JP2023097202A - Thermoplastic polyurethane elastic fiber, wound yarn body containing the same, and sanitary material - Google Patents

Abstract

To provide a thermoplastic polyurethane elastic fiber having speed responsiveness, a wound yarn body containing the same, and a sanitary material.SOLUTION: Disclosed are: a thermoplastic polyurethane elastic fiber characterized by having a distance between hard domains measured by using a small angle x-ray scattering device of 10 nm or over and 30 nm or under and a half-value full width of an azimuth angle distribution peak of 50° or over and 130°or under; a wound yarn body comprising the thermoplastic polyurethane elastic fiber wound on a tube; and a sanitary material using the thermoplastic polyurethane elastic fiber.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a thermoplastic polyurethane elastic fiber and a wound body and sanitary material containing the same.

Conventionally, elastic gathers are arranged in the waist and legs of disposable diapers in order to prevent them from slipping when worn and to prevent leakage of urine and the like. Such gathers generally have a nonwoven fabric and elastic fibers such as rubber or polyurethane, and the elastic fibers are adhered to the nonwoven fabric with a hot-melt adhesive or the like in a stretched state during the production of the gathers, giving the gathers elasticity. Granted. In general, gathers of sanitary materials such as paper diapers are required to be resistant to slippage and to leave marks in addition to elasticity. Since elastic fibers have a great influence on these required performances, various proposals have been made for elastic fibers suitable for sanitary materials.
For example, Patent Literature 1 below discloses that a gather member that is easy to put on and take off and has a good fit can be obtained by controlling the specific stress during elongation of elastic fibers, stress retention rate, residual strain, and stress relaxation time. It is shown.

JP 2017-205433 A

By the way, it is desirable that sanitary materials such as paper diapers do not easily shift even when the wearer moves. In order to make the sanitary material less likely to leave marks and less likely to shift when the wearer moves, the gathers of the sanitary material should be generated when stretched at high speed compared to when stretched at low speed. It is desirable to have a performance (hereinafter also referred to as “speed responsiveness”) in which the applied stress becomes large. However, the gathers described in Patent Document 1 and the elastic fibers used therein do not have speed responsiveness. I couldn't say I could hold back.

SUMMARY OF THE INVENTION In view of the above problems of the prior art, an object of the present invention is to provide an elastic fiber having speed responsiveness, and a wound body and sanitary material containing the elastic fiber.

In order to solve the above problems, the inventors of the present application conducted extensive studies and repeated experiments, and found that the distance between hard domains measured by a small-angle X-ray scattering apparatus is 10 nm or more and 30 nm or less, and the full width at half maximum of the peak of the azimuth distribution. The present inventors have unexpectedly discovered that a thermoplastic polyurethane elastic fiber characterized by having an angle of curvature of 50° or more and 130° or less can solve the above problems, and have completed the present invention.
That is, the present invention is as follows.

[1] Thermal, characterized in that the distance between hard domains is 10 nm or more and 30 nm or less, and the full width at half maximum of the peak of the azimuthal distribution is 50° or more and 130° or less, as measured by a small-angle X-ray scattering apparatus. Plasticized polyurethane elastic fiber.
[2] The thermoplastic polyurethane elastic fiber according to [1], wherein the number of filaments is 10 or more and 160 or less.
[3] The thermoplastic polyurethane elastic fiber according to [1] or [2] above, which has a single filament fineness of 5 dtex or more and 30 dtex or less.
[4] The thermoplastic polyurethane elastic fiber according to any one of [1] to [3], which has a total fineness of 160 dtex or more and 1500 dtex or less.
[5] The thermoplastic polyurethane elastic fiber according to any one of [1] to [4] above, which contains polyurethane synthesized from polymer polyol, 4,4′-diphenylmethane diisocyanate, and 1,4-butanediol.
[6] The thermoplastic polyurethane elastic fiber according to any one of [1] to [5], wherein the hard segment has a molecular weight of 750 or more and 1500 or less.
[7] The thermoplastic polyurethane elastic fiber according to any one of [1] to [6], which is substantially free of crosslinks containing allophanate bonds.
[8] The thermoplastic according to any one of [1] to [7], which contains a treating agent in a content of 0.05% by mass or more and 5% by mass or less based on the mass of the thermoplastic polyurethane elastic fiber. Polyurethane elastic fiber.
[9] The thermoplastic polyurethane elastic fibers contain a treating agent, and the treating agent contains 10% by mass or more and 90% by mass or less of silicone oil with respect to the mass of the treating agent, [1] to The thermoplastic polyurethane elastic fiber according to any one of [8].
[10] Containing an ester or phosphate obtained by condensing compound A and compound B in an amount of 10 ppm or more and 1000 ppm or less with respect to the mass of the thermoplastic polyurethane elastic fiber, and the compound A having 4 or more and 30 or less carbon atoms Any one selected from the group consisting of monocarboxylic acids, dicarboxylic acids having 4 to 30 carbon atoms, tricarboxylic acids having 4 to 30 carbon atoms, and phosphoric acid, and the compound B has 1 to 30 carbon atoms The thermoplastic polyurethane elastic fiber according to any one of [1] to [9], which is any one selected from the group consisting of the following monools, diols having a molecular weight of 3000 or less, and triols having a molecular weight of 3000 or less.
[11] A wound body in which the thermoplastic polyurethane elastic fiber according to any one of [1] to [10] is wound around a tube, wherein the thermoplastic polyurethane elastic fiber is elongated in the wound body. A wound body having a rate of 0.1% or more and 10% or less.
[12] A sanitary material using the thermoplastic polyurethane elastic fiber according to any one of [1] to [10].

By controlling the distance between hard domains and the degree of orientation, the thermoplastic polyurethane elastic fiber of the present invention has rate responsiveness to elongation stress. It is hard to shift even when a person moves.

1 is an example of an apparatus for spinning thermoplastic polyurethane elastic fibers of the present embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. The present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of the gist of the present invention.

[Thermoplastic polyurethane elastic fiber]
The thermoplastic polyurethane elastic fiber of the present embodiment has a distance between hard domains of 10 nm or more and 30 nm or less as measured by a small-angle X-ray scattering apparatus (hereinafter also referred to as "SAXS") from the viewpoint of expressing speed responsiveness. Further, the full width at half maximum of the peak of the azimuth angle distribution is 50° or more and 130° or less. As an indicator of speed responsiveness, when using the ratio of 90% elongation stress at an elongation speed of 2000%/min to 90% elongation stress at an elongation speed of 2000%/min (hereinafter also referred to as "speed response ratio"), When the speed response ratio of the polyurethane elastic fiber is 1.05 or more and 3.00 or less, when it is used as a sanitary material, it is less likely to leave a mark when worn and less likely to shift when the wearer moves. is obtained.

