] Modacrylic fiber according to any one of [1] to [3], having a content of constituent units derived from halogen-containing vinyl monomers relative to the mass of the modacrylic resin of 15% by mass or more and 46% by mass or less. [5] Modacrylic fiber according to any one of [1] to [4], having at least one selected from the group consisting of antimony compounds, compounds containing tin and zinc, and magnesium compounds inside the fiber. [6] Modacrylic fiber according to any one of [1] to [5], having a shrinkage rate of 20% or less at 180°C. [7] Modacrylic fiber according to any one of [1] to [6], having an LOI value of 26 or more. [8] Modacrylic fiber according to any one of [1] to [7], having a tensile strength of 3.2 cN / dtex or more. [9] A fabric containing modacrylic fibers as described in any of [1] to [8].

[10] A method for producing modacrylic fibers, comprising the steps of: wet spinning a spinning stock containing the polymer, wherein the content of constituent units derived from acrylonitrile relative to the mass of the polymer is 54% by mass or more and less than 85% by mass, to obtain an undrawn yarn; a first drawing step of drawing the undrawn yarn to obtain a first drawn yarn; a second drawing step of further drawing the first drawn yarn to obtain a second drawn yarn; and a relaxation step of relaxing the second drawn yarn in the longitudinal direction, wherein the total drawing ratio is 520% ​​or more and 1500% or less.

[11] The method for producing modacrylic fibers according to

[10] , further comprising a drying step between the first drawing step and the second drawing step.

[12] The method for producing modacrylic fibers according to

[10] or

[11] , wherein the weight-average molecular weight of the polymer is 100,000 or more.

[13] A method for producing modacrylic fibers according to any one of

[10] to

[12] , wherein the stretching ratio of the second stretching step is 170% or more.

[0010] According to the present invention, it is possible to provide a high-strength modacrylic fiber that can exhibit sufficient performance on its own when applied to fabrics, etc., and a method for producing said modacrylic fiber.

[0011] ≪Modacrylic Fiber≫ The modacrylic fiber according to the first embodiment has a content of acrylonitrile-derived constituent units relative to the mass of modacrylic resin of 54% by mass or more and less than 85% by mass, and an infrared absorption spectrum of 1400 to 1480 cm⁻¹ －１ [-CH ２ The dichromatic ratio R of [-] is 0.48 or less.

[0012] According to the modacryl fiber of the first embodiment, the infrared absorption spectrum is 1400-1480 cm⁻¹. －１ Since the dichromatic ratio R in this material is below a specific value, high-strength modacrylic fibers can be provided.

[0013] The modacryl fiber according to the second embodiment has a content of acrylonitrile-derived constituent units relative to the mass of modacryl resin of 54% by mass or more and less than 85% by mass, and an infrared absorption spectrum of 2220 to 2260 cm⁻¹. －１ The dichromatic ratio R of [-CN] is 0.40 or less.

[0014] According to the modacryl fiber of the second embodiment, the infrared absorption spectrum is 2220-2260 cm⁻¹. －１ Since the dichromatic ratio R in this material is below a specific value, high-strength modacrylic fibers can be provided.

[0015] The modacrylic fibers according to the first embodiment and the modacrylic fibers according to the second embodiment differ in that their dichromatic ratio R is defined based on different wavenumbers, but they are substantially the same fibers. Hereafter, unless otherwise specified, both will be referred to collectively as "modacrylic fibers of this embodiment."

[0016] As described above, the modacryl fiber of this embodiment contains a modacryl resin in which the content of constituent units derived from acrylonitrile is within a specific range, and has a specific dichromatic ratio R. The essential or optional components contained in the modacryl fiber will be described below.

