Polyamide fiber, method for producing the same, and fiber structure

Abstract

The present invention provides a polyamide fiber with excellent high color rendering properties, a method for producing the same, and a fiber structure. The polyamide fiber is formed from a polyamide resin composition, the polyamide resin composition comprising a polyamide resin and an amino-containing color modifier, and the polyamide fiber has a terminal amino group concentration of 5.0 to 40.0 μeq / g. In addition, such a fiber can be obtained by a production method having at least the following steps: a melt-kneading step of melt-kneading a polyamide resin composition comprising a polyamide resin and an amino-containing color modifier to obtain a melt having a given melt viscosity; and a spinning step of spinning the melt-kneaded product to form fibers.

Description

[0001] Related Applications

[0002] This application claims the priority of Japanese Patent Application No. 2019-206559 filed in Japan on November 14, 2019, the entire contents of which are incorporated by reference as a part of this application. Technical Field

[0003] The present invention relates to a polyamide fiber having excellent color development properties, a method for producing the same, and a fiber structure. Background Art

[0004] Polyamide resins are crystalline linear polymers that have an amide bond (-CONH-) as a repeating unit in the molecular chain. As resins with excellent chemical resistance and cold resistance, there are polyamide 9, polyamide 10, polyamide 11, polyamide 12, etc. As resins with elasticity, there are polyamide elastomers, etc.

[0005] Among the grades of polyamide resins, there are resins for which dyeability is improved. For example, Patent Document 1 (International Publication No. 2017 / 146018) discloses a polyamide elastomer composition comprising a polyamide elastomer and a phosphorous acid compound in order to improve dyeability and dyeing fastness, wherein the content of the phosphorous acid compound is 0.02 mass % or more and 0.15 mass % or less relative to the polyamide elastomer, and the terminal amino group concentration of the polyamide elastomer is 2.0×10 -5 The polyamide elastomer composition can be used as a molded body, fiber, clothing button, linear zipper, etc.

[0006] In addition, Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-189773) discloses a combined fiber having a two-component split structure of a component containing a polyamide elastomer and a component containing a polyester resin, wherein the content of the polyamide elastomer in the fiber is 40 to 80% by weight. The combined fiber has excellent dyeability and can obtain a texture with a cool touch and good tactile feel.

[0007] Patent Document 1: International Publication No. 2017 / 146018

[0008] Patent Document 2: Japanese Patent Application Publication No. 2010-189773 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in order to improve dyeability and dye fastness, the polyamide elastomer composition of Patent Document 1 must add a phosphorous acid compound and adjust the terminal amine group during melt polymerization, which not only reduces the hand feel that is a characteristic of the polyamide elastomer fiber, but also has an impact on the deterioration of spinnability and the complication of the process, resulting in increased costs. In addition, in Patent Document 2, although dyeability is obtained by compounding with polyester, there is a problem that the hand feel and functionality (softness, hydrolysis resistance, etc.) that are characteristics of the polyamide elastomer are impaired.

[0011] Therefore, an object of the present invention is to provide a polyamide-based fiber that has excellent color development properties and can be used without impairing the properties of the polyamide-based resin, a method for producing the same, and a fiber structure.

[0012] Solutions to the problem

[0013] The present inventors have conducted in-depth research to achieve the above-mentioned purpose, and as a result, they have found that by combining a polyamide resin used for fiberization with an amino-containing color modifier to form a resin composition, and utilizing the amino-containing color modifier to make the concentration of terminal amino groups in the fiber reach a specific value, it is possible to obtain polyamide fibers having excellent color development and maintaining the characteristics of polyamide resins, thereby completing the present invention.

[0014] That is, the present invention can be constituted in the following aspects.

[0015] [Method 1]

[0016] A polyamide fiber, which is formed by a polyamide resin composition (a polyamide resin composition comprising a polyamide resin and an amino-containing color developing modifier), wherein the polyamide resin composition comprises a polyamide resin and an amino-containing color developing modifier, and the polyamide fiber has a terminal amino group concentration of 5.0 to 40.0 μeq / g (preferably 10.0 to 35.0 μeq / g, more preferably 12.0 to 30.0 μeq / g).