The reason why a thermoplastic polyurethane elastic fiber having an inter-hard domain distance measured by SAXS of 10 nm or more and 30 nm or less and a peak full width at half maximum of an azimuth angle distribution of 50° or more and 130° or less exhibiting velocity responsiveness is the reason. It is not clear yet, but we speculate as follows:
When a thermoplastic polyurethane elastic fiber with a long distance between hard domains, i.e., a large hard domain size, is stretched at high speed, the structure of the hard domain of the polyurethane elastic fiber is greatly destroyed compared to when it is stretched at a low speed. Because the physical properties are improved by the breaking stress, speed responsiveness is expressed;
When a thermoplastic polyurethane elastic fiber with a degree of orientation in which the full width at half maximum of the peak of the azimuthal distribution is 50° or more is stretched at a high speed, the structure of the hard domain of the polyurethane elastic fiber is greatly destroyed compared to when it is stretched at a low speed. The physical properties are improved by the breaking stress, and the speed responsiveness is increased;
Thermoplastic polyurethane elastic fibers with a degree of orientation in which the full width at half maximum is 130° or less show little change in the structure of the hard domain when stretched at a low speed, and there is a difference in structural change when stretched at a relatively high speed. becomes larger, and the speed responsiveness becomes larger.

The distance between the hard domains is preferably 10 nm or more and 27 nm or less, more preferably 10 nm or more and 25 nm or less, even more preferably 10.5 nm or more and 20 nm or less, most preferably 11 nm or more and 15 nm or less, and The full width at half maximum is preferably 60° or more and 110° or less, more preferably 70° or more and 90° or less, and most preferably 75° or more and 80° or less.

The thermoplastic polyurethane elastic fiber of the present embodiment preferably contains 80 wt% or more, more preferably 85 wt% or more, even more preferably 90 wt% or more, and most preferably 95 wt% or more of thermoplastic polyurethane. The thermoplastic polyurethane is not particularly limited as long as it has thermoplasticity, for example, as long as it has a structure polymerized from diisocyanate, polymer polyol, low-molecular-weight diol, low-molecular-weight diamine, or the like. do not have. Also, the polymerization method is not particularly limited. The thermoplastic polyurethane may be, for example, a polyurethane polymerized from a diisocyanate, a polymer polyol, and a low-molecular-weight diamine as a chain extender composed of an active hydrogen compound (hereinafter also referred to as "polyurethane urea"). Polyurethane (hereinafter also referred to as "polyurethane urethane") polymerized from a low-molecular-weight diol as a chain extender composed of diisocyanate, polymer polyol, and active hydrogen compound may also be used. Tri- or higher functional glycols and isocyanates may be used as long as they do not interfere with the desired effects of the present invention. In this specification, the term “thermoplastic” means that it can be melted by heating at a decomposition temperature or lower, exhibits plastic flow while in a molten state, and has a reversible property of solidifying upon cooling. means Polyurethane resin generally begins to decompose at 230° C. or higher.

Polymer polyols include, but are not limited to, polymer diols such as polyether-based diols, polyester-based diols, and polycarbonate diols. From the viewpoint of hydrolysis resistance, the polymer polyol is preferably a polyether-based polyol, more preferably a polyether-based diol.

Polyether-based polyols include, for example, polyethylene oxide, polyethylene glycol, polyethylene glycol derivatives, polypropylene glycol, polytetramethylene ether glycol, copolymerized diols composed of tetrahydrofuran (THF) and neopentyl glycol, and THF and 3-methyltetrahydrofuran. Copolymer diols are mentioned. One of these polyether-based polyols may be used alone, or two or more thereof may be used in combination. Moreover, the polymer diol preferably has a number average molecular weight of 1,000 or more and 8,000 or less. By using a polymer diol within this range, an elastic fiber excellent in elongation, stretch recovery and heat resistance can be easily obtained. From the viewpoint of speed responsiveness and light embrittlement, the polyether-based polyol should be polytetramethylene ether glycol, a copolymerized diol that is a copolymer of THF and neopentyl glycol, or a blended polyol of these. is preferred.

Diisocyanates include, for example, aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates. Examples of the aromatic diisocyanate include, but are not limited to, diphenylmethane diisocyanate (hereinafter also referred to as "MDI"), tolylene diisocyanate, 1,4-diisocyanatobenzene, xylylene diisocyanate, 2,6-naphthalene diisocyanate, and the like. mentioned. Examples of alicyclic diisocyanates and aliphatic diisocyanates include methylene bis(cyclohexyl isocyanate) (hereinafter also referred to as "H12MDI"), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, octahydro-1,5-naphthalene diisocyanate and the like. These diisocyanates may be used alone or in combination of two or more. From the viewpoint of speed responsiveness and stretch recovery of elastic fibers, the diisocyanate is preferably an aromatic diisocyanate, more preferably MDI.

The chain extender comprising an active hydrogen compound is preferably at least one selected from the group consisting of low molecular weight diamines and low molecular weight diols. The chain extender may have both a hydroxyl group and an amino group in its molecule, such as ethanolamine. From the viewpoint of obtaining a thermoplastic polyurethane suitable for melt spinning, the active hydrogen compound is preferably a low molecular weight diol.

Examples of low-molecular-weight diamines as chain extenders composed of active hydrogen compounds include, but are not limited to, hydrazine, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methyl-1,5- pentanediamine, 1,2-diaminobutane, 1,3-diaminobutane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,2-dimethyl-1,3-diaminopropane, 1, 3-diamino-2,2-dimethylbutane, 2,4-diamino-1-methylcyclohexane, 1,3-pentanediamine, 1,3-cyclohexanediamine, bis(4-aminophenyl)phosphine oxide, hexamethylenediamine, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, bis(4-aminophenyl)phosphine oxide and the like.

Examples of low-molecular-weight diols as chain extenders composed of active hydrogen compounds include, but are not limited to, ethylene glycol, 1,3-propanediol, 1,4-butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, 1 -methyl-1,2-ethanediol, 1,6-hexanediol and the like. One of these low-molecular-weight diols may be used alone, or two or more thereof may be used in combination. From the viewpoint of speed responsiveness and stretch recovery of elastic fibers, the low-molecular-weight diol is preferably a diol having a molecular weight of 60 or more and 120 or less, more preferably 1,4-butanediol.