[0017] <Modacrylic resin> As mentioned above, the modacrylic resin has a content of acrylonitrile (a1)-derived constituent units relative to the mass of the modacrylic resin of 54% by mass or more and less than 85% by mass. Specifically, the modacryl resin is preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) is 54% by mass or more and less than 85% by mass relative to the mass of the modacryl resin, and the content of constituent units derived from other monomers (a2) other than acrylonitrile is 15% by mass or more and 46% by mass or less relative to the mass of the modacryl resin; more preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) is 54% by mass or more and 80% by mass or less relative to the mass of the modacryl resin, and the content of constituent units derived from other monomers (a2) other than acrylonitrile is 20% by mass or more and 46% by mass or less relative to the mass of the modacryl resin; and even more preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) is 54% by mass or more and 70% by mass or less relative to the mass of the modacryl resin, and the content of constituent units derived from other monomers (a2) other than acrylonitrile is 30% by mass or more and 46% by mass or less relative to the mass of the modacryl resin. However, in the above modacryl resin, the total content of constituent units derived from acrylonitrile (a1) and constituent units derived from other monomers other than acrylonitrile (a2) is 100% by mass.

[0018] (Other monomers (a2)) Other monomers (a2) other than acrylonitrile may be any ethylenically unsaturated monomer other than acrylonitrile, and are not particularly limited. Examples of the above other monomers (a2) include halogen-containing vinyl monomers, halogen-containing vinylidene monomers, sulfonic acid group-containing monomers, etc. Among these, from the viewpoint of spinning stability and flame retardancy, one or more monomers selected from the group consisting of halogen-containing vinyl monomers and sulfonic acid group-containing monomers are preferred.

[0019] Examples of halogen-containing vinyl monomers include vinyl chloride, vinyl bromide, and vinyl iodide. Of these, vinyl chloride is preferred. Halogen-containing vinyl monomers may be used individually or in combination of two or more types.

[0020] Examples of sulfonic acid group-containing monomers include allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, isoprene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and their metal salts such as sodium salts and amine salts. Among these, styrene sulfonic acid and the metal salts of 2-acrylamido-2-methylpropane sulfonic acid are preferred. Sulfonic acid group-containing monomers may be used individually or in combination of two or more types.

[0021] More specifically, the modacryl resin is preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) is 54% by mass or more and less than 85% by mass relative to the mass of the modacryl resin, and the content of constituent units derived from halogen-containing vinyl monomer (a2-1) is 15% by mass or more and 46% by mass relative to the mass of the modacryl resin. More preferably, the modacryl resin is preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) is 54% by mass or more and 80% by mass relative to the mass of the modacryl resin, and the content of constituent units derived from halogen-containing vinyl monomer (a2-1) is 20% by mass or more and 46% by mass relative to the mass of the modacryl resin. However, in the above modacryl resin, the total content of constituent units derived from acrylonitrile (a1) and constituent units derived from halogen-containing vinyl monomer (a2-1) is 100% by mass.

[0022] Furthermore, a more specific alternative embodiment of the modacryl resin is preferably a copolymer in which the content of constituent units derived from acrylonitrile (a1) relative to the mass of the modacryl resin is 55% by mass or more and 80% by mass or less, the content of constituent units derived from halogen-containing vinyl monomer (a2-1) relative to the mass of the modacryl resin is 16% by mass or more and 44% by mass or less, and the content of constituent units derived from sulfonic acid group-containing vinyl monomer (a2-2) relative to the mass of the modacryl resin is 0.5% by mass or more and 4% by mass or less. More preferably, the content of constituent units derived from acrylonitrile (a1) relative to the mass of the modacryl resin is 57% by mass or more and 80% by mass or less, the content of constituent units derived from halogen-containing vinyl monomer (a2-1) relative to the mass of the modacryl resin is 16% by mass or more and 42% by mass or less, and the content of constituent units derived from sulfonic acid group-containing vinyl monomer (a2-2) relative to the mass of the modacryl resin is 0.5% by mass or more and 4% by mass or less. However, in the above modacryl resin, the total content of constituent units derived from acrylonitrile (a1), constituent units derived from halogen-containing vinyl monomer (a2-1), and constituent units derived from sulfonic acid group-containing vinyl monomer (a2-2) is 100% by mass.

[0023] (Other components) Modacrylic fibers may contain components other than modacrylic resin (hereinafter also referred to as "other components") within the fiber, as long as they do not impair the effects of the present invention. Examples of other components include flame retardants, stabilizers, lubricants, processing aids, etc.