[0017] [Method 2]

[0018] The polyamide-based fiber according to aspect 1, wherein the polyamide-based resin is composed of a polyamide-based resin having a repeating unit including a linear or branched saturated aliphatic hydrocarbon group having 1 to 22 carbon atoms.

[0019] [Method 3]

[0020] The polyamide-based fiber according to aspect 1 or 2, wherein the polyamide-based resin contains a polyamide-based elastomer.

[0021] [Method 4]

[0022] The polyamide-based fiber according to any one of aspects 1 to 3, wherein the amino group-containing color development improving agent is composed of a polyamide oligomer (the amino group-containing color development improving agent contains a polyamide oligomer).

[0023] [Method 5]

[0024] The polyamide-based fiber according to aspect 4, wherein the number average molecular weight of the polyamide oligomer is 500 to 10,000 (preferably 500 to 9,000, more preferably 1,000 to 6,000).

[0025] [Method 6]

[0026] The polyamide-based fiber according to any one of aspects 1 to 5, wherein the terminal amino group concentration of the amino-containing color development improving agent is 100 to 2000 μeq / g (preferably 125 to 2000 μeq / g, more preferably 200 to 1000 μeq / g).

[0027] [Method 7]

[0028] The polyamide fiber according to any one of aspects 1 to 6, wherein the mass ratio of the polyamide resin to the amino group-containing color development improving agent is 99 / 1 to 70 / 30 (preferably 98 / 2 to 75 / 25, more preferably 95 / 5 to 80 / 20) in terms of former / latter.

[0029] [Method 8]

[0030] The polyamide-based fiber according to any one of aspects 1 to 7, wherein the shape of a melting peak shown in a DSC curve obtained by differential scanning calorimetry is a single peak.

[0031] [Method 9]

[0032] A fiber structure comprising the polyamide-based fiber according to any one of aspects 1 to 8.

[0033] [Method 10]

[0034] A method for producing polyamide fibers as described in any one of methods 1 to 8, the method comprising at least: a melt-kneading step of melt-kneading a polyamide resin composition comprising a polyamide resin and an amino color modifier to obtain a melt having a given melt viscosity; and a spinning step of spinning the melt-kneaded product to form fibers.

[0035] Effects of the Invention

[0036] The polyamide fibers of the present invention can improve the color development of the fibers by controlling the terminal amino group concentration to a specific value using the amino group-containing color development improver, thereby taking advantage of the characteristics of the polyamide resin constituting the polyamide fibers. DETAILED DESCRIPTION

[0037] The polyamide fiber of the present invention is obtained by spinning a polyamide resin composition comprising a polyamide resin and an amino group-containing color development improver.

[0038] (Polyamide resin)

[0039] The polyamide resin has at least a repeating unit in which divalent hydrocarbon groups which may have a substituent are linked via an amide bond, and for example, has at least any of the repeating units represented by the following formulae (1) to (3).

[0040] -NH-R1-NH- (1)

[0041] -CO-(R2) m -CO- (2)

[0042] -NH-R3-CO- (3)

[0043] Here, R1, R2, and R3 are the same or different, are hydrocarbon groups having 1 to 22 carbon atoms, and m is an integer of 0 or 1.

[0044] Formula (1) is a repeating unit derived from a diamine compound, formula (2) is a repeating unit derived from a dicarboxylic acid compound, and formula (3) is a repeating unit derived from a lactam or an ω-aminocarboxylic acid.

[0045] Examples of the hydrocarbon group having 1 to 22 carbon atoms include a linear or branched saturated aliphatic hydrocarbon group having 1 to 22 carbon atoms (preferably 6 to 20, more preferably 9 to 18), a linear or branched saturated alicyclic hydrocarbon group having 6 to 22 carbon atoms (preferably 6 to 20, more preferably 6 to 18), and a linear or branched aromatic hydrocarbon group having 6 to 22 carbon atoms (preferably 6 to 20, more preferably 6 to 18). Substituents may be present in these hydrocarbon groups within the range that the effects of the present invention are not impaired.

[0046] Among them, from the viewpoint of spinnability, polyamide resins having repeating units containing linear or branched saturated aliphatic hydrocarbon groups having 2 to 22 carbon atoms are preferred, and in particular, from the viewpoint of imparting high functionality, polyamide resins having repeating units containing linear or branched saturated aliphatic hydrocarbon groups having 6 to 20 carbon atoms (preferably 9 to 18 carbon atoms) are preferred.

