JP7173014B2 - Polyamide fiber, woven and knitted fabric, and method for producing polyamide fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to polyamide fibers having excellent color developability and color fastness.

Polyamide fibers such as polycapramide and polyhexamethylene adipamide are widely used for clothing and industrial materials because of their excellent mechanical properties, chemical resistance and heat resistance. In particular, it is used in many clothing applications due to its excellent strength, abrasion resistance, and the like. In recent years, the diversification of fashion and the expansion of applications have progressed, and improved performance is required for innerwear, sportswear, casual wear, and the like. In recent years, in particular, there has been an increasing demand for polyamide fibers that are excellent in color development, particularly matte color development.

Various proposals have been made so far as techniques for improving the dyeability of polyamide fibers. For example, Patent Document 1 proposes a multicolored bulky yarn made of synthetic fibers with different dyeability. As an example, a polymer with a large amount of NH ₃ terminal groups that is well dyed by acid dyes and a polymer that is lightly dyed by acid dyes are proposed. Combinations of polymers with a low amount of _NH3 end groups are described. Further, Patent Document 2 proposes a polyamide fiber containing 3 to 6.5% titanium oxide and an amino terminal group content of 4×10 ⁻⁵ to 8×10 ⁻⁵ mol/g.

Polyamide fibers have amide bonds and amino terminal groups capable of forming ionic bonds with dye molecules in the fiber structure, so that they are dyed with ionic bonding dyes (such as acid dyes) with good color development. Therefore, as described in Patent Documents 1 and 2, techniques have been developed in which the more the number of amino terminal groups, the more the number of dyeing sites for the dye, and the more the dyeability and color developability are improved.

JP-A-7-189067 Japanese Patent Application Laid-Open No. 2004-292982

However, although the polyamide exemplified in Patent Document 1 is described as a polymer with a large amount of _NH3 terminal groups that is well dyed with acid dyes, there is no disclosure of a specific amount of _NH3 terminal groups, but color development is not It can be inferred that it will improve. In addition, polyamide fibers for use in carpets before multicolor bulking processing are partially oriented yarns, and thus have a problem of inferior color fastness from the viewpoint of fiber structure. Although the oriented yarn has a small amount of amorphous portion, the partially oriented yarn is a yarn whose oriented portion is partially oriented.

Dyeing fastness means the degree of durability of dyeing to various external conditions such as sunlight, washing, perspiration, friction, acid, and ironing. Practically, it is indicated by light fastness, washing fastness, and the like. In addition, the polyamide fiber described in Patent Document 2 specifies the amount of amino terminal groups for clothing applications, and although the color developability is improved, the more the amount of titanium oxide, which is a white pigment, the more the color developability decreases, and the fiber orientation is likely to become loose, and from the viewpoint of the fiber structure, there is a problem that the dyeing fastness is inferior.

As described above, the polyamide fibers disclosed in Patent Documents 1 and 2 can be obtained as polyamide fibers having excellent color development properties, but there is a problem that the polyamide fibers for clothing applications, which have strict standards for color fastness, have poor color fastness. rice field.

Accordingly, an object of the present invention is to provide a polyamide fiber having excellent color developability and fastness.

The above problems can be solved by the following configuration.
(1) A polyamide fiber containing an aliphatic polyamide as a main component, wherein the amount of amino terminal groups in the aliphatic polyamide is 7.0×10 ⁻⁵ mol/g or more and 10.0×10 ⁻⁵ mol/g or less, A polyamide fiber having a rigid amorphous content of 40% or more, which is required for the polyamide fiber.
(2) The polyamide fiber according to (1), which contains 0.1% by weight to 10.0% by weight of titanium oxide relative to the total amount of the fiber.
(3) The polyamide fiber according to (1) or (2), having a total fineness of 5 to 235 dtex.
(4) A knitted fabric for clothing comprising the polyamide fiber according to any one of (1) to (3).
(5) A method for producing a polyamide fiber, in which a polyamide resin raw material is melted, the polyamide resin is discharged from a spinneret, cooled and solidified to form a thread, and the thread is drawn, heat-treated, and then wound. The polyamide resin raw material contains an aliphatic polyamide, the amino terminal group amount in the aliphatic polyamide fiber is 7.0 × 10 ^-5 mol / g or more and 10.0 × 10 ^-5 mol / g or less, and the following A method for producing a polyamide fiber, comprising steps (a) to (d).
(a) A discharge step in which the take-up speed is from 1300 m/min to 2400 m/min.
(b) A drawing step in which the yarn is drawn by the draft ratio of the take-up roller and the drawing roller, the temperature of the drawing roller is 150 to 190° C., and the draw ratio is 1.7 to 3.0 times.
(c) A relaxation treatment step in which the yarn is relaxed between the drawing roller and the take-up roller after the drawing treatment, and the relaxation rate is 0 to 2.0%.
(d) A winding step in which the winding speed is 3000 to 4500 m/min.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a polyamide fiber excellent in color developability and color fastness.