The thermoplastic polyurethane can be produced by any of the one-shot method and the prepolymer method, using a known polyurethane reaction technique. In the case of the prepolymer method, the polymer polyol and the diisocyanate are placed in a reaction tank equipped with a hot water jacket and an agitator under a nitrogen purge in a molar ratio of preferably 1.0:1.8 to 3.0, more preferably 1.0. : 2.0 to 2.5, and the prepolymer reaction is preferably carried out at 40°C or higher and 100°C or lower, more preferably 50°C or higher and 80°C or lower, to obtain a prepolymer with isocyanate groups at both ends. Next, an active hydrogen compound is added to the isocyanate group prepolymer at both ends in an equivalent amount approximately equal to the number of functional groups of the isocyanate terminal groups to carry out a chain extension reaction. The equivalent ratio is preferably 0.95 or more and 1.1 or less, more preferably 0.99 or more and 1.05 or less with respect to the isocyanate terminal group. After that, solid phase polymerization can be performed to obtain a polyurethane having a predetermined molecular weight. As a method for chain extension reaction and solid phase polymerization, an active hydrogen compound is added to a batch reaction vessel containing a prepolymer at a temperature of preferably 40° C. or higher and 100° C. or lower as it is, and then discharged and solid phase polymerization is preferably performed at 60° C. 200° C. or higher, more preferably 70° C. or higher and 150° C. or lower, and pelletized to obtain polymer chips. After uniformly mixing the prepolymer and the active hydrogen compound, the cylinder temperature in the polymerization zone is preferably 160° C. or higher and 240° C. or lower using a cylindrical pipe or a twin-screw extruder, and the polymer is continuously or semi-continuously extruded. After obtaining, solid phase polymerization may be carried out at preferably 60°C to 220°C, more preferably 70°C to 150°C.

The spinning method for producing the thermoplastic polyurethane elastic fiber is not particularly limited as long as the desired physical properties are obtained. For example, a method of putting thermoplastic polyurethane chips into an extruder, heating them, and melt spinning, a method of melting polyurethane elastic chips and then mixing them with a polyisocyanate compound for spinning, and a method of mixing and spinning a polyisocyanate compound at both ends, A method of adding a reactant of a prepolymer with isocyanate groups at both ends and an active hydrogen compound and continuously spinning without going through chipping may be mentioned.

When thermoplastic polyurethane chips are fed into an extruder, heated and melt-spun, the thermoplastic polyurethane chips fed into the extruder are metered by a metering pump and introduced into the spinning head. If necessary, foreign matter is removed by filtration using a wire mesh or glass beads in the spinning head, then the product is discharged from the spinneret, cooled in a cold air chamber, treated with a treatment agent as necessary, and then a godet roll. is taken up via

In the spinning process, it is preferable to control the temperature profile of the fiber and the spinning tension by adjusting the spinneret temperature, cold air speed, cold air temperature, convergence position and spinning speed. The temperature of the die is preferably 180°C to 220°C, more preferably 200°C to 210°C. Regarding the cooling method, from the viewpoint of controlling the distance and orientation between the hard domains, cold air is not applied directly below the nozzle, the temperature of the cold air is gradually cooled with a gradient, the length of the cold air chamber is lengthened, and the nozzle and the focusing position are used. It is preferable to cool by combining a method such as lengthening the distance of . A common cooling method for melt spinning can be used, such as applying cold air perpendicularly to the running direction of the yarn. It is more preferably 0.5 m/s to 1.2 m/s, and the temperature of the cool air is preferably 5°C to 20°C, more preferably 7°C to 15°C. As a method for bundling the multifilament, there is a method in which a false twister is installed between the spinneret and the godet rolls to perform false twisting. At this time, by controlling the strength of the twist, the twist can be propagated above the false twister and the height of the convergence point can be controlled. A general method of false twisting can be selected, and air false twisting using an air nozzle, a ring false twisting machine in contact with a rotating ring, or the like can be used.

The thermoplastic polyurethane elastic fibers may be coated with a treatment agent such as an oil from the viewpoint of unwindability, processability, and the like. Treatment agents include, for example, silicone oils such as dimethyl silicone, mineral oils, higher alcohols, and combinations thereof. Treatment agents such as these oils include talc, silica, mineral fine particles such as colloidal alumina, powders of higher fatty acid metal salts such as magnesium stearate and calcium stearate, higher fatty acid carboxylic acids, higher aliphatic alcohols, paraffin polyethylene and the like. Various materials such as solid waxes may also be included.

From the viewpoint of speed responsiveness, the thermoplastic polyurethane elastic fiber preferably contains a processing agent such as an oil in an amount of 0.05% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 2% by mass or less, based on the yarn mass. include. From the viewpoint of speed responsiveness, the treatment agent preferably contains 10% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 85% by mass or less of silicone oil. Examples of silicone oils include modified silicone oils such as dimethylsilicone, polyether-modified silicone, polyamino-modified silicone, phenyl-modified silicone and alkyl-modified silicone. The method of applying the treatment agent is not particularly limited, and examples thereof include a method of applying with an oiling roller or the like and a method of applying with a nozzle.

From the viewpoint of speed responsiveness, the thermoplastic polyurethane elastic fiber is obtained by adding an ester or a phosphoric acid ester obtained by condensing a compound A, which is a carboxylic acid or a phosphoric acid, and a compound B, which is an alcohol, to the mass of the thermoplastic polyurethane elastic fiber. On the other hand, it is preferably contained so as to be 10 ppm or more and 1000 ppm or less, preferably 30 ppm or more and 500 ppm or less, more preferably 50 ppm or more and 300 ppm or less. Compound A is any one selected from the group consisting of monocarboxylic acids having 4 to 30 carbon atoms, dicarboxylic acids having 4 to 30 carbon atoms, tricarboxylic acids having 4 to 30 carbon atoms, and phosphoric acid. and the compound B is any one selected from the group consisting of monools having 1 to 30 carbon atoms, diols having a molecular weight of 3,000 or less, and triols having a molecular weight of 3,000 or less. The ester or phosphate ester is, for example, contained in a treatment agent and applied to the polyurethane elastic fiber.

Regarding the compound A, there are no particular restrictions on the presence or absence of branching or substituents. Compound A may have any other bond or substituent as long as it has a monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid structure. It may have a bond such as a urethane bond, or a group such as an epoxy group, a nitro group, a cyano group, a ketone group, a formyl group, an acetal group, a thioacetal group, a sulfonyl group, or the like. Examples of monocarboxylic acids having 4 to 30 carbon atoms, dicarboxylic acids having 4 to 30 carbon atoms, and tricarboxylic acids having 4 to 30 carbon atoms include benzoic acid, phthalic acid, terephthalic acid, trimellitic acid, and adipic acid. , sebacic acid, azelaic acid, maleic acid, citric acid, lauric acid, myristic acid, stearic acid, oleic acid, and epoxidized vegetable oils.