[0024] The flame retardant preferably includes at least one selected from the group consisting of, for example, antimony compounds, compounds containing tin and zinc, and magnesium compounds. Among these, compounds containing tin and zinc and magnesium compounds are preferred due to their low environmental impact, and magnesium compounds are preferred from the viewpoint of flame retardancy.

[0025] The antimony compound is not particularly limited, and examples thereof include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, and the like. The compound containing tin and zinc is not particularly limited, and examples thereof include zinc stannate hydroxide and the like. The magnesium compound is not particularly limited, and examples thereof include magnesium hydroxide, magnesium oxide, and the like.

[0026] The content of the flame retardant is preferably 0.5 parts by mass or more and 40 parts by mass or less, more preferably 1 part by mass or more and 20 parts by mass or less, relative to 100 parts by weight of the modacrylic resin.

[0027] Examples of the stabilizer include epoxy heat stabilizers, hydrotalcite heat stabilizers, tin-based heat stabilizers, Ca-Zn-based heat stabilizers, β-diketone heat stabilizers, and the like.

[0028] Examples of the lubricant include fatty acid ester-based lubricants, hydrocarbon-based lubricants, fatty acid-based lubricants, higher alcohol-based lubricants, aliphatic amide-based lubricants, metal soap-based lubricants, and the like.

[0029] Examples of the processing aid include (meth)acrylate-based polymers, styrene-acrylonitrile copolymers, and the like.

[0030] The weight average molecular weight of the modacrylic resin is preferably 100,000 or more and 400,000 or less, more preferably 110,000 or more and 360,000 or less, and even more preferably 120,000 or more and 330,000 or less, from the viewpoint of excellent fiber strength.

[0031] <Dichroic Ratio R> Dichroic ratio R is defined, using an infrared spectrophotometer, as the absorption intensity ratio of two linearly polarized lights that vibrate perpendicular to each other among light incident on a modacrylic fiber. In the case of the modacrylic fiber according to the first embodiment, the dichroic ratio R corresponds to light of 1400 to 1480 cm －１ -1, where A1 is the absorbance when the polarization direction is parallel to the MD direction of the modacrylic fiber, and A2 is the absorbance when the polarization direction is perpendicular to the MD direction, the dichroic ratio R is represented by the ratio (A1 / A2). Further, in the case of the modacrylic fiber according to the second embodiment, the dichroic ratio R corresponds to light of 2220 to 2260 cm －１If A1 is the absorbance of the modacryl fiber when the light is parallel to the MD direction, and A2 is the absorbance when the light is perpendicular, then it is expressed as the ratio of these two values ​​(A1 / A2). Infrared absorption spectrum 1400–1480 cm⁻¹ －１ The dichromatic ratio R is the methylene chain [-CH] that constitutes the main chain of modacrylic fiber. ２ This represents the orientation of the infrared absorption spectrum from 2220 to 2260 cm⁻¹. －１ The dichromatic ratio R represents the orientation of the nitrile groups [-CN] contained in the modacryl fibers.

[0032] In the case of modacrylic fibers according to the first embodiment, from the viewpoint of excellent fiber strength, the dichromatic ratio R is 0.48 or less, preferably 0.47 or less, more preferably 0.46 or less, even more preferably 0.45 or less, and particularly preferably 0.44 or less. In the case of modacrylic fibers according to the second embodiment, from the viewpoint of excellent fiber strength, the dichromatic ratio R is 0.40 or less, preferably 0.39 or less, more preferably 0.38 or less, even more preferably 0.37 or less, and particularly preferably 0.36 or less.

[0033] <Physical Properties of Modacrylic Fibers> (Shrinkage Rate) From the viewpoint of excellent heat resistance, modacrylic fibers preferably have a shrinkage rate of 20% or less at 180°C, more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0034] (LOI) Modacrylic fibers are preferably LOI values ​​of 26 or higher, and more preferably 30 or higher, from the viewpoint of excellent flame retardancy.