[0047] Preferred polyamide-based resins include polyamide 6, polyamide 6 / 6, polyamide 6 / 10, polyamide 6 / 11, polyamide 6 / 12, polyamide 9, polyamide 10, polyamide 11, polyamide 12, and polyamide MXD6.

[0048] As highly functional polyamide resins having excellent chemical resistance, cold resistance, etc., polyamide resins having a CH2 group with a long carbon number (aliphatic polyamide resins) such as polyamide 9, polyamide 10, polyamide 11, and polyamide 12 are preferred.

[0049] The polyamide resin may include not only non-elastomers but also polyamide elastomers. Polyamide elastomers are preferred because they can impart a unique texture to the fiber.

[0050] The polyamide elastomer may be a polyether block polyamide, polyester block polyamide, or polyester ether block polyamide having the above-mentioned polyamide resin component as a hard segment and a polyether block or a polyester block as a soft segment.

[0051] The polyether block may be a linear or branched saturated aliphatic polyether having 2 to 10 carbon atoms, preferably a segment having 2 to 6 carbon atoms between ether bonds, for example, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, polypentamethylene glycol, polyhexamethylene glycol, etc.

[0052] There are no particular limitations as long as the chain has spinnability, and the ratio (mass ratio) of the hard segment to the soft segment may be, for example, about 50 / 50 to 95 / 5, preferably about 60 / 30 to 92 / 8, and more preferably about 70 / 30 to 90 / 10.

[0053] The polyamide elastomer may have, for example, an aliphatic polyamide having 6 to 22 carbon atoms as a hard segment, preferably an aliphatic polyamide having 9 to 20 carbon atoms as a hard segment. Here, the aliphatic polyamide refers to a polyamide in which the hydrocarbon group in the repeating unit of the above formulae (1) to (3) is a saturated aliphatic hydrocarbon group.

[0054] Specifically, for example, it may be a polyether block polyamide having polyamide 6, polyamide 6 / 6, polyamide 6 / 11, polyamide 6 / 12, polyamide 9, polyamide 11, or polyamide 12 as a hard segment and having polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or the like as a soft segment.

[0055] (Contains amino color modifier)

[0056] The amino-containing color development improver has at least an amino group and can be used together with a polyamide resin to impart a given terminal amino group concentration to polyamide fibers. The terminal amino group concentration of the amino-containing color development improver can be, for example, 100 to 2000 μeq / g, preferably 125 to 2000 μeq / g, and more preferably 200 to 1000 μeq / g.

[0057] As for the amino-containing color developing improver, as long as the characteristics of the polyamide resin exerted in the polyamide fiber are not impaired, it can be combined in an appropriate ratio according to the type of the amino-containing color developing improver. For example, from the viewpoint of color development and compatibility, the mass ratio of the polyamide resin to the amino-containing color developing improver can be, for example, 99 / 1 to 70 / 30, preferably 98 / 2 to 75 / 25, and more preferably 95 / 5 to 80 / 20 in terms of the former / the latter.

[0058] It should be noted that the proportion of the polyamide resin (especially the polyamide elastomer resin) in the polyamide fibers (especially the polyamide elastomer fibers) may be, for example, 70 to 99% by mass, preferably 75 to 98% by mass, and more preferably 80 to 95% by mass.

[0059] Examples of the amino group-containing color development improver include amino group-containing compounds such as polyamide oligomers and polyamines from the viewpoint of improving the color development of polyamide-based fibers without impairing the characteristics of polyamide-based resins.

[0060] The polyamide oligomer is preferably composed of any repeating unit among the repeating units represented by formulas (1) to (3) described for the polyamide resin. Examples of the hydrocarbon group having 1 to 22 carbon atoms used in the repeating units represented by formulas (1) to (3) include a straight chain or branched saturated aliphatic hydrocarbon group having 1 to 22 carbon atoms (preferably 6 to 20, more preferably 9 to 18), a straight chain or branched saturated alicyclic hydrocarbon group having 6 to 22 carbon atoms (preferably 6 to 20, more preferably 6 to 18), and a straight chain or branched aromatic hydrocarbon group having 6 to 22 carbon atoms (preferably 6 to 20, more preferably 6 to 18). These hydrocarbon groups may have a substituent within the range that does not impair the effects of the present invention.