The polyamide fiber of the present invention will be described in detail below.
The polyamide used for the polyamide fiber of the present invention is a high molecular weight body in which a so-called hydrocarbon group is linked to the main chain via an amide bond, and may be produced by polycondensation reaction using aminocarboxylic acid and cyclic amide as raw materials. Alternatively, it may be produced by a polycondensation reaction using a dicarboxylic acid and a diamine as raw materials. Hereinafter, these high molecular weight raw materials are referred to as monomers. Monomers are not limited to petroleum-derived monomers, biomass-derived monomers, mixtures of petroleum-derived monomers and biomass-derived monomers, and the like. Examples of such polyamides include, but are not limited to, polycaproamide, polyundecanolactam, polylauryllactam, polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylene dodecane diamide, and the like. Among these, polycaproamide is preferable because it is excellent in spinnability and mechanical properties and is resistant to gelation.

In addition to the most contained monomer components (for example, cyclic amide, or dicarboxylic acid and diamine), the polyamide fiber in the present invention copolymerizes or mixes the second and third components within the scope of the purpose of the present invention. can be The copolymerization component can include structural units derived from, for example, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, aliphatic diamines, alicyclic diamines, and aromatic diamines.

In the present invention, "a polyamide fiber containing an aliphatic polyamide as a main component" is a polyamide copolymer fiber containing an aliphatic polyamide component as a main component. Here, the term "main component" means that the proportion of the aliphatic polyamide in the total polyamide component is 90% by weight or more. In addition, when both the main monomer and the monomer to be copolymerized form an aliphatic polyamide, the total content of them should be 90% by weight or more.

The viscosity of the polyamide in the present invention may be selected within a common range of viscosity for producing clothing fibers, but it is preferable to use a polymer with a 98% sulfuric acid relative viscosity of 2.0 or more and 4.0 or less. . By setting it within such a range, a practicable raw yarn strength can be obtained. Furthermore, since the optimum tension is applied during stretching and heat setting, the crystallization and orientation of the polyamide are promoted, the rigid amorphous content is increased, the value is appropriate, and the color fastness is improved, which is preferable. On the other hand, when the sulfuric acid relative viscosity is 4.0 or less, it is possible to produce with a melt viscosity suitable for spinning, which is preferable.

In addition, various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent whitening agents, antistatic agents, and moisture absorbing agents may be added to the polyamide fiber of the present invention. Agents (polyvinylpyrrolidone, etc.), antibacterial agents (silver zeolite, zinc oxide, etc.), etc., may be added as needed between 0.001 and 10% by weight of the total polyamide fiber.

The amino terminal group content of the polyamide fiber of the present invention is 7.0×10 ⁻⁵ mol/g or more. Since the amino terminal group serves as a dye seat, an amino terminal group amount of 7.0×10 ⁻⁵ mol/g or more provides color developability suitable for clothing applications. If it is less than 7.0×10 ⁻⁵ mol/g, the amino terminal groups on which the dye sits are insufficient, resulting in poor color development and difficulty in application to clothing. Also, although the amount of amino terminal groups is preferably as large as possible, the upper limit thereof in the present invention is about 10×10 ⁻⁵ mol/g. It is preferably 7.5×10 ⁻⁵ mol/g or more, more preferably 8.0×10 ⁻⁵ mol/g or more.

Rigid amorphous refers to amorphous whose amount is determined by the method described in the Examples section, and is an intermediate state between crystal and mobile amorphous (conventional complete amorphous). , the molecular motion is frozen even at the glass transition temperature (Tg) or higher, and it is an amorphous material that becomes a fluid state at a temperature higher than Tg (for example, Minoru Totoki, ``DSC (3)-Polymer Glass Transition Behavior-", Journal of the Society of Fiber Science and Technology (Textiles and Industry), Vol.65, No.10 (2009)). The rigid amorphous amount (percentage) is expressed as 100%-crystallinity-mobile amorphous amount.