Regarding compound B, there are no particular restrictions on the presence or absence of branching or substituents. Compound B may have any other bond or substituent as long as it has a monool, diol, or triol structure, such as ester bond, amide bond, ether bond, sulfide bond, disulfide bond, urethane bond, or a group such as an epoxy group, a nitro group, a cyano group, a ketone group, a formyl group, an acetal group, a thioacetal group, a sulfonyl group, or the like. Examples of compound B include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-hexanol, 2-hexanol, 3-hexanol, cyclohexyl alcohol, 2-ethyl-1-hexanol, 1-nonanol, isodecyl alcohol, phenol, monools such as benzyl alcohol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butane Diols such as diols, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol and polypropylene glycol, triols such as glycerin and 1,2,4-butanetriol etc.

In the present embodiment, from the viewpoint of effectively exhibiting speed responsiveness, compound A includes a monocarboxylic acid having 4 to 30 carbon atoms, a dicarboxylic acid having 4 to 30 carbon atoms, and a tricarboxylic acid having 4 to 30 carbon atoms. Any one of the acids is preferred.

In the present embodiment, from the viewpoint of more effectively exhibiting speed responsiveness, compound A includes a monocarboxylic acid containing an aromatic ring and having 4 to 30 carbon atoms, a dicarboxylic acid having 4 to 30 carbon atoms, and a dicarboxylic acid having 4 or more carbon atoms. It is preferably a tricarboxylic acid having 30 or less, most preferably a monocarboxylic acid having 4 to 15 carbon atoms containing an aromatic ring, a dicarboxylic acid having 4 to 15 carbon atoms and a tricarboxylic acid having 4 to 15 carbon atoms. Preferred examples include benzoic acid, phthalic acid, terephthalic acid, and trimellitic acid.

In the present embodiment, from the viewpoint of effectively suppressing speed responsiveness, compound B is more preferably a monool having a carbon number of 15 or less, a diol having a molecular weight of 1500 or less, or a triol having a molecular weight of 1500 or less. It is more preferably a monool having a molecular weight of 500 or less, or a triol having a molecular weight of 500 or less, more preferably a monool having a carbon number of 15 or less, or a diol having a molecular weight of 500 or less. Diols are most preferred. Diols having a molecular weight of 500 or less include ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol.

Thermoplastic polyurethane elastic fibers may contain polymers other than polyurethane and additives such as antioxidants, light stabilizers, ultraviolet absorbers, gas discoloration inhibitors, dyes, activators, etc., as long as the desired effects are not lost. Matting agents, lubricants, etc. may be contained.

The number of filaments of the thermoplastic polyurethane elastic fiber is preferably 10 or more and 160 or less, more preferably 15 or more and 140 or less, still more preferably 20 or more and 120 or less, from the viewpoint of speed responsiveness. Although it is not clear why the speed response ratio can be increased by setting the number of filaments to 10 or more and 160 or less, the inventors presume as follows. A thermoplastic polyurethane elastic fiber manufactured so that the number of filaments is 10 or more has high physical properties of the raw yarn, so that the speed response ratio of the raw yarn can be easily reflected in the gather. The thermoplastic polyurethane elastic fiber manufactured so that the number of filaments is 160 or less can uniformly cool the single yarns during the cooling process in the melt spinning process, so the variation in physical properties between single yarns can be reduced, and the speed responsiveness is improved. easier to manifest.

The single filament fineness of the thermoplastic polyurethane elastic fiber is preferably 5 dtex or more and 30 dtex or less, more preferably 6 dtex or more and 25 dtex or less, still more preferably 7 dtex or more and 20 dtex or less, from the viewpoint of speed response. Although it is not clear why the speed response ratio can be increased by setting the single yarn fineness to 5 dtex or more and 30 dtex or less, the inventors presume as follows. Thermoplastic polyurethane elastic fibers produced to have a single filament fineness of 5 dtex or more have uniform cooling between single filaments during the cooling process in the melt spinning process, so variations in physical properties between single filaments are reduced, and speed increases. It becomes easy to express responsiveness. The thermoplastic polyurethane elastic fiber manufactured so that the single yarn fineness is 30 dtex or less is easy to cool in the cooling process in the melt spinning process, the physical property variation between single yarns can be reduced, and the raw yarn has speed responsiveness. It becomes easy to express it, and it becomes easy to reflect the speed response ratio of the raw yarn on the gather.

The total fineness of the thermoplastic polyurethane elastic fibers is preferably 160 dtex or more and 1500 dtex or less, and 300 dtex or more and 1300 dtex or less, from the viewpoint of speed responsiveness. Although it is not clear why the speed response ratio can be increased by setting the total fineness of the thermoplastic polyurethane elastic fibers to 160 dtex or more and 1500 dtex, the inventors presume as follows. A thermoplastic polyurethane elastic fiber manufactured so as to have a total fineness of 160 dtex or more has high physical properties of the raw yarn, so that the speed response ratio of the raw yarn can be easily reflected in the gather. Thermoplastic polyurethane elastic fibers produced to have a total fineness of 1500 dtex or less are uniformly cooled during the cooling process in the melt spinning process, so that variations in physical properties in the fiber length direction are reduced and speed responsiveness is exhibited. easier.

The thermoplastic polyurethane elastic fiber preferably contains polyurethane synthesized from polymer polyol, MDI, and 1,4-butanediol from the viewpoint of exhibiting speed responsiveness. Although it is not clear why the thermoplastic polyurethane elastic fiber contains polyurethane synthesized from polymer polyol, MDI, and 1,4-butanediol, it is possible to exhibit speed responsiveness, but the inventors are as follows. is estimated to be Thermoplastic polyurethane elastic fibers synthesized from polymer polyol, MDI, and 1,4-butanediol have strong hydrogen-bonding strength in the hard domains, and the structure of the hard domains is greatly destroyed when stretched at high speed. When stretched, the structure of the hard domain is less likely to be destroyed, and the speed response ratio can be increased.