[0061] Preferred polyamide oligomers include polyamide 6 oligomer, polyamide 4 / 6 oligomer, polyamide 6 / 6 oligomer, polyamide 6 / 10 oligomer, polyamide 6 / 11 oligomer, polyamide 6 / 12 oligomer, polyamide 9 oligomer, polyamide 10 oligomer, polyamide 11 oligomer, and polyamide 12 oligomer.

[0062] From the viewpoint of compatibility with the polyamide resin, the hydrocarbon groups of the repeating units of the polyamide oligomer and the polyamide resin preferably have the same number of carbon atoms. For example, the number of carbon atoms of the hydrocarbon groups of the repeating units in the polyamide oligomer may be within the range of ±3 of the number of carbon atoms in the repeating units of the polyamide resin, preferably within the range of ±2 of the number of carbon atoms in the repeating units of the polyamide resin, and more preferably within the range of ±1 of the number of carbon atoms in the repeating units of the polyamide resin. It should be noted that, when the polyamide resin is a polyamide elastomer, the hydrocarbon groups of the repeating units of the polyamide resin component in the hard segment preferably have the above relationship.

[0063] The number average molecular weight of the polyamide oligomer may be, for example, 500 to 10000, preferably 500 to 9000, and more preferably 1000 to 6000. Here, the molecular weight of the polyamide oligomer is a value measured by the method described in Examples below.

[0064] The polyamine has a structure having 3 to 12 amino groups and is not limited to a monomer or a polymer, and may be a linear aliphatic, alicyclic or aromatic polyamine (diamine, triamine, tetramine, etc.).

[0065] The polyamide resin composition used in the present invention may contain various commonly used additives as required. As additives, for example, heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, antistatic agents, colorants (such as coloring pigments), smoothing agents, plasticizers, antibacterial agents, mildewproof agents, deodorants and other additives may be mentioned. The polyamide resin composition used in the present invention may contain other thermoplastic resins within the scope of not hindering the effect of the present invention.

[0066] From the viewpoint of making fiberization good, the melt viscosity of the polyamide resin composition used in the present invention at 240°C is preferably 600 to 3000 poise. When the melt viscosity exceeds 3000 poise, the high-speed spinning property during fiberization is sometimes reduced. In addition, when the melt viscosity is less than 600 poise, it is sometimes easy to break the yarn during spinning, the productivity is insufficient, and the strength of the obtained fiber is sometimes reduced. The melt viscosity of the polyamide resin composition is more preferably 800 to 2000 poise.

[0067] The polyamide resin composition used in the present invention preferably has good compatibility with the amino group-containing color improvement agent. For example, the polyamide resin preferably has a single peak in the shape of the melting peak shown in the DSC curve obtained by differential scanning calorimetry (DSC).

[0068] It should be noted that whether the shape of the melting peak is a single peak can be determined by investigating the DDSC curve obtained by differentiating the DSC curve. The DDSC curve refers to a curve obtained by first-order differentiation of the DSC curve with time, representing the slope of the DSC curve. Therefore, when the slope of the DSC curve becomes zero, the value of the DDSC curve becomes zero, and therefore, at the maximum and minimum values ​​in the DSC curve, the value of the DDSC curve becomes zero. That is, in the melting peak shown in the DSC curve, when the point at which the value of the DDSC curve becomes zero is only one point, it can be judged that the shape of the melting peak is a single peak.

[0069] The polyamide fiber of the present invention can be obtained by a known method as long as it can be spun, for example, it can be spun by melt spinning of a polyamide resin composition. As melt spinning, there can be cited spinning-stretching method, direct stretching method, POY (partially oriented yarn)-DTY (draw-textured yarn) method, etc. Alternatively, the polyamide resin composition can be fiberized by melt blowing method, electrostatic spinning method, etc.

[0070] For example, a method for producing polyamide fibers may include a melt-kneading step of melt-kneading a polyamide resin composition to obtain a melt having a predetermined melt viscosity, and a spinning step of spinning the melt-kneaded product to form fibers.