In the present invention, the polyamide fiber includes a crystalline portion, a rigid amorphous portion and a movable amorphous portion.

Further, the rigid amorphous content required in the polyamide fiber is 40% or more. When the rigid amorphous content is 40% or more, the dye placed in the movable amorphous portion is suppressed, and the dye selectively sits on the amino terminal group, so that excellent color development and excellent color fastness are exhibited. do. If the rigid amorphous content is less than 40%, a large amount of dye is distributed in the movable amorphous portion, and therefore the dye is removed from the movable amorphous portion in fastness evaluation, and excellent color fastness cannot be obtained. The rigid amorphous content is preferably as large as possible, preferably 42% or more, more preferably 45% or more. The upper limit in the present invention is about 50% from the viewpoint of productivity. The rigid amorphous portion retains the dye and provides superior colorfastness compared to the mobile amorphous portion which is more susceptible to dye removal.

The polyamide fiber of the present invention preferably contains 0.1 to 10.0% by weight of titanium oxide with respect to the total amount of the fiber. Titanium oxide is known as an excellent white pigment and is widely used in synthetic fibers as a matting agent. Because of its white pigment, when it is contained in fibers, the appearance of clothing becomes whitish, making it difficult to obtain deep colors. If the content of titanium oxide is increased, the color tends to have a high degree of whiteness (pastel tone), and the dyeability is lowered. In particular, the polyamide fiber of the present invention has an amino terminal group amount of 7 × 10 ^-5 mol / g or more, so that even if it contains titanium oxide, the number of dyes that can be seated on the amino terminal group increases, so that the dyeability is improved. It is preferable because it improves and the effect of dyeability appears more remarkably. The amount of titanium oxide is preferably 0.3 to 5.0% by weight, more preferably 1.5 to 3.0% by weight, based on the total amount of fibers. As the titanium oxide, an inert one generally used as a white pigment is preferable, and titanium oxide having an average particle size of 1 μm or less is preferably used in order to prevent deterioration of the physical properties of the fiber.

The polyamide fiber of the present invention preferably has a tensile strength of 2.5 cN/dtex or more. More preferably, it is 3.0 cN/dtex or more. By setting it to such a range, it is possible to provide clothing excellent in strength that can withstand actual use in clothing applications such as innerwear and sportswear.

The polyamide fiber of the present invention preferably has an elongation of 35% or more. A preferred range is 35-50%. By setting the content within such a range, it is possible to obtain a fiber that has good color developability and color fastness and is suitable for use in clothing, which is preferable. In addition, process passability in higher processes such as weaving, knitting, and false twisting is improved.

The polyamide fiber of the present invention preferably has a total fineness of 5 to 235 decitex and a filament number of 1 to 144 filaments as a multifilament considering that it is used as a long fiber material for clothing. When the fineness of the single yarn is reduced, softness is obtained, but the appearance of the clothing product becomes whitish due to diffused reflection of light, making it difficult to obtain a deep color, and moreover, the dye is easily removed from the amorphous portion. The total fineness is preferably 5 to 235 dtex from the viewpoint of the texture, color development, and color fastness required for clothing. In particular, the polyamide fiber of the present invention has an amino terminal group content of 7 × 10 ^-5 mol / g or more and a rigid amorphous content of the fiber of 40% or more. Since the dye is seated on the amino terminal group and the dye placed in the movable amorphous portion is suppressed, the effects of color development and color fastness are more pronounced. More preferably, the total fineness is 5-110 decitex.

The cross-sectional shape of the polyamide fiber of the present invention is preferably circular, triangular, flat, lens-shaped (flat-convex), bean-shaped (flat-concave), Y-shaped, cross-shaped, or star-shaped.

Next, the method for producing the aliphatic polyamide fiber of the present invention will be explained.
The method for producing the polyamide polymer used for the polyamide fiber of the present invention is not particularly limited. A polyamide having a desired amount of amino groups and a desired titanium oxide content can be produced by adding a diamine, which is an amino terminal group amount adjusting agent, and titanium oxide, which is a matting agent, to a polyamide monomer and performing known polycondensation. can. The diamine and titanium oxide can be added at the raw material stage, or added during the polycondensation reaction. Further, by blending two or more of the produced polyamide polymers, it is possible to obtain desired amino group content and titanium oxide content. The blending method is not particularly limited, and examples thereof include melt blending using an extruder or the like and dry blending in which pellets are mixed.