[0035] (Tensile Strength) Modacrylic fibers are preferably tensile strength of 3.2 cN / dtex or higher, more preferably 3.4 cN / dtex or higher, even more preferably 3.6 cN / dtex or higher, even more preferably 3.8 cN / dtex or higher, and particularly preferably 4.0 cN / dtex or higher, from the viewpoint of having excellent fiber strength.

[0036] (Single fiber fineness) The single fiber fineness of modacrylic fibers is not particularly limited, but from the viewpoint of processability for spinning and fabric production, it is preferably 0.1 dtex or more and 10 dtex or less.

[0037] <Application> The aforementioned modacrylic fibers are excellent in fiber strength and heat resistance. Therefore, when the modacrylic fiber is applied to a fabric, sufficient performance can be exerted even when used alone.

[0038] <Fabric> The fabric according to the present embodiment contains at least the aforementioned modacrylic fiber.

[0039] <<Method for Producing Modacrylic Fiber>> The method for producing a modacrylic fiber according to the present embodiment described above comprises: a step of obtaining an undrawn yarn by wet-spinning a spinning dope containing a polymer, wherein the content of structural units derived from acrylonitrile relative to the mass of the polymer is 54 mass% or more and less than 85 mass%; a first drawing step of drawing the undrawn yarn to obtain a first drawn yarn; a second drawing step of further drawing the first drawn yarn to obtain a second drawn yarn; and a relaxation step of relaxing the second drawn yarn in the longitudinal direction, in this order. In the first drawing step and the second drawing step, the total draw ratio is 520% or more and 1500% or less.

[0040] According to the above production method, in the spinning step of a specific polymer that provides modacrylic fibers with a high content of structural units derived from acrylonitrile, drawing is performed to achieve a specific total draw ratio, whereby high-strength modacrylic fibers can be obtained.

[0041] <Step of Obtaining Undrawn Yarn> (Polymer) The polymer refers to the modacrylic resin described above. Therefore, the description of embodiments of the polymer used in the present production method is omitted. A commercially available product may be used as the polymer (modacrylic resin), or a polymer obtained by a known polymerization method may be used.

[0042] (Wet spinning) The spinning stock is preferably a solution in which the polymer is dissolved in a solvent such as dimethyl sulfoxide. The polymer concentration of the spinning stock is not particularly limited, but is usually preferably 20% by mass or more and 70% by mass or less. Wet spinning can be carried out by known methods, for example, by extruding the spinning stock from a spinning nozzle into a solvent-water coagulation bath to form a yarn, and then drawing the yarn. The temperature of the coagulation bath is also not limited, and is, for example, in the range of 15°C to 40°C.

[0043] <First stretching step> The first stretching step can be carried out, for example, in a solvent-water system or a water stretching bath. The primary stretching ratio is preferably 150% or more, more preferably 200% or more, and even more preferably 230% or more. Note that, for example, a stretching ratio of 150% is equivalent to a stretching ratio of 1.5 times.

[0044] <Second stretching step> The second stretching step can be carried out, for example, in a solvent-water stretching bath, a water stretching bath, or in a heated atmosphere. The secondary stretching ratio is preferably 170% or more, more preferably 200% or more, and even more preferably 230% or more.

[0045] <Total Draw Ratio> In the first and second drawing processes described above, the total draw ratio is 520% ​​to 1500%, preferably 550% to 1200%, more preferably 600% to 1000%, even more preferably 650% to 1000%, even more preferably 700% to 1000%, particularly preferably 750% to 1000%, and most preferably 800% to 1000%. High-strength modacrylic fibers can be obtained by drawing to a specific total draw ratio. The total draw ratio is calculated from the primary draw ratio × secondary draw ratio.

[0046] <Relaxation Process> The relaxation process is carried out under conditions that provide excellent heat resistance, for example, at a temperature of 120°C to 200°C and at a concentration of 7% to 20%.

[0047] (Other steps) The method for producing modacrylic fibers may include other steps (hereinafter also referred to as "other steps") other than the step of obtaining undrawn yarn by wet spinning, the first drawing step, the second drawing step, and the relaxation step, as long as the effects of the present invention are not impaired. Other steps may include, for example, a washing step between the first drawing step and the second drawing step, a drying step between the first drawing step and the second drawing step, and a heating step after the relaxation step.