[0071] For example, in the melt-kneading process, an amino-containing color-developing modifier can be added to a polyamide resin and melt-kneaded, or a polyamide resin composition (masterbatch) containing an amino-containing color-developing modifier can be temporarily formed and the polyamide resin and the masterbatch can be further mixed and melt-spun to fiberize.

[0072] Furthermore, by using an amino group-containing color development improver in the spinning step, the melt viscosity of the polyamide resin composition can be adjusted to a viscosity suitable for spinning, and the spinnability can be improved compared to the case of spinning a polyamide resin alone.

[0073] In addition, since the polyamide-based fibers of the present invention have excellent color development properties, the process may further include a dyeing step of the obtained fibers. The dyeing step may be performed by a known method depending on the dye used.

[0074] Examples of the dye include acid dyes, acid mordant dyes, metal complex acid dyes, disperse dyes, etc. Among them, acid dyes, acid mordant dyes, and metal complex acid dyes are preferred from the viewpoint of color development and spinnability.

[0075] Acid dyes are dyes containing sulfonic acid groups, carboxyl groups, hydroxyl groups, etc. as solubilizing groups, and examples thereof include acid dyes such as azo dyes, triphenylmethane dyes, anthraquinone dyes, xanthene dyes, phthalocyanine dyes, indigo dyes, nitroso dyes, and pyrazolone dyes.

[0076] Acid mordant dyes are dyes that have color development due to acid dyes and are mainly capable of metal complexation (for example, coordination bonding with chromium atoms), and examples include acid mordant dyes such as azo, triphenylmethane, anthraquinone, oxyanthene, phthalocyanine, indigo, nitroso and pyrazolone.

[0077] Metal complex acid dyes are roughly classified into 1:1 type dyes in which one metal atom is bonded to one dye molecule, and 1:2 type dyes in which one metal atom is bonded to two dye molecules. Examples of metal complex acid dyes include azo, triphenylmethane, anthraquinone, oxyanthene, phthalocyanine, indigo, nitroso and pyrazolone.

[0078] (Polyamide fiber)

[0079] The terminal amino group concentration of the polyamide fiber of the present invention is 5.0 to 40.0 μeq / g, preferably 10.0 to 35.0 μeq / g, and more preferably 12.0 to 30.0 μeq / g. In the polyamide fiber, the concentration of the terminal amino group present in the fiber can be increased by using an amino-containing color development improver. On the other hand, if the terminal amino group concentration exceeds the above upper limit, the properties of the polyamide resin (for example, washing fastness, etc.) may sometimes be deteriorated compared to the case where the amount of the amino-containing color development improver added is too much.

[0080] The polyamide fiber of the present invention may be a monofilament yarn or a multifilament yarn. In addition, it may be a composite fiber (e.g., core-sheath type, island-in-sea type, side-by-side type, etc.), but even a non-composite fiber can exhibit good color rendering properties.

[0081] The cross-sectional shape of the polyamide fiber of the present invention can be any known or commonly used shape, and can be a solid circular cross-sectional shape, or a special-shaped cross-sectional shape (for example, a flat, elliptical, triangular or other polygonal cross-sectional shape). In addition, it can also be a hollow cross-sectional shape.

[0082] The fineness of the polyamide fiber of the present invention is not particularly limited. Depending on the application, for example, the single fiber fineness may be in the range of about 0.1 to 1000 dtex, preferably 1 to 100 dtex, and more preferably 2 to 50 dtex. For example, when used for fabrics, the single fiber fineness may be 1 to 10 dtex, or 1 to 5 dtex.

[0083] The fiber strength of the polyamide fiber of the present invention at room temperature is 1.0 cN / dtex or more, for example, preferably 1.0 to 10 cN / dtex, more preferably 2.0 to 10 cN / dtex or more. Here, the fiber strength is a value measured according to the JIS L 1013 test method.

[0084] The polyamide fiber of the present invention has excellent color rendering properties, particularly excellent color rendering properties in dark dyeing such as dark navy blue, dark brown, black, etc. The polyamide fiber of the present invention, for example, in dark dyeing, may have an L* value of 20 or less, preferably 19 or less, and more preferably 18 or less. It should be noted that the L* value is a value measured by the method described in the Examples described below.

[0085] The polyamide fiber of the present invention also has good washing fastness, and can show, for example, grade 4 or higher in the washing fastness test defined in JIS L 0844.