The molecular weight of the hard segment of the thermoplastic polyurethane elastic fiber is preferably 750 or more and 1500 or less, more preferably 800 or more and 1300 or less, still more preferably 850 or more and 1200 or less, from the viewpoint of expressing speed responsiveness. By setting the molecular weight of the hard segment of the thermoplastic polyurethane elastic fiber of the present embodiment to 750 or more and 1500 or less, the speed response ratio can be easily made 1.05 or more and 3.00 or less. Although it is not clear why the speed response ratio is easily made 1.05 or more and 3.00 or less by setting the molecular weight of the hard segment to 750 or more and 1500 or less, the inventors presume as follows. . When the molecular weight of the hard segment is 750 or more and 1500 or less, when the gather containing the thermoplastic polyurethane elastic fiber is stretched at high speed, the degree of structural destruction of the hard domain of the polyurethane elastic fiber is moderate, and the speed response ratio is is controlled within the range of 1.05 to 3.00. The method for producing the thermoplastic polyurethane elastic fiber in which the hard segment has a molecular weight of 750 or more and 1500 or less is not particularly limited. A manufacturing method is preferably used. In general, the higher the number of moles of isocyanate to polymer polyol, the higher the molecular weight of the hard segment.

From the viewpoint of speed responsiveness, the thermoplastic polyurethane elastic fiber preferably does not substantially have crosslinks containing allophanate bonds in which urethane bonds are crosslinked by isocyanate groups. Although the reason why the rate response ratio is increased by not having a crosslink containing an allophanate bond is not clear, it is presumed as follows. When a thermoplastic polyurethane elastic fiber that does not contain a cross-linked structure is stretched at high speed, the structure of the hard domain is likely to be destroyed when stretched at high speed, resulting in a high velocity response ratio and a deviation of gathers when the wearer moves. Difficulty is demonstrated. The method for producing thermoplastic polyurethane elastic fibers having no crosslinks containing allophanate bonds is not particularly limited, but for example, the total number of moles of the chain extender comprising the polymer polyol and the active hydrogen compound is equal to or greater than the number of moles of isocyanate. A method of producing thermoplastic polyurethane elastic fibers from controlled polymerized thermoplastic polyurethane is preferably used.

From the viewpoint of effectively exhibiting speed responsiveness, the thermoplastic polyurethane elastic fiber preferably has an elongation rate of 0.1% or more in the state of a wound yarn wound around a tube such as a paper tube. It is preferably 10% or less, more preferably 5% or less, and most preferably 3% or less. Generally, thermoplastic polyurethane elastic fibers are wound around a paper tube in a state of being stretched rather than in a relaxed state to form a wound body. In this state of the wound body, the rate at which the polyurethane elastic fibers are elongated with respect to the relaxed state is called the elongation rate in the wound body. By setting the elongation rate of the polyurethane elastic fiber in the wound body to 0.1% or more and 10% or less, it is possible to suppress an increase in the degree of orientation over time and maintain the speed responsiveness of the yarn. I'm assuming it can. The method for setting the elongation rate to 0.1% or more and 10% or less is not particularly limited, but for example, there is a method of adjusting the speed ratio between the godded roller and the winding roller when the polyurethane elastic fiber is wound.

[Hygiene materials]
A sanitary material comprising a wound body of the thermoplastic polyurethane elastic fiber of the present embodiment and a gather containing the thermoplastic polyurethane elastic fiber is also an aspect of the present invention. Specific examples of sanitary materials include absorbent articles such as disposable diapers and sanitary products. In disposable diapers, the thermoplastic polyurethane elastic fibers of the present embodiment are preferably used for waist portions and leg portions.

EXAMPLES The present invention will be specifically described with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the examples.
First, evaluation methods used in the following examples will be described.

(1) Distance between Hard Domains of Thermoplastic Polyurethane Elastic Fiber and Full Width at Half Maximum of Peak of Azimuth Distribution A thermoplastic polyurethane elastic fiber was set on a sample stage so that the fiber axis was horizontal. The fibers were irradiated with X-rays perpendicularly and measured using SAXS under the following conditions.
Measuring device: NANOPIX manufactured by Rigaku Corporation
Incident X-ray wavelength λ: 0.154 nm
Detector: Two-dimensional detector "Hypix-6000"
Measurement time: 15 minutes Camera length: 1312mm
Optical system:
Point collimation:
1st slit: 0.55 mmφ, guard slit: 0.35 mmφ
High Resolution Mode
Beam stopper: 2mmφ

｛式中、φ_ｓ：－１０°、φ_ｅ：１０°、θ：ブラッグ角。｝により、扇型状の平均散乱強度Ｉを計算した。
得られた扇型状平均の散乱強度Ｉを下式：

｛式中、I _c(２θ)：空セル補正済みの散乱強度、I _sample(２θ)：サンプルの散乱強度、I _empty(２θ)：空セルの散乱強度、t _sample：サンプルの測定時間、t _empty：空セル測定の測定時間、T：透過率、C：装置定数｝により、空セル散乱補正を行い、１次元散乱強度Ｉ_cを算出した。 With the 12 o'clock direction of the two-dimensional SAXS pattern I (2θ, φ) obtained by the two-dimensional detector as 0°, the azimuth angle θ is defined clockwise, and the following formula:

{wherein φ _s : −10°, φ _e : 10°, θ: Bragg angle. }, the fan-shaped average scattering intensity I was calculated.
The obtained fan-shaped average scattering intensity I is expressed by the following formula:

{In the formula, I _c (2θ): empty cell corrected scattering intensity, I _sample (2θ): sample scattering intensity, I _empty (2θ): empty cell scattering intensity, t _sample : sample measurement time, t _empty : measurement time for empty cell measurement, T: transmittance, C: apparatus constant}, empty cell scattering correction was performed, and the one-dimensional scattering intensity I _c was calculated.

｛式中、θ：ブラッグ角、λ：入射Ｘ線波長｝。 Next, the distance between hard domains was calculated from the peak position _qmax obtained by fitting the vicinity of the peak of the one-dimensional scattering intensity _Ic with a Gaussian function. Note that q is the absolute value of the scattering vector.

{wherein θ: Bragg angle, λ: incident X-ray wavelength}.

｛式中、I _sample(q, φ)：サンプルの２次元散乱パターン、I _empty(q, φ)：空セルの２次元散乱パターン｝により計算した。 Subsequently, the azimuth angle distribution of the scattered light intensity at q _s <q<q _e (q _s =q _max −0.1 nm ⁻¹ ,q _e =q _max +0.1 nm ⁻¹ ) is expressed by the following formula:

{wherein, I _sample (q, φ): sample two-dimensional scattering pattern, I _empty (q, φ): empty cell two-dimensional scattering pattern}.