Examples of diamines as amino terminal group modifiers include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1 ,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,15-diaminopentadecane, 1, Aliphatic such as 16-diaminohexadecane, 1,17-diaminoheptadecane, 1,18-diaminooctadecane, 1,19-diaminononadecane, 1,20-diaminoeicosane, 2-methyl-1,5-diaminopentane Alicyclic diamines such as diamines, cyclohexanediamine, bis-(4-aminohexyl)methane, and aromatic diamines such as xylylenediamine.

The relative viscosity of the polyamide polymer used for the polyamide fiber of the present invention is preferably 2.0 or more as the relative viscosity at 25° C. of a 98% sulfuric acid solution with a sample concentration of 0.01 g/mL. More preferably 2.05 to 7.0, particularly preferably 2.1 to 6.5, most preferably 2.15 to 6.0. When the relative viscosity is 2.0 or more, the yarn strength of the polyamide fiber can be expressed, and when it is 8.0 or less, the melt spinnability is not difficult, which is preferable.

The polyamide polymer used for the polyamide fiber of the present invention may further contain a known terminal blocking agent for molecular weight adjustment. A monocarboxylic acid is preferred as the terminal blocking agent. In addition, acid anhydrides such as phthalic anhydride, monoisocyanates, monocarboxylic acid halides, monoesters, and monoalcohols can be used. The monocarboxylic acid that can be used as a terminal blocking agent is not particularly limited as long as it is reactive with an amino group, and examples include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, and lauric acid. , tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, aliphatic monocarboxylic acids such as isobutyric acid, alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid, benzoic acid, toluic acid, α-naphthalenecarboxylic acid, Aromatic monocarboxylic acids such as β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid and phenylacetic acid can be mentioned. In the present invention, one or more of these monocarboxylic acids may be used.

The polyamide fibers of the present invention can be produced on known melt spinning equipment. As an example of known melt spinning, polyamide resin pellets or the like are melted, weighed and transported by a gear pump, discharged from a spinneret, and cooled to room temperature by blowing cooling air with a yarn cooling device such as a chimney. Cool to and make yarn. The yarn is lubricated and bundled by a lubricating device, entangled by a fluid entangling nozzle device, and passed through a take-off roller and a drawing roller. At that time, the film is drawn according to the ratio of the peripheral speeds of the take-up roller and the drawing roller. Further, the yarn is heat-treated by heating the drawing roller, and then wound up by a winder (winding device) to produce a polyamide fiber.

For the polyamide fiber of the present invention, the polyamide polymer used for melt spinning has a sulfuric acid relative viscosity of 2.0 to 4.0, and the melting temperature for melt spinning is higher than 20 ° C. and lower than 85 ° C. relative to the melting point of the polyamide. At the same time, in order to keep the atmospheric temperature under the nozzle at a high temperature, the heater temperature of the steam seal should be 200 ° C. or higher, and the cooling start distance should be 30 to 170 mm in order to slowly cool the polyamide polymer discharged from the discharge hole under the nozzle. , a take-up roller speed of 1,300 to 2,400 m/min, a draw ratio of 1.7 to 3.0, and a take-up speed of 3,000 m/min to 4,500 m/min.

In particular, when the take-up roller is taken off at a low speed range (1300 to 2400 m/min), orientation relaxation before stretching proceeds, and proper orientation and crystallization proceeds during stretching. Further, heat treatment is preferably performed using the stretching roller as a heating roller, and the heat treatment temperature is preferably 150 to 190°C. The relaxation ratio between the heating roller and the winder is preferably 0-2.0%. This is because, by controlling the tension during heat treatment within such a range, proper orientation and crystallization proceed, and the rigid amorphous content of the polyamide fiber can be controlled to 40% or more.

In addition, since the polyamide polymer coming out of the discharge hole under the die is slowly cooled, the cooling start distance is set to 30 to 170 mm, and the relaxation of the orientation is promoted, so that the rigid amorphous content can be further increased. More preferably, a heating cylinder is installed between the spinneret and the yarn cooling device, and the atmosphere temperature in the cylinder is set in the range of 100 to 300° C. to promote the relaxation of the orientation, thereby further increasing the rigid amorphous content. be able to.

The woven fabric of the present invention can be made into a woven fabric by weaving by a conventional method. The warp fibers are arranged on a creel, warped and wound on a beam, and then the fibers wound on the beam are starched and dried to prepare the warp. Next, the warp threads are passed through the reeds of the loom, and the weft threads are driven into the fabric. There are types of looms such as shuttle looms, air jet looms, water jet looms, rapier looms, and gripper shuttle looms, and any of these looms may be used. Depending on how the weft threads are woven, there are several types of weaving structures such as plain weave, twill, and satin weave, and any of them can be selected according to the purpose.