[0086] The polyamide-based fiber of the present invention also has good light fastness, and can show, for example, grade 3 or higher in the light fastness test defined in JIS L 0842.

[0087] The polyamide fibers of the present invention can have particularly excellent texture when the base resin is a polyamide elastomer. Here, the texture means that the fiber has excellent grip (non-slip property).

[0088] (Fiber structure)

[0089] The present invention includes a fiber structure comprising the above-mentioned polyamide fibers. The fiber structure may be a one-dimensional structure such as continuous fibers (monofilament yarn, multifilament yarn), short fibers (cut fibers), threads, ribbons, ropes, etc., or a fabric such as a woven fabric, a knitted fabric, or a non-woven fabric comprising the above-mentioned polyamide fibers. The fiber structure may be composed of polyamide fibers alone or in combination with other fibers.

[0090] Example

[0091] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0092] [Terminal amino group concentration (NH2)]

[0093] About 1 g of polyamide fiber or sample containing amino color modifier was dissolved in 40 mL of phenol / methanol mixed solvent (volume ratio: 9 / 1), thymol blue was added as an indicator to the obtained sample solution, and titration was performed with N / 20 hydrochloric acid to measure the terminal amino group concentration NH2 (μeq / g).

[0094] [Melt viscosity]

[0095] In order to reproduce the melt viscosity during spinning, an amino-containing color modifier was added to the polyamide resin composition and extruded to produce pellets. The pellets were prepared using the "capilograph 1C PMD-C" manufactured by Toyo Seiki Seisaku-sho, Ltd. at 240°C and a shear rate of 1000 sec. -1 The melt viscosity was measured under the conditions of .

[0096] [Number average molecular weight]

[0097] The number average molecular weight (Mn) was calculated from the terminal amino group concentration (NH2) and the terminal carboxyl group concentration (COOH) by the following formula.

[0098] Mn = 2 / (terminal amino concentration (NH2) + terminal carboxyl concentration (COOH))

[0099] In addition, the terminal carboxyl group concentration (COOH) was measured as follows.

[0100] About 0.5 g of a polyamide fiber or a sample containing an amino color modifier was dissolved in 50 mL of benzyl alcohol, phenolphthalein was added as an indicator to the obtained sample solution, and titration was performed with N / 20 potassium hydroxide / methanol solution to measure the terminal carboxyl group concentration COOH (μeq / g).

[0101] [Spinning properties]

[0102] The occurrence of fuzz and broken fibers when spinning 100 kg of polyamide fibers was evaluated.

[0103] ○: No fluff / broken yarn during spinning

[0104] △: 1 to 2 times of fuzz / filament breakage occurred during spinning

[0105] ×: Fluff or yarn breakage occurred more than 3 times during spinning

[0106] [Compatibility with amino-containing color modifiers]

[0107] The shape of the melting peak shown in the DSC curve obtained by differential scanning calorimetry (DSC) of polyamide fibers was evaluated to see whether it was a single peak. It should be noted that the above measurement was performed using "TA-4000" manufactured by METTLER TOLEDO, and the DSC curve was obtained by measuring to 300°C at a heating rate of 10°C / min in a nitrogen atmosphere.

[0108] ○: The shape of the melting peak is a single peak

[0109] ×: The shape of the melting peak is not a single peak.

[0110] [Fiber density]

[0111] The fiber fineness was measured according to JIS L 1013 “Testing methods for chemical filament yarns”.

[0112] [L* value]

[0113] The fibers obtained in the examples and comparative examples were made into woven fabrics, and the L* value was measured using a spectrophotometer "CM-3700A" manufactured by Konica Minolta, Inc. under the following conditions: mirror reflection treatment: SCE, measurement diameter: LAV (25.4 mm), UV condition: 100% Full, field of view: 2 degrees, and main light source: C light source.

[0114] [Washing fastness]

[0115] The fibers obtained in Examples and Comparative Examples were made into woven fabrics and measured in accordance with the measuring method of JIS L 0844 B-4.

[0116] [Light fastness]

[0117] The fibers obtained in the examples and comparative examples were made into woven fabrics and measured in accordance with the ultraviolet carbon arc measurement method of JIS L 0842.