[0048] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0049] First, we will explain the various measurement and evaluation methods. (1) Measurement of the acrylonitrile content of the polymer composition The nitrogen content in the polymer was measured using a Yanaco CHN coder, and this nitrogen content was considered to be the nitrogen content derived from acrylonitrile, and the acrylonitrile content in the polymer was calculated.

[0050] (2) Measurement of the molecular weight of the polymer The molecular weight was measured in terms of standard polystyrene by gel permeation chromatography (GPC) according to the measurement conditions described below. GPC unit: HLC-8320GPC manufactured by Tosoh Corporation Column: TSKgel SuperAWM-H manufactured by Tosoh Corporation Eluent: N,N-dimethylformamide manufactured by Nacalai Tesque Corporation Flow rate: 0.4 ml / min Detector: Differential refractometer

[0051] (3) Method for measuring fiber shrinkage rate The prepared fibers were bundled so that the total fineness was 3333 dtex and cut to a length of 5 mm. The fiber shrinkage rate was measured using a TMA (thermomechanical analyzer [product name "TMA7100C" manufactured by Hitachi, Ltd.], gas used: nitrogen, gas flow rate: 500 mL / min, heating rate: 5 °C / min, load 18 mN) under a load of 0.0054 mN / dtex while raising the temperature from 30 °C to 350 °C. If the initial sample length is X and the sample length at an arbitrary temperature is Y, the fiber shrinkage rate is expressed by the following formula: Fiber shrinkage rate (%) = 100 - (Y / X) × 100

[0052] (4) Single fiber strength The single fiber strength of the prepared fibers was measured in accordance with JIS L1015.

[0053] (5) Measurement of LOI value 0.25 g of the fiber to be measured is taken, defibrated, and then a twisted string of approximately 5 cm or longer is made. Each of these twisted strings is placed upright in the holder of the oxygen index measuring machine, and a flame is brought close from above to burn it. The minimum oxygen concentration required for the twisted string sample to continue burning for 5 cm is measured and this is defined as the LOI value.

[0054] (6) Measurement of the dichromatic ratio R Each single fiber was directly plated in KBr and measured using a microtransmission method with an FT / IR-6X Fourier transform infrared spectrophotometer (manufactured by JASCO Corporation) and an IRT-5200 infrared microscope (manufactured by JASCO Corporation). The spectrum with polarization parallel to the length direction of the fiber [polarizer angle 0 degrees] was taken as the parallel absorption spectrum A1, and the spectrum with polarization perpendicular to it [polarizer angle 90 degrees] was taken as the perpendicular absorption spectrum A2. The peak heights from the baseline of the parallel absorption and perpendicular absorption of each absorption peak were taken as A1' and A2', respectively, and the dichromatic ratio R of each absorption peak was calculated as R = A1' / A2'.

[0055] <Examples of Modacrylic Fiber Preparation> Below are examples of the preparation of modacrylic resin and modacrylic fibers. In modacrylic resin, constituent units derived from acrylonitrile are referred to as "acrylonitrile units" and are written as "AN units" in Tables 1 and 2. Constituent units derived from vinyl chloride are referred to as "vinyl chloride units" and are written as "VC units" in Tables 1 and 2. Constituent units derived from p-styrenesulfonate sodium are referred to as "p-styrenesulfonate sodium units" and are written as "NaSS units" in Tables 1 and 2. Constituent units derived from 2-acrylamide-2-methylpropanesulfonate sodium are referred to as "2-acrylamide-2-methylpropanesulfonate sodium units" and are written as "AMPS Na units" in Tables 1 and 2.