The knitted fabric of the present invention can be made into a knitted fabric by knitting by a conventional method. Knitting machines include flat knitting machines, circular knitting machines, and warp knitting machines, and any of them may be used for production. In addition, depending on the knitting, in the case of circular knitting and flat knitting, there are several knitting structures such as flat knitting, rib knitting, pearl knitting, interlock (double-sided knitting), and in the case of warp knitting, there are several knitting structures such as atlas structure, Denby structure, and cord structure. You can choose either one depending on your purpose.

Furthermore, the yarn used for the woven or knitted fabric must contain at least a portion of the polyamide fiber of the present invention. Other fibers are not particularly limited, such as natural fibers and chemical fibers.

Subsequently, dyeing processing is applied by a known method. Generally, it is finished by refining, intermediate setting, dyeing, and finish setting. Dyeing machines include jet dyeing machines, jigger dyeing machines, beam dyeing machines, wince dyeing machines, and the like. There are various types of polyamide dyes such as disperse dyes, acid dyes, complex salt dyes, acid mordant dyes, and reactive dyes. From the point of view, acid dyes and metal complex dyes can be preferably used, and the treatment is carried out at a temperature of 90° C. or higher for about 30 to 90 minutes. In addition, in order to prevent discoloration after dyeing, a fixing treatment with synthetic tannin, tannin/tartar emesis, etc. may be applied.

After dyeing, functional processing may be performed for the purpose of imparting functions. For example, in the case of a down jacket base fabric, calendering and water-repellent finishing are applied as functions. Calendering can be done on one or both sides and can be done at any stage of the dyeing process, but is preferably done after dyeing. For the water repellent treatment, a water repellent agent such as a paraffin-based, fluororesin-based, or silicone-based resin is used, and resin processing or the like is performed by padding, coating, dust absorption, lamination, or the like.

Polyamide fibers and woven or knitted fabrics of the present invention are not limited in their uses, but are used in sports, casual wear, women's and men's clothing such as windbreakers, down jackets, golf wear, rain wear, and inner wear. It can be used as various clothing products.

The present invention will be described in detail with examples. In addition, the following method was used for the measuring method in an Example.

A. Relative Viscosity of Sulfuric Acid 0.25 g of a sample was dissolved in 100 ml of sulfuric acid having a concentration of 98% by weight so as to give a concentration of 1 g. Subsequently, the flow-down time (T2) of sulfuric acid having a concentration of 98% by weight was measured. The ratio of T1 to T2, ie, T1/T2, was defined as the sulfuric acid relative viscosity.

B. Total fineness The total fineness was determined as the total fineness (dtex) by measuring the regular fineness with a predetermined load of 0.045 cN/dtex according to JIS L 1013 (2010) 8.3.1A method. Single fiber fineness (dtex) was obtained by dividing the total fineness by the number of filaments.

The sample was wound 200 times with a measuring machine with a frame circumference of 1.125 m to create a skein. The fineness was calculated from the obtained value. The measurement was performed 4 times, and the average value was used as the fineness. A single fiber fineness was obtained by dividing the obtained fineness by the number of filaments.

C. Strength and elongation Using "TENSILON" UCT-100 manufactured by Orientec Co., Ltd. as a measuring instrument, JIS L1013 (established in 1953, revised in 2010 (chemical fiber filament yarn test method)) was measured under constant speed elongation conditions. The elongation is obtained from the elongation at the point of maximum strength in the tensile strength-elongation curve.In addition, the strength is the value obtained by dividing the maximum strength by the fineness.The measurement was performed 10 times and the average was obtained. The values were taken as strength and elongation.

D. Rigid Amorphous Amount Rigid amorphous amount was measured using Q1000 manufactured by TA Instruments as a measuring instrument. The difference between the heat of fusion and the heat of cold crystallization (ΔHm−ΔHc) obtained from differential scanning calorimetry (hereinafter abbreviated as DSC) measurement, the specific heat difference (ΔCp) obtained from temperature-modulated DSC measurement, and further, the polyamide A theoretical value of 100% crystalline (completely crystalline) and a theoretical value of 100% amorphous (perfectly amorphous) polyamide are used. Here, ΔHm ⁰ is the heat of fusion of the polyamide (perfectly crystalline). ΔCp ⁰ is the specific heat difference around the glass transition temperature (Tg) of polyamide (perfectly amorphous).