により規格化した。 The obtained azimuth angle distribution I(φ) is expressed by the following formula:

normalized by

From the peak observed in the normalized azimuth angle distribution I _N (φ), the full width at half maximum was calculated under the following conditions.
Analysis software: Wavemetrics Igor Pro 8.00
Fitting method: Igor Pro 8.00 Multi-peak Fit
A constant connecting both ends of the tail of the peak was used as an initial value for the baseline, and the value was used as a variable. A Gaussian function was used as the fitting function, and the Location, Width, and Height of the peak in Multi-peak Fit were used as variables, and their initial values were set to 90°, 50°, and 1, respectively.

(2) Number of filaments of elastic fiber>
The cross section of the thermoplastic polyurethane elastic fiber was observed using an electron microscope JSM-6510 manufactured by JEOL Ltd., and the number of single yarns was measured as the number of filaments.

(3) Total Fineness of Elastic Fibers The length of the thermoplastic polyurethane elastic fibers in a relaxed state (hereinafter also referred to as "relaxed length") and the mass (g) of the sample were measured. The total fineness (dtex) of the thermoplastic polyurethane elastic fiber in the relaxed state was calculated from the following formula. The measurement was performed 4 times and the average value was taken. The "relaxed state" refers to a state in which the thermoplastic polyurethane elastic fibers taken out from the gathers are left unloaded for 2 hours or more.
Total fineness A (dtex) = sample weight (g) x 10000/relaxed length (m)

(4) Single filament fineness of thermoplastic polyurethane elastic fiber Using the total fineness (dtex) and the number of filaments obtained in (2) and (3) above, the following calculation formula:
The single yarn fineness (dtex) of the thermoplastic polyurethane elastic fiber was calculated from single yarn fineness (dtex)=total fineness (dtex)/number of filaments.

(5) Qualitative determination of constituent components of thermoplastic polyurethane and measurement of molecular weight of hard segment A sample taken from the thermoplastic polyurethane elastic fiber and a predetermined amount of dimethyl sulfoxide as an internal standard are weighed and NMR is measured under the following conditions to obtain a polymer polyol. , chain extender, and diisocyanate structures and molar ratios were identified. The structures of the diisocyanate and the chain extender can be judged from the peak positions by NMR measurement.
Measuring device: Bruker Biospin Avance600
Measurement nucleus: 1H
Resonance frequency: 600MHz
Accumulation times: 256 Measurement temperature: Room temperature Solvent: Deuterated dimethylformamide Measurement concentration: 1.5% by mass
Chemical shift reference: dimethylformamide (8.0233 ppm)

The molecular weight of the hard segment of the thermoplastic polyurethane elastic fiber is calculated by solving the following simultaneous equations (1) and (2).
Mh = {Mda (N1-1) + Mdi × N0} / (N1-N0-1) + 2Mdi ... formula (1)
N0=0.03806N1 ⁴ −0.03997N1 ³ +1.617N1 ² −2.144N ¹ +0.8795 Formula (2)
Mda: Molecular weight of the chain extender (number average molecular weight when using a mixture of two or more types)
Mdi: molecular weight of isocyanate N0: molar ratio of unreacted isocyanate to polymer polyol N1: molar ratio of isocyanate to polymer polyol Mh: molecular weight of hard segment

(6) Determining the presence or absence of cross-linking containing allophanate bonds in thermoplastic polyurethane elastic fibers A thermoplastic polyurethane elastic fiber that dissolves in the following DMAc dissolution test and in which allophanate bonds cannot be confirmed by the following NMR measurement is defined as the term used in this specification. It was judged as having "no cross-links containing allophanate bonds". A thermoplastic polyurethane elastic fiber that did not dissolve in the DMAc dissolution test described below, or dissolved in the DMAc dissolution test described below but confirmed allophanate bonds in the NMR measurement described below was judged to have "crosslinks containing allophanate bonds.
<DMAc dissolution test>
0.2 g of thermoplastic polyurethane elastic fiber is weighed out precisely, immersed in 10 g of DMAc, and stirred at 20° C. for 48 hours. After agitation, when no bulk polymer with a diameter of 1 mm or more was visually observed, it was determined that the polymer was dissolved in DMAc.
<NMR measurement (qualification of allophanate binding)>
Predetermined amounts of polyurethane elastic fibers and internal standard dimethyl sulfoxide dried at -0.1 MPa at 80°C for 5 hours were measured and NMR was measured under the following conditions. This measurement confirmed the ratio of allophanate linkages to urethane linkages. The ratio of allophanate bonds to the urethane bonds can be calculated by comparing the integrated values of the respective hydrogens, and when this ratio is less than 0.05%, it is defined that no allophanate groups are contained. In general, hydrogen signals of allophanate bonds are often observed at 10.5 to 11.0 ppm, but this is not the only option.
[NMR measurement conditions]
Measuring device: ECS400 manufactured by JEOL
Measurement nucleus: ^1H
Resonance frequency: 400MHz
Accumulation times: 256 Measurement temperature: Room temperature Solvent: Deuterated dimethylformamide Measurement concentration: 1.5% by mass
Chemical shift reference: dimethylformamide (8.0233 ppm)

(7) Content of treatment agent The content of the treatment agent was calculated by removing the treatment agent from the thermoplastic polyurethane elastic fiber with petroleum ether and measuring the mass before and after drying. Specifically, first, about 5 g of thermoplastic polyurethane elastic fiber was accurately weighed, and the mass (Wa [g]) before removal of the treating agent was obtained. The accurately weighed yarn was placed in a container containing 50 ml of petroleum ether and subjected to ultrasonic waves for 5 minutes. After discarding the petroleum ether in the container, 50 ml of petroleum ether was added again and ultrasonic waves were applied for 5 minutes. After the completion, the petroleum ether in the container was removed, dried in an oven at 50° C. for 3 hours, and the mass after drying (Wb [g]) was accurately weighed. From the obtained masses, the content of the treatment agent was calculated according to the following formula.

(8) Measurement of Ester or Phosphate Amount 1 g of elastic polyurethane fiber is subjected to Soxhlet extraction with 120 mL of chloroform for 8 hours. This extract is concentrated to dryness in an evaporator at 40° C., and vacuum-dried at room temperature for 1 hour to obtain a dried sample, which is analyzed by known methods such as GC/MS and NMR. The details of the analysis conditions are as follows.