[0056] (Example A1) Polymerization was carried out using a pressure-resistant polymerization reactor with a capacity of 14 L. As an initial charge, 183 g of acrylonitrile, 1361 g of vinyl chloride, 13.4 g of sodium bisulfite, 120 mg of ferrous sulfate, 11.4 g of sulfuric acid, 37.0 g of sodium lauryl sulfate, and 6400 g of deionized water were added, and the temperature was raised to 53°C, and polymerization was carried out for 7 hours. During the polymerization reaction, 1525 g of acrylonitrile, 61 g of sodium p-styrenesulfonate, and 4.7 g of ammonium persulfate were continuously added. The obtained polymer latex was heated to 90°C, and sodium chloride was added to salt out the mixture to obtain a polymer slurry. The polymer slurry was filtered, washed with hot water, dehydrated, and dried to obtain a polymer with a content of 58.2% by mass of acrylonitrile units, 39.8% by mass of vinyl chloride units, and 2.0% by mass of sodium p-styrene sulfonate units, and a weight-average molecular weight of 148,079, with a polymerization conversion rate of 91.5% by mass. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning solution with a stock solution concentration of 22% by mass. This spinning solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, withdrawn at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. The material was then washed with water, dried at 140°C for 7 minutes, then stretched to 2.5 times its original length at 150°C, relaxed by 12% at 170°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 552% and a single fiber fineness of 1.7 dtex.

[0057] (Example A2) Except that the amount of ferrous sulfate used was 10 mg in Example A1, the same method as in Example A1 was used to obtain a polymer with an acrylonitrile unit content of 61.1% by mass, a vinyl chloride unit content of 36.9% by mass, a p-styrene sulfonate sodium unit content of 2.0% by mass, and a weight-average molecular weight of 306,183. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning solution with a stock solution concentration of 14% by mass. This spinning solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. The fibers were then washed with water, dried at 140°C for 7 minutes, stretched to 2.5 times their original length at 170°C, relaxed by 10% at 180°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 565% and a single fiber fineness of 1.7 dtex.

[0058] (Example A3) 100 parts by mass of the polymer obtained in Example A2 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 14% by mass. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then stretched 4.0 times at 170°C, relaxed by 10% at 180°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 900% and a single fiber fineness of 1.7 dtex.

[0059] (Example A4) Polymerization was carried out using a pressure-resistant polymerization reactor with a capacity of 14 L. As an initial charge, 350 g of acrylonitrile, 600 g of vinyl chloride, 21.0 g of sodium bisulfite, 130 mg of ferrous sulfate, 11.0 g of sulfuric acid, and 5700 g of deionized water were added, and the temperature was raised to a predetermined 50°C, and polymerization was carried out for a polymerization time of 5 hours and 40 minutes. During the polymerization reaction, 2450 g of acrylonitrile, 105 g of sodium 2-acrylamido-2-methylpropanesulfonate, and 10.5 g of ammonium persulfate were continuously added. The obtained slurry was filtered, washed with hot water, dehydrated, and dried to obtain a polymer with a weight-average molecular weight of 130,446, containing 79.0% by mass of acrylonitrile units, 18.0% by mass of vinyl chloride units, and 3.0% by mass of sodium 2-acrylamido-2-methylpropanesulfonate units, with a polymerization conversion rate of 97.0% by mass. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a spinning stock solution with a stock solution concentration of 22% by mass. This spinning stock solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, withdrawn at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. The material was then washed with water, dried at 140°C for 7 minutes, then stretched to 2.5 times its original length at 150°C, relaxed by 4% at 170°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 602% and a single fiber fineness of 1.56 dtex.

[0060] (Example A5) 100 parts by mass of the polymer obtained in Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 14% by mass. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then stretched 3.0 times at 170°C, relaxed by 10% at 180°C, and heat treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 660% and a single fiber fineness of 1.7 dtex.

[0061] (Example A6) 100 parts by mass of the polymer obtained in Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 14% by mass. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then stretched 3.5 times at 170°C, relaxed by 10% at 180°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 770% and a single fiber fineness of 1.7 dtex.

[0062] (Example A7) 100 parts by mass of the polymer obtained in Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 14% by mass. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then stretched 4.0 times at 170°C, relaxed by 10% at 180°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 880% and a single fiber fineness of 1.7 dtex.