Crystallinity (Xc) and mobile amorphous content (Xma) were obtained based on the formulas (1) and (2). Furthermore, the rigid amorphous content (Xra) was calculated from the formula (3). The rigid amorphous content was calculated from the average value of two measurements.
(1) Xc (%) = (ΔHm-ΔHc)/ΔHm ⁰ × 100
(2) Xma (%) = ΔCp/ΔCp ⁰ × 100
(3) Xra (%) = 100 - (Xc + Xma).

Measurement conditions for DSC and temperature-modulated DSC are shown below.

(DSC measurement)
Measuring device: TA Instruments Q1000
Data processing: TA Instruments Universal Analysis 2000
Atmosphere: Nitrogen flow (50 mL/min)
Sample amount: about 10 mg
Sample container: Aluminum standard container Temperature/calorie calibration: High-purity indium (Tm=156.61°C, ΔHm=28.71 J/g)
Temperature range: about -50 to 300°C
Heating rate: 10°C/min 1st heating process (first run)
(Temperature modulation DSC measurement)
Device: TA Instruments Q1000
Data processing: TA Instruments Universal Analysis 2000
Atmosphere: Nitrogen flow (50 mL/min)
Sample amount: about 5 mg
Sample container: Aluminum standard container Temperature/calorie calibration: High-purity indium (Tm=156.61°C, ΔHm=28.71 J/g)
Temperature range: about -50 to 210°C
Heating rate: 2°C/min
E. Accurately weigh 1 g of a polyamide chip or fiber sample that has undergone an amino end group amount drying treatment, dissolve it in 25 ml of a phenol/ethanol mixed solvent (83.5:16.5, volume ratio), and then dissolve it in a 0.02N hydrochloric acid aqueous solution. The amount of amino end groups was measured by titration during neutralization titration. In addition, the amino terminal group amount numerical value in this specification is represented by ×10 ⁻⁵ mol/g.

F. Titanium oxide content
The crucible is pre-fired in an electric furnace set to 800° C., cooled and then accurately weighed (A1). An absolutely dried sample is weighed into this crucible (S), and the sample is carbonized while being heated in an electric furnace. Samples are run on raw chips or fiber samples. Next, the crucible is baked in an electric furnace at 800° C. until it reaches a constant temperature, and cooled and accurately weighed (A2). From the results thus measured, the content of titanium oxide was determined by the method described below.
Titanium oxide content (%)=(A2-A1)/S×100.

G. Fabric preparation (Production of samples in the measurement of items H. and I.)
Using a tubular knitting machine NE450W manufactured by Eiko Sangyo Co., Ltd., a tubular knitted fabric was prepared by feeding two yarns. After scouring the obtained tubular knitted fabric, it is intermediately set under the conditions of 170° C.×1 minute, and dyed and fixed with a metal dye (lanasyn black M-DL 170 5%owf) under the conditions of 100° C.×30 minutes. After that, finish setting was performed under the conditions of 160° C.×1 minute.

H. Color developability The L value of the fabric obtained in the above section G was measured three times using a color meter SM-T manufactured by Suga Test Instruments Co., Ltd., and the L value was calculated from the average value. The L value relates to the lightness of an optical parameter, and the larger the L value, the whiter the color. In the evaluation of deep color development, the smaller the L value, the better.

The results of the L value were determined based on the range shown below, and C or higher was considered acceptable.

A: Less than 13 B: 13 or more to less than 16 C: 16 or more to less than 19 D: 19 or more.

I. Fastness The fabric obtained in Section G above was measured by A-2 method shown in JIS L0844 (testing fastness to washing), and color change and fading was graded. About the result judgment, grade 3 or higher was regarded as a pass.