<NMR measurement>
Predetermined amounts of the dried sample and dimethyl sulfoxide as an internal standard were measured and NMR was measured under the following conditions to identify the structure of the ester or phosphate and calculate the content. The content of the ester or phosphate was calculated from the integral value of the hydrogen signal with dimethylsulfoxide as an internal standard. For example, when calculating the content of diethylene glycol benzoate, it can be calculated by comparing the integrated value of hydrogen of the phenyl group of diethylene glycol benzoate and the integrated value of hydrogen of the methyl group of dimethylsulfoxide. When the content could not be measured by NMR measurement due to overlap of peaks, etc., the content was measured by the following GC/MS analytical measurement.
Measuring device: ECS400 manufactured by JEOL
Measurement nuclei: 1H
Resonance frequency: 400MHz
Accumulation times: 256 Measurement temperature: Room temperature Solvent: Deuterated dimethylformamide Measurement concentration: 1.5% by mass
Chemical shift reference: dimethylformamide (8.0233 ppm)

<GC/MS analysis measurement>
The dry sample is dissolved in 5 mL of methanol and analyzed. The concentration of the ester or phosphate ester is determined by separately preparing a calibration curve for the ester or phosphate ester whose structure has been identified by NMR measurement using GC, and comparing it with the area of the ester or phosphate ester in the dry sample. Mass% was calculated by doing.
GC apparatus: Agilent Technologies 7890A
Inlet temperature: 320°C
Column: DB-1MS (30 m × 0.25 mmφ), liquid phase thickness 0.25 μm
Column temperature: 40°C (holding time 5 minutes), temperature rise of 20°C/min, 320°C (holding for 11 minutes)
MS equipment: Agilent Technologies 5975C MSD
Ion source temperature: 230°C
Ionization method: electron ionization method

(9) Measurement of the amount of silicone contained in the treatment agent The amount of silicone contained in the treatment agent is the amount of silicone measured by the same method as the measurement of the amount of ester or phosphate described in (8) above, and the amount of silicone ( It was obtained from the content of the treating agent measured in 7).

(10) Elongation rate of polyurethane elastic fiber in wound body The elongation rate (%) of the polyurethane elastic fiber in the wound body was measured by the following procedure.
1. A length of 0.5 m in a relaxed state (hereinafter also referred to as “relaxed length”) of the polyurethane elastic fiber was unwound from the wound body, and the yarn mass (g) was measured. The fineness of the polyurethane elastic fiber in the relaxed state (relaxed fineness A (dtex)) was calculated from the following formula. The measurement was performed 4 times and the average value was taken. The term "relaxed state" refers to a state in which the yarn is left unloaded for two hours or longer without load after being unwound from the wound body.
Relax fineness A (dtex) = yarn mass (g) x 10000/0.5 (m)
2. The polyurethane elastic fiber was unwound by feeding 50 m from the polyurethane elastic fiber wound body while maintaining the elongation rate by the feeding roll, and the yarn mass (g) was measured. The fineness of the polyurethane elastic fiber in the stretched state (printed fineness B (dtex)) was calculated from the following formula.
Print fineness B (dtex) = Yarn mass (g) x 10000/50 (m)
3. The following formula:
Elongation rate (%) = (A/B-1) x 100
Elongation rate (%) of the polyurethane elastic fiber in the wound body was calculated from the above.

(11) Speed responsiveness of elastic fiber Tensile tester (EZ-SX AUTOGRAPH manufactured by Shimadzu Corporation) was used to stretch the elastic fiber in an atmosphere of 20°C and 65% RH so that the initial length was 5 cm and the initial load was 0 cN without deflection. It is set in a testing machine, stretched to 100% elongation at elongation speeds of 200%/min and 2000%/min, and the stress (cN) at 50% elongation is measured. Here, the maximum stress at the elongation rate of 200% / min is R, the maximum stress at the elongation rate of 2000% / min is R ', and the following calculation formula:
Speed response ratio = R'/R
, the velocity response ratio of the elastic fiber was calculated. Separate samples are used for tensile tests at elongation rates of 200%/min and 2000%/min.

[Example 1]
2400 g of polytetramethylene ether diol having a number average molecular weight of 1800 and 775.78 g of 4,4′-diphenylmethane diisocyanate were reacted under a dry nitrogen atmosphere at 60° C. for 3 hours under stirring to obtain a terminal isocyanate capped A polyurethane prepolymer was obtained. 162.01 g of 1,4-butanediol was added to this polyurethane prepolymer and stirred for 15 minutes to obtain a thermoplastic polyurethane having a viscosity of 2000 poise (30° C.).
Thereafter, the thermoplastic polyurethane was put out on a Teflon (registered trademark) tray, and the thermoplastic polyurethane was annealed in a hot air oven at 110° C. for 19 hours while it was in the tray to obtain a thermoplastic polyurethane resin. This thermoplastic polyurethane resin had a weight average molecular weight of 200,000 in GPC.

Spinning was performed using the apparatus shown in FIG. The thermoplastic polyurethane resin described above was pulverized into powder of about 3 mm using a pulverizer UG-280 manufactured by Horai Co., Ltd. After drying the pulverized chips with a dehumidifying dryer at a temperature of 110° C. to a moisture content of 100 ppm, thermoplastic polyurethane resin powder was charged from the hopper 1 and melted in the extruder 2 . It was weighed and pressurized by a gear pump 3 installed in a spinning head 4, filtered through a filter, and discharged at a rate of 43.4 g/min from a spinneret with a diameter of 0.23 mm and 60 holes. After that, no cold air is applied to the area 50 cm from the nozzle outlet, 20 ° C cold air is blown from the cold air chamber at 0.5 m / sec in the section from 50 cm to 100 cm from the nozzle outlet, and 10 ° C cold air is applied to the yarn after 100 cm from the nozzle outlet. was blown from the cold air chamber 5 at 1.0 m/sec to melt-spun the fibers. At that time, each filament was bundled using a ring-type false twister 6 . The winding conditions were 650 m/min for the first godded roll 7, 670 m/min for the second godded roll 9, and 700 m/min for the winding roll 10. During winding, a processing agent containing polydimethylsiloxane as a main component and containing diethylene glycol dibenzoate is applied in the processing agent application unit 8, and the thermoplastic polyurethane elastic fiber of 620 dtex/60 filaments is wound onto a paper tube. to obtain a winding body.

The resulting thermoplastic polyurethane elastic fiber had a speed response ratio of 2.0. The thermoplastic polyurethane elastic fiber is 620 dtex and 60 filaments, and polyurethane synthesized from polytetramethylene ether glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO). The distance between the hard domains was 13 nm, the full width at half maximum of the peak of the azimuthal distribution was 80°, the molecular weight of the hard segment was 1005, and no crosslinked structure was included. The results are also shown in Table 1 below.