[0063] (Comparative Example A1) Polymerization was carried out using a pressure-resistant polymerization reactor with a capacity of 14 L. As an initial charge, 146 g of acrylonitrile, 2025 g of vinyl chloride, 19.3 g of sodium bisulfite, 90 mg of ferrous sulfate, 11.0 g of sulfuric acid, 31.8 g of sodium lauryl sulfate, and 5700 g of deionized water were added, and the temperature was raised to a predetermined 49°C, and polymerization was carried out for a time of 5 hours and 40 minutes. During the polymerization reaction, 1485 g of acrylonitrile, 73 g of sodium p-styrenesulfonate, and 10.5 g of ammonium persulfate were continuously added. The obtained polymer latex was heated to 90°C, and sodium chloride was added to salt out the mixture to obtain a polymer slurry. The polymer slurry was filtered, washed with hot water, dehydrated, and dried to obtain a polymer with a weight-average molecular weight of 94,595 and a polymerization conversion rate of 92.3% by mass, containing 46.4% by mass of acrylonitrile units, 51.6% by mass of vinyl chloride units, and 2.0% by mass of p-styrene sulfonate sodium units. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a spinning solution with a stock solution concentration of 28% by mass. This spinning solution was extruded into a 47% aqueous dimethyl sulfoxide solution at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, withdrawn at 3.0 m / min, and stretched 2.5 times in a 50% aqueous dimethyl sulfoxide solution at 85°C. The fibers were then washed with water, dried at 140°C for 7 minutes, stretched to 2.5 times their original length at 130°C, relaxed by 14% at 150°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 540% and a single fiber fineness of 1.7 dtex.

[0064] (Comparative Example A2) 100 parts by mass of the polymer obtained in Example A2 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 14% by mass. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes to obtain modacrylic fibers with a total stretch ratio of 250% and a single fiber fineness of 3.75 dtex.

[0065] (Comparative Example A3) 100 parts by mass of the polymer obtained in Comparative Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 28% by mass. This spinning stock solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 3.0 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then relaxed by 14% at 150°C and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 645% and a single fiber fineness of 1.7 dtex.

[0066] (Comparative Example A4) 100 parts by mass of the polymer obtained in Comparative Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to prepare a spinning stock solution with a stock solution concentration of 28% by mass. This spinning stock solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 3.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then relaxed by 14% at 150°C and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 753% and a single fiber fineness of 1.7 dtex.

[0067] (Example B1) A polymer with a weight-average molecular weight of 306,183 was obtained using the same method as in Example A2, except that the amount of substance used was increased 20 times. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a resin solution with a stock solution concentration of 14% by mass. To the obtained resin solution, magnesium hydroxide was added in an amount of 5 parts by mass per 100 parts by mass of the polymer to prepare the spinning stock solution. This spinning stock solution was extruded into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. The fibers were then washed with water, dried at 140°C for 7 minutes, stretched 3.5 times at 170°C, relaxed by 10% at 180°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 788% and a single fiber fineness of 1.7 dtex.

[0068] (Example B2) Except that the amount of ferrous sulfate used was 30 mg in Example A1, the same method was used to obtain a polymer with a polymer content of 59.2% by mass of acrylonitrile units, 38.8% by mass of vinyl chloride units, and 2.0% by mass of sodium styrene sulfonate units, and a weight-average molecular weight of 192,200, with a polymerization conversion rate of 91.5% by mass. 100 parts by mass of the obtained polymer and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a resin solution with a concentration of 20% by mass. To the obtained resin solution, magnesium hydroxide was added in an amount of 5 parts by mass per 100 parts by mass of the polymer to prepare the spinning stock. The spinning solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After washing with water, it was dried at 140°C for 7 minutes, then stretched 3.5 times at 150°C, relaxed by 12% at 170°C, and heat-treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 770% and a single fiber fineness of 1.7 dtex.

[0069] (Example B3) 100 parts by mass of the polymer obtained in Example A2 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a resin solution with a stock solution concentration of 14% by mass. To the obtained resin solution, magnesium hydroxide was added in an amount of 5 parts by mass per 100 parts by mass of the polymer to prepare a spinning stock solution. This spinning stock solution was extruded using a nozzle with a pore size of 0.07 mm and 2000 holes into a 65% by mass aqueous solution of dimethyl sulfoxide at 20°C, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After that, it was washed with water, dried at 140°C for 7 minutes, then stretched 2.5 times at 170°C, relaxed by 10% at 180°C, and heat treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 565% and a single fiber fineness of 1.7 dtex.