(Example 1)
The polyamide was adjusted to have an amino terminal group content of 9.0×10 ⁻⁵ mol/g, and 175 kg of an 85% aqueous solution of ε-caprolactam, 460 g of hexamethylenediamine, and oxidized were placed in a polymerization reactor with a capacity of 200 liters. 12.5 kg of a 20% aqueous solution of titanium was charged and dissolved to form a uniform solution. After the inside of the polymerization reactor was sealed with nitrogen, the temperature was raised over 1 hour until the internal pressure of the reactor reached 0.98 MPa, and the temperature was continued to rise to 250°C while maintaining this pressure. After reaching 250° C., the pressure was released over 40 minutes until the atmospheric pressure was reached. After holding at 250° C. for 50 minutes at atmospheric pressure, the polymer was discharged and cooled/cut into pellets. Unreacted components in the pellets were extracted with 20 times the amount of hot water at 98°C relative to the pellets and dried in a vacuum dryer. The obtained polyamide chips had a sulfuric acid relative viscosity (abbreviated as ηr) of 2.6, an amino terminal group amount of 9.0×10 ⁻⁵ mol/g, and a titanium oxide content of 1.85% by weight.
The polyamide chips obtained as described above were melted at a spinning temperature of 260° C. and discharged from a spinneret having 68 round holes with a discharge hole diameter of 0.20 mm and a hole length of 0.50 mm. A heating cylinder with a length of 50 mm was placed between the spinneret and the yarn cooling device, and the cooling start distance was set to 169 mm. Cooled and solidified by blowing cold air with a cooling device, oiled with a lubricating device, entangled with a entangling nozzle device, drawn at a draw ratio of 2.1 times between a take-up roller and a drawing roller with a surface temperature of 155 ° C. The relaxation ratio between the drawing roller and the winder was set to 1.0%, and the fiber was wound with a winder at a winding speed of 4000 m/min to obtain a 44 dtex-34 filament polyamide fiber.
The obtained polyamide fiber was measured for strength, elongation, rigid amorphous content, amino terminal group content, and titanium oxide content, and evaluated for dyeability and fastness in a tubular knitted fabric. Table 1 shows the results.

(Example 2)
Polyamide chips were obtained in the same manner as in Example 1, except that the amount of hexamethylenediamine was adjusted so that the amount of amino end groups in the polyamide was 7.7 mol/g.

The polyamide chips obtained as described above and the polyamide fibers obtained under the same spinning conditions as in Example 1 were subjected to the same measurements and evaluations, and the results are shown in Table 1.

(Example 3)
Polyamide chips were obtained in the same manner as in Example 1, except that the amount of hexamethylenediamine and the polymerization time were adjusted so that the ηr of the polyamide was 3.3 and the amount of amino terminal groups was 7.9 mol/g.

Polyamide fibers obtained under the same spinning conditions as in Example 1, except that the polyamide chips obtained as described above had a draw ratio of 2.0 times and a relaxation rate of 1.6%, were subjected to the same measurements, Table 1 shows the evaluation results.

(Example 4)
Polyamide chips were obtained in the same manner as in Example 1, except that the amount of hexamethylenediamine was adjusted so that the amount of amino terminal groups in the polyamide was 7.0 mol/g.
Polyamide fibers obtained under the same spinning conditions as in Example 1, except that the polyamide chips obtained as described above had a draw ratio of 1.9 times and a relaxation rate of 0.8%, were subjected to the same measurements, Table 1 shows the evaluation results.

(Example 5)
Table 1 shows the results of the same measurements and evaluations performed under the same conditions as in Example 1, except that the relaxation rate was 1.5%.

(Example 6)
Table 1 shows the results of the same measurements and evaluations performed under the same conditions as in Example 1, except that the relaxation rate was 2.0%.

(Example 7)
Polycaproamide obtained by the same production method as in Example 1 except that the amount of titanium oxide added was adjusted so that the content of titanium oxide in the polyamide was 0.40% by weight, and the draw ratio was set to 1.8 times. Except for this, polyamide fibers obtained under the same spinning conditions as in Example 1 were subjected to the same measurements and evaluations, and the results are shown in Table 2.

(Example 8)
Polycaproamide obtained by the same production method as in Example 1 except that the amount of titanium oxide added was adjusted so that the content of titanium oxide in the polyamide was 5.00% by weight, and the draw ratio was set to 2.5 times. Except for this, polyamide fibers obtained under the same spinning conditions as in Example 1 were subjected to the same measurements and evaluations, and the results are shown in Table 2.

(Example 9)
Polycaproamide obtained by the same production method as in Example 1 except that the amount of titanium oxide added was adjusted so that the content of titanium oxide in the polyamide was 0.10% by weight, and the draw ratio was 1.7 times. Except for this, polyamide fibers obtained under the same spinning conditions as in Example 1 were subjected to the same measurements and evaluations, and the results are shown in Table 2.

(Example 10)
Polycaproamide obtained by the same production method as in Example 1 except that the amount of titanium oxide added was adjusted so that the content of titanium oxide in the polyamide was 9.00% by weight, and the draw ratio was set to 2.8 times. Except for this, polyamide fibers obtained under the same spinning conditions as in Example 1 were subjected to the same measurements and evaluations, and the results are shown in Table 2.