[0118] [strength]

[0119] According to JIS L 1013, the breaking elongation (initial tensile strength) was determined under the conditions of a test length of 20 cm, an initial load of 0.1 g / d, and a tensile speed of 10 cm / min, and the average value of 5 or more points was adopted.

[0120] [Feel evaluation]

[0121] The fibers obtained in the examples and comparative examples were made into braids, and a gripping property confirmation test was performed by 10 subjects. It should be noted that in the test, the non-slip properties when touching the braid were evaluated compared with the braids made in the same manner from polyamide 12 fibers that are not elastic. The evaluation criteria are as follows.

[0122] ◎: 10 people felt that it was not easy to slide

[0123] ○: 8-9 people felt that it was not easy to slide

[0124] △: 5-7 people felt that it was not easy to slide

[0125] ×: Less than 4 people felt that the product was not easy to slide

[0126] [Example 1]

[0127] (1) Preparation of polyamide 12 oligomer

[0128] The autoclave was purged with nitrogen, 1.000 g of laurolactam and 38 g of dodecanediamine were added together with a small amount of water and a small amount of phosphoric acid, and the resulting mixture was stirred under heating. The temperature of the reaction system was slowly raised while adjusting the pressure with nitrogen to 17.5 kgf / cm 2 (1.7×10 6 Pa), and continue heating and stirring for about 4 hours. Next, the reaction system is slowly restored to normal pressure, and a very small amount of nitrogen is further circulated. The decompression takes about 1 hour to discharge the water in the system. Then, while the system is cooled at normal pressure, the polyamide 12 oligomer is taken out in a molten state. The obtained polyamide 12 oligomer is further cooled to obtain a slightly brittle solid. The number average molecular weight of the polyamide 12 oligomer is about 5400, which is a low molecular weight, and the content of terminal amino groups is 350μeq / g. The polyamide 12 oligomer is used as an amino-containing color modifier.

[0129] (2) Preparation of polyamide 12 elastomer fiber

[0130] Polyamide elastomer fibers were produced according to the following method: a polyamide 12 elastomer ("VESTAMID E47-S1" manufactured by DAICEL EVONIK) was used as a polyamide resin, to which the above-described polyamide 12 oligomer as an amino-containing color modifier was added in a weight ratio of 9%, and the fibers were melted by an extruder and ejected from a spinning nozzle at 250°C.

[0131] After cooling the filaments ejected from the spinning nozzle using a 1.0 m long transverse blowing type cooling air device, the filaments were continuously introduced into a tubular heater (inner wall temperature: 130°C) with a length of 1.0 m and an inner diameter of 30 mm, which was set 1.3 m below the spinning spinneret, and stretched in the tubular heater. Then, a spinning oil was applied to the fiber taken out from the tubular heater, and then the fiber was wound up at a withdrawal speed of 3000 m / min via a roller to obtain a polyamide 12 elastomer fiber with a length of 84 dtex / 24 filament (dtex / 24f). The terminal amino concentration of the fiber was 17.6 μeq / g. The fiber was used to make a fiber with a unit weight of 200 g / m 2 The tubular knitted fabric was scoured and then dyed with Kayanol Milling Black TLB (4% owf) at a bath ratio of 1:50 at 80°C for 40 minutes, and various measurements were performed.

[0132] [Example 2]

[0133] The polyamide 12 elastomer fiber was obtained by spinning in the same manner as in Example 1 except that the polyamide 12 oligomer was added in a weight ratio of 20%. The terminal amino group concentration of the fiber was 38.5 μeq / g. The fiber was used to prepare a tubular knitted fabric in the same manner as in Example 1, dyed, and subjected to various measurements.

[0134] [Example 3]

[0135] The polyamide 12 elastomer fiber was obtained by spinning in the same manner as in Example 1 except that the polyamide 12 oligomer was added in such a manner that the weight ratio was 6%. The terminal amino group concentration of the fiber was 12.1 μeq / g. The fiber was used to prepare a tubular knitted fabric in the same manner as in Example 1, dyed, and subjected to various measurements.

[0136] [Comparative Example 1]

[0137] Except that no polyamide 12 oligomer was added, spinning was performed in the same manner as in Example 1 to obtain polyamide 12 elastomer fibers. The terminal amino group concentration of the fibers was 4.0 μeq / g. The fibers were used to prepare tubular knitted fabrics in the same manner as in Example 1, dyed, and subjected to various measurements.