[0070] (Comparative Example B1) 100 parts by mass of the polymer obtained in Comparative Example A1 and 0.8 parts by mass of polyglycidyl methacrylate were dissolved in dimethyl sulfoxide to obtain a resin solution with a stock solution concentration of 28% by mass. To the obtained resin solution, magnesium hydroxide was added in an amount of 5 parts by mass per 100 parts by mass of the polymer to prepare a spinning stock solution. This spinning stock solution was extruded into a 47% by mass aqueous solution of dimethyl sulfoxide at 20°C using a nozzle with a pore size of 0.07 mm and 2000 holes, drawn back at 3.0 m / min, and stretched 2.5 times in a 50% by mass aqueous solution of dimethyl sulfoxide at 85°C. After that, it was washed with water, dried at 140°C for 7 minutes, then stretched 2.6 times at 130°C, relaxed by 14% at 150°C, and heat treated for 2 minutes to obtain modacrylic fibers with a total stretch ratio of 559% and a single fiber fineness of 1.7 dtex.

[0071] The results obtained for the modacryl fibers in each of the above examples and comparative examples are shown in Tables 1 and 2.

[0072]

[0073]

[0074] Tables 1 and 2 show that when producing modacrylic fibers using a specific modacrylic resin that yields modacrylic fibers, stretching the fibers to a specific total stretch ratio results in the dichromatic ratio R obtained from the IR spectrum being below a specific value, and as a result, high-strength modacrylic fibers can be obtained.

Claims

1. The content of constituent units derived from acrylonitrile relative to the mass of the modacryl resin is 54% by mass or more and less than 85% by mass, and the infrared absorption spectrum is 1400-1480 cm⁻¹. －１ [-CH ２ Modacrylic fiber having a dichromatic ratio R of 0.48 or less.

2. The content of constituent units derived from acrylonitrile relative to the mass of the modacryl resin is 54% by mass or more and less than 85% by mass, and the infrared absorption spectrum is 2220 to 2260 cm⁻¹. －１ Modacrylic fiber having a dichromatic ratio R of [-CN] of 0.40 or less.

3. The modacrylic fiber according to claim 1 or 2, wherein the weight-average molecular weight is 100,000 or more and 400,000 or less.

4. The modacryl fiber according to claim 1 or 2, wherein the content of constituent units derived from halogen-containing vinyl monomers relative to the mass of modacryl resin is 15% by mass or more and 46% by mass or less.

5. Modacrylic fiber according to claim 1 or 2, wherein the fiber contains at least one selected from the group consisting of antimony compounds, compounds containing tin and zinc, and magnesium compounds.

6. The modacrylic fiber according to claim 1 or 2, wherein the shrinkage rate at 180°C is 20% or less.

7. Modacrylic fiber according to claim 1 or 2, wherein the LOI value is 26 or higher.

8. The modacrylic fiber according to claim 1 or 2, wherein the tensile strength is 3.2 cN / dtex or greater.

9. A fabric comprising the modacrylic fiber described in claim 1 or 2.

10. A method for producing modacrylic fiber, comprising the steps of: wet spinning a spinning stock containing a polymer having a content of acrylonitrile-derived structural units relative to the mass of the polymer of 54% by mass or more and less than 85% by mass to obtain an undrawn yarn; a first drawing step of drawing the undrawn yarn to obtain a first drawn yarn; a second drawing step of further drawing the first drawn yarn to obtain a second drawn yarn; and a relaxation step of relaxing the second drawn yarn in the longitudinal direction, wherein the total drawing ratio is 520% ​​or more and 1500% or less.

11. A method for producing modacrylic fibers according to claim 10, comprising a drying step between the first stretching step and the second stretching step.

12. The method for producing modacrylic fibers according to claim 10 or 11, wherein the weight-average molecular weight of the polymer is 100,000 or more.

13. The method for producing modacrylic fibers according to claim 10 or 11, wherein the stretching ratio of the second stretching step is 170% or more.

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