(Example 11)
A 200-liter polymerization reactor was charged with 300 kg of a 50% aqueous solution of an equimolar salt of adipic acid and hexamethylenediamine, 575 g of hexamethylenediamine, and 12.5 kg of a 20% aqueous solution of titanium oxide, and dissolved to form a uniform solution. . After sealing the inside of the polymerization reactor with nitrogen, the inner pressure of the reactor was maintained at 0.2 MPa, and the solution was concentrated until the water content in the solution reached 85 wt %. Thereafter, the temperature was raised over 1 hour until the internal pressure of the reactor reached 1.7 MPa, and the temperature was continued to rise to 255°C while maintaining this pressure. After reaching 255° C., the pressure was released to atmospheric pressure over 60 minutes. After that, the pressure in the can was reduced to -13 kPa and maintained for 30 minutes to complete the polycondensation reaction. The polymer was discharged, cooled/cut and pelletized. The resulting polyamide chip had an ηr of 2.7, an amino terminal group content of 9.0×10 ⁻⁵ mol/g, and a titanium oxide content of 1.85% by weight.
The polyamide fibers obtained under the same spinning conditions as in Example 1, except that the polyamide chips obtained as described above were melted at a spinning temperature of 290° C., were measured and evaluated in the same manner. 2.

(Comparative example 1)
Table 3 shows the results of the same measurements and evaluations performed under the same conditions as in Example 1, except that the draw ratio was 2.4 times and the relaxation rate was 3.0%.

(Comparative example 2)
It was obtained by the same production method as in Example 1, except that the amount of hexamethylenediamine was adjusted so that the amino terminal group amount of the polyamide was 5.1×10 ⁻⁵ mol/g. Polycaproamide was subjected to the same measurement and evaluation under the same conditions as in Example 1, and the results are shown in Table 3.

(Comparative Example 3)
Under the same conditions as in Example 1, except that the take-up roller speed was 4545 m/min, the draw ratio was 1.0 times, the draw roller was not heated, the relaxation rate was 1.0%, and the winding speed was 4500 m/min. Table 3 shows the results of similar measurements and evaluations.

(Comparative Example 4)
Polyamide chips were obtained in the same manner as in Example 1, except that the amount of hexamethylenediamine was adjusted so that the amount of amino end groups in the polyamide was 7.5×10 ⁻⁵ mol/gmol/g. Polycaproamide was processed under the same conditions as in Example 1 except that the take-up roller speed was 3550 m / min, the draw ratio was 1.3 times, the relaxation rate was 2.5%, and the winding speed was 4500 m / min. Table 3 shows the results of the measurement and evaluation of .

Since the polyamide fiber of the present invention has good color development and excellent fastness, it can be used for various clothing products such as sportswear, casual wear, women's and men's clothing, and innerwear.

Claims (5)

A polyamide fiber containing an aliphatic polyamide as a main component, wherein the amount of amino terminal groups in the aliphatic polyamide is 7.0×10 ⁻⁵ mol/g or more and 10.0×10 ⁻⁵ mol/g or less, and the polyamide A polyamide fiber having a rigid amorphous content of 40% or more required in the fiber. The polyamide fiber according to claim 1, containing 0.1 to 10.0% by weight of titanium oxide with respect to the total amount of the fiber. The polyamide fiber according to claim 1 or 2, having a total fineness of 5 to 235 dtex. A woven or knitted fabric for clothing comprising the polyamide fiber according to any one of claims 1 to 3. A method for producing a polyamide fiber, in which a polyamide resin raw material is melted, the polyamide resin is discharged from a nozzle, cooled and solidified to form a thread, the thread is drawn and heat-treated, and then wound,
The polyamide resin raw material contains an aliphatic polyamide, the amino terminal group amount in the aliphatic polyamide is 7.0 × 10 ^-5 mol / g or more and 10.0 × 10 ^-5 mol / g or less, and the following (a ) to (d), a method for producing a polyamide fiber.
(a) A discharge step in which the take-up speed is from 1300 m/min to 2400 m/min.
(b) A drawing step in which the yarn is drawn by the draft ratio of the take-up roller and the drawing roller, the temperature of the drawing roller is 150 to 190° C., and the draw ratio is 1.7 to 3.0 times.
(c) A relaxation treatment step in which the yarn is relaxed between the drawing roller and the winding roller after the drawing treatment, and the relaxation rate is 0 to 2.0%.
(d) A winding process at a winding speed of 3000 to 4500 m/min.