[0138] [Comparative Example 2]

[0139] The polyamide 12 elastomer fiber was obtained by spinning in the same manner as in Example 1 except that the polyamide 12 oligomer was added in a weight ratio of 35%. The terminal amino group concentration of the fiber was 63.8 μeq / g. The fiber was used to prepare a tubular knitted fabric in the same manner as in Example 1, dyed, and subjected to various measurements.

[0140] Table 1 shows the properties of the obtained polyamide 12 elastomer fibers.

[0141]

[0142] In Examples 1 to 3, the amino-containing color development modifier is combined with the polyamide resin to be fiberized, so the spinnability is good. In addition, the color development of the obtained fiber is good, and not only the washing fastness but also the light fastness are excellent. Moreover, the feel of the obtained fiber can be exerted as a polyamide elastomer and fiberized, and the feel of the obtained fiber is excellent.

[0143] On the other hand, in Comparative Example 1, the fiberization of the polyamide elastomer was carried out without using the amino-containing color improvement agent, and the spinnability was insufficient. Moreover, the color development of the obtained fiber was insufficient, and the washing fastness and light fastness were also poor compared with Examples 1 to 3. In Comparative Example 2, the terminal amino group concentration was increased, and therefore the amount of the amino-containing color improvement agent added was increased, resulting in insufficient spinnability. Moreover, compared with Examples 1 to 3, the strength of the obtained fiber was reduced, and the washing fastness and light fastness were also poor. In addition, the proportion of the amino-containing color improvement agent became higher, and as a result, the elastomer component in the fiber became less, and as a result, the feel of the fiber was also poor compared with Examples 1 to 3.

[0144] Industrial Applicability

[0145] The polyamide fibers of the present invention can bring out the characteristics of polyamide resins and improve their color rendering properties. Therefore, as fiber structures such as cloth and rope formed from the above-mentioned polyamide fibers, they are useful in, for example, various clothing (outerwear, underwear, uniforms, surgical gowns, hospital gowns, white coats, operating clothes, swimsuits, ski suits, aprons, hats, aprons, socks, gloves, scarves, etc.), various daily necessities (bedding, quilt covers, pillow covers, beds, bedspreads, blankets, sheets, bath mats, towels, tablecloths, curtains, shower curtains, nets, doorknob gloves, diaper bags, slippers, etc.), building materials (carpets, curtains, etc.), industrial materials (ropes, etc.), and agricultural, forestry and fishery materials (fishing nets, etc.).

Claims

1. A polyamide fiber, which is formed from a polyamide resin composition, wherein the polyamide resin composition comprises a polyamide resin and an amino-containing color developing modifier, wherein the terminal amino group concentration of the polyamide fiber is 5.0 to 40.0 μeq / g, The amino-containing color modifier is composed of polyamide oligomers. The number average molecular weight of the polyamide oligomer is 500 to 10,000.

2. The polyamide fiber according to claim 1, wherein The polyamide-based resin is composed of a polyamide-based resin having a repeating unit including a linear or branched saturated aliphatic hydrocarbon group having 1 to 22 carbon atoms.

3. The polyamide fiber according to claim 1 or 2, wherein The polyamide-based resin includes a polyamide-based elastomer.

4. The polyamide fiber according to claim 1 or 2, wherein The amino-containing color developing improver has a terminal amino group concentration of 100 to 2000 μeq / g.

5. The polyamide fiber according to claim 1 or 2, wherein The mass ratio of the polyamide resin to the amino-containing color developing improver is 99 / 1 to 70 / 30.

6. The polyamide fiber according to claim 1 or 2, wherein: The shape of the melting peak shown in the DSC curve obtained by differential scanning calorimetry is a single peak. 7 . A fiber structure comprising the polyamide fiber according to claim 1 .

8. A method for producing the polyamide fiber according to any one of claims 1 to 6, the method comprising at least: A melt-kneading step of melt-kneading a polyamide resin composition containing a polyamide resin and an amino group-containing color development modifier to obtain a melt having a predetermined melt viscosity; and The spinning step is to spin the melt-kneaded product into fibers.

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