WO2023204157A1

WO2023204157A1 - Thermoplastic polyurethane elastic fiber

Info

Publication number: WO2023204157A1
Application number: PCT/JP2023/015215
Authority: WO
Inventors: 宗大内; 英之後藤
Original assignee: 旭化成株式会社
Priority date: 2022-04-22
Filing date: 2023-04-14
Publication date: 2023-10-26
Also published as: TW202346668A

Abstract

The present invention addresses the problem of providing a thermoplastic polyurethane elastic fiber having excellent NOx gas-induced yellowing resistance and heat resistance. The present invention relates to a thermoplastic polyurethane elastic fiber characterized by comprising 0.05 wt% to 5.00 wt% of at least one metal compound selected from the group consisting of a metal hydroxide, a metal carbonate, and a metal oxide, wherein the metal compound includes an alkali metal or an alkaline earth metal.

Description

thermoplastic polyurethane elastic fiber

The present invention relates to thermoplastic polyurethane elastic fibers.

Polyurethane elastic fibers are generally used in clothing and sanitary materials. Polyurethane elastic fibers used in clothing and sanitary materials are required to have yellowing resistance and heat resistance.
Patent Document 1 below discloses that a polyurethane elastic fiber obtained by dry spinning containing a hindered amine compound can improve the resistance to NOx gas yellowing.
Patent Document 2 below discloses that the NOx gas yellowing resistance of polyurethane resin can be improved by using a phenolic antioxidant, a hindered amine light stabilizer, a polyester compound, and a benzotriazole light stabilizer in combination. There is.
Patent Document 3 below describes a prepolymer with isocyanate groups at both ends obtained by reacting a polyol and a diisocyanate, and a prepolymer with hydroxyl groups at both ends obtained by reacting a polyol, a diisocyanate, and a low molecular weight diol. It is disclosed that the heat resistance of polyurethane elastic fibers can be improved by melt spinning a thermoplastic polyurethane resin.
Patent Document 4 below discloses that the heat resistance of polyurethane elastic fibers can be improved by using an oil agent made of polydimethylsiloxane in combination with a phenolic antioxidant.

JP2006-342448A Japanese Patent Application Publication No. 2009-19062 Japanese Patent Application Publication No. 2006-307409 Japanese Patent Application Publication No. 2003-20521

However, Cited Documents 1 to 4 do not disclose thermoplastic polyurethane elastic fibers that are resistant to NOx gas yellowing and heat resistant.

In view of the problems of the prior art described above, the problem to be solved by the present invention is to provide a thermoplastic polyurethane elastic fiber having excellent resistance to NOx gas yellowing and heat resistance.

In order to solve the above problems, the inventors of the present application have conducted extensive studies and repeated experiments, and as a result, they have found that 0.05wt of at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides. % or more and 5.00 wt% or less, and the metal compound contains an alkali metal or an alkaline earth metal.It was unexpectedly discovered that the above problem can be solved by a thermoplastic polyurethane elastic fiber, and the present invention This is what we have come to complete.

That is, the present invention is as follows.
[1] Contains at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides in an amount of 0.05 wt% or more and 5.00 wt% or less, and the metal compound is an alkali metal or A thermoplastic polyurethane elastic fiber characterized by containing an alkaline earth metal.
[2] The thermoplastic polyurethane elastic fiber according to [1] above, wherein the metal compound contains an alkaline earth metal.
[3] The thermoplastic polyurethane elastic fiber according to [2] above, wherein the alkaline earth metal is magnesium.
[4] The thermoplastic polyurethane elastic fiber according to any one of [1] to [3] above, wherein the metal compound is magnesium hydroxide.
[5] The polyurethane constituting the thermoplastic polyurethane elastic fiber is a polyurethane polymerized from a chain extender consisting of a polymer polyol, a diisocyanate, and an active hydrogen compound, according to any one of [1] to [4] above. thermoplastic polyurethane elastic fiber.
[6] The thermoplastic polyurethane elastic fiber according to [5] above, wherein the chain extender is a diol having a molecular weight of 60 or more and 120 or less.
[7] The thermoplastic polyurethane elastic fiber according to [5] or [6], wherein the diisocyanate is 4,4'-diphenylmethane diisocyanate (MDI).
[8] The thermoplastic polyurethane elastic fiber according to any one of [5] to [7], wherein the ratio of the hard segment (Mh fraction) consisting of the chain extender and the diisocyanate is 20% or more and 40% or less. .
[9] Any one of [5] to [8] above, wherein the total number of moles of the chain extender and the polymer polyol is 1.001 times or more and 1.100 times or less relative to the number of moles of the diisocyanate. The thermoplastic polyurethane elastic fibers described.
[10] The thermoplastic polyurethane elastic fiber according to any one of [1] to [9] above, which has a total fineness of 160 dtex or more and 2000 dtex or less.
[11] The thermoplastic polyurethane elastic fiber according to any one of [1] to [10] above, which is a multifilament.
[12] The thermoplastic polyurethane elastic fiber according to any one of [1] to [11] above, which has a coefficient of variation in fineness unevenness in the yarn length direction of 3.0% or more and 10.0% or less.
[13] The thermoplastic polyurethane elastic fiber according to any one of [1] to [12], wherein the difference between the maximum fineness and the minimum fineness in the yarn length direction is 10 dtex or more and 150 dtex or less.
[14] The thermoplastic polyurethane elastic fiber according to any one of [1] to [13], wherein the thermoplastic polyurethane elastic fiber has an outflow start temperature of 150° C. or more and 220° C. or less as measured by a flow tester.