[Examples 2 to 5]
In the winding step of spinning, the same method as in Example 1 was performed, except that the speed ratio between the godded roller and the winding roller was changed to control the stretched state of the thermoplastic polyurethane elastic fiber in the wound body. A thermoplastic polyurethane elastic fiber was made.

[Examples 6 to 13]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the amount and type of the ester added to the treatment agent applied during spinning were changed.

[Example 14]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the ester added to the treating agent applied during spinning was eliminated and instead added to the polymer in the form of a masterbatch.

[Examples 15 to 20]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the proportion of silicone oil in the treatment agent applied during spinning was changed.

[Examples 21 to 26]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the coating amount of the treatment agent applied during spinning was changed.

[Example 27]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the polymerization was controlled so that the total number of moles of the chain extender consisting of the polymer polyol and the active hydrogen compound was greater than or equal to the number of moles of isocyanate. bottom.

[Examples 28-35]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the ratio of raw materials PTMG, MDI, and BDO was changed, and the molecular weight of the hard segment was changed. The molecular weight of the hard segment was decreased by increasing the molar amount of PTMG relative to MDI, and conversely increased by decreasing the molar amount of PTMG relative to MDI.

[Example 36]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the raw material PTMG was changed to polypropylene glycol (PPG).

[Example 37]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the raw material MDI was changed to tolylene diisocyanate (TDI).

[Example 38]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the raw material BDO was changed to ethylene glycol (EG).

[Examples 39-49]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the polymer discharge speed, winding roll speed, etc. were adjusted, and the number of filaments, single filament fineness, and total fineness were changed. The single yarn fineness and the total fineness are increased by increasing the polymer discharge speed or the winding roll speed, and conversely, the single yarn fineness and the total fineness are increased by decreasing the polymer discharge speed or increasing the winding roll speed. Reduced fineness.

[Examples 50-56]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the size of the spinneret hole diameter, the polymer ejection speed, the godet roll speed, and the take-up roll speed were adjusted to adjust the full width at half maximum of the peak of the azimuth angle distribution. made. By increasing the spinneret hole diameter and lowering the polymer discharge linear velocity, the orientation of the yarn between the spinneret and the first godded roll is increased. The full width at half maximum of the peak of the azimuthal distribution was reduced by increasing the total spinning speed and increasing the orientation into the yarn. Conversely, the full width at half maximum of the peak of the azimuth angle distribution was increased by decreasing the spinneret hole diameter, decreasing the speed of the two godded rolls, and decreasing the overall spinning speed.

[Examples 57 to 64]
In the same manner as in Example 1, except that the distance between the hard domains of the thermoplastic polyurethane elastic fiber was adjusted by changing the cooling conditions such as the distance directly under the die where the cold air was not applied, the temperature of the cold air in the cold air chamber, and the speed of the cold air. A thermoplastic polyurethane elastic fiber was made. The distance between the hard domains was shortened by applying cool air immediately below the die, lowering the temperature of the cold air, and increasing the velocity of the cold air, thereby performing rapid cooling. Conversely, the distance between hard domains was lengthened by cooling slowly.

[Comparative Examples 1 and 2]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the size of the spinneret hole diameter, the polymer ejection speed, the godet roll speed, and the take-up roll speed were adjusted to adjust the full width at half maximum of the peak of the azimuth angle distribution. made.

[Comparative Examples 3 and 4]
A thermoplastic polyurethane elastic fiber was produced in the same manner as in Example 1, except that the distance between the hard domains was adjusted by removing the gradient of the cold air and quenching in the spinning process.

[Comparative Example 5]
A commercially available dry-spun polyurethane elastic fiber ("Roica" manufactured by Asahi Kasei Corporation) was measured.

Tables 1 to 7 below show the production conditions and the measurement results of the obtained polyurethane elastic fibers in the above examples and comparative examples.

The thermoplastic polyurethane elastic fiber according to the present invention is used as a member of sanitary materials such as sanitary products and absorbent articles represented by disposable diapers, thereby exhibiting appropriate speed responsiveness and enabling the wearer to move. It is possible to obtain a product that does not easily shift and leave marks.

1 Hopper 2 Extruder 3 Gear Pump 4 Spinning Head 5 Cold Air Chamber 6 False Twisting Machine 7 1 Godded Roll 8 Treatment Agent Application Section 9 2 Godded Roll 10 Winding Roll

Claims (12)

A thermoplastic polyurethane characterized by having a distance between hard domains of 10 nm or more and 30 nm or less and a peak full width at half maximum of an azimuthal distribution of 50° or more and 130° or less, as measured by a small-angle X-ray scattering apparatus. elastic fiber. 2. The thermoplastic polyurethane elastic fiber according to claim 1, wherein the number of filaments is 10 or more and 160 or less. 3. The thermoplastic polyurethane elastic fiber according to claim 1 or 2, having a single filament fineness of 5 dtex or more and 30 dtex or less. The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, having a total fineness of 160 dtex or more and 1500 dtex or less. The thermoplastic polyurethane elastic fiber of any one of claims 1-4, comprising a polyurethane synthesized from a polymer polyol, 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol. The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 5, wherein the hard segment has a molecular weight of 750 or more and 1500 or less. The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 6, which is substantially free of crosslinks containing allophanate linkages. The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 7, which contains a treating agent in a content of 0.05% by mass or more and 5% by mass or less based on the mass of the thermoplastic polyurethane elastic fiber. 9. The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 8, wherein the thermoplastic polyurethane elastic fiber contains a treating agent, and the treating agent contains 10% by mass or more and 90% by mass or less of silicone oil relative to the mass of the treating agent. 2. The thermoplastic polyurethane elastic fiber according to item 1. 10 ppm or more and 1000 ppm or less of an ester or phosphate obtained by condensing a compound A and a compound B with respect to the mass of the thermoplastic polyurethane elastic fiber, and the compound A is a monocarboxylic acid having 4 or more and 30 or less carbon atoms. , a dicarboxylic acid having 4 to 30 carbon atoms, a tricarboxylic acid having 4 to 30 carbon atoms, and phosphoric acid, and the compound B is a monomonomer having 1 to 30 carbon atoms The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 9, which is any one selected from the group consisting of ols, diols with a molecular weight of 3000 or less, and triols with a molecular weight of 3000 or less. A wound body in which the thermoplastic polyurethane elastic fiber according to any one of claims 1 to 10 is wound around a pipe, wherein the elongation rate of the thermoplastic polyurethane elastic fiber in the wound body is 0.1. A wound body that is 1% or more and 10% or less. A sanitary material using the thermoplastic polyurethane elastic fiber according to any one of claims 1 to 10.

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