The thermoplastic polyurethane elastic fiber that is one embodiment of the present invention is a thermoplastic polyurethane elastic fiber that has the above structure and has excellent NOx gas yellowing resistance and heat resistance.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail. The present invention is not limited to the following embodiment, but can be modified and implemented within the scope of the gist.

[Metal compound]
The thermoplastic polyurethane elastic fiber of the present embodiment contains at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides at 0.05 wt% or more and 5.00 wt% or less, preferably 0. It is characterized by containing .10 wt% or more and 1.00 wt% or less, more preferably 0.30 wt% or more and 0.50 wt% or less. By containing at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides in an amount of 0.05 wt% or more and 5.00 wt% or less, NOx gas yellowing resistance and heat resistance are improved. It will be excellent. By containing at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides in an amount of 0.05 wt% or more and 5.00 wt% or less, NOx gas yellowing resistance and heat resistance are improved. Although the reason for the improvement is not yet clear, the inventors estimate as follows. By containing at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides in an amount of 0.05 wt% or more, effective NOx gas yellowing resistance is exhibited, and , 5.00 wt% or less, the polymer ratio in the polyurethane elastic fibers does not drop too much and heat resistance can be maintained.

In the metal compound, the metal element preferably contains an alkali metal or an alkaline earth metal. Moreover, it is more preferable that an alkaline earth metal is included. Further, the alkaline earth metal is preferably calcium or magnesium, and more preferably magnesium. If the metal element is an alkali metal or an alkaline earth metal, the effect of improving NOx gas yellowing resistance will be even higher. The reason why the NOx gas yellowing resistance can be improved by using an alkaline earth metal as the metal element of the metal compound is not yet clear, but the inventors speculate as follows. Since alkaline earth metals have a large electric charge, they easily adsorb NOx gas and suppress the attack of NOx gas on thermoplastic polyurethane elastic fibers, which is estimated to improve the NOx gas yellowing resistance of thermoplastic polyurethane elastic fibers. ing.

It is particularly preferable that the metal compound is magnesium hydroxide because the effect of improving the NOx gas yellowing resistance is further increased. The reason why the NOx gas yellowing resistance can be improved by using magnesium hydroxide as the metal compound is not yet clear, but the inventors speculate as follows. Magnesium hydroxide is a solid base with high base strength and easily reacts with acidic NOx gas, so it is estimated that the NOx gas yellowing resistance is improved.

[Thermoplastic polyurethane]
In the present embodiment, the thermoplastic polyurethane constituting the thermoplastic polyurethane elastic fiber may have a structure polymerized from diisocyanates, polymer polyols, diols, diamines, etc., and has thermoplasticity, in particular. It is not limited. Moreover, the polymerization method is not particularly limited either. The thermoplastic polyurethane may be, for example, a polyurethane polymerized from a low molecular weight diamine as a chain extender consisting of a diisocyanate, a polymer polyol, and an active hydrogen compound; It may also be a polyurethane (hereinafter also referred to as "polyurethane urethane") polymerized from a low molecular weight diol as a chain extender consisting of. Trifunctional 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, "thermoplastic" means that it can be melted by heating below the decomposition temperature, exhibits plastic flow while in a molten state, and has the reversible property of solidifying upon cooling. means. Generally, polyurethane resins begin to decompose at temperatures above 230°C.

[Polymer polyol]
Examples of the polymer polyol include, but are not limited to, polymer diols such as polyether diols, polyester diols, and polycarbonate diols. From the viewpoint of hydrolysis resistance, the polymer polyol is preferably a polyether polyol.

Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, copolymer diols that are copolymers of tetrahydrofuran (THF) and neopentyl glycol, and copolymers of THF and 3-methyltetrahydrofuran. Certain copolymer diols are mentioned. These polyether polyols may be used alone or in combination of two or more. Further, from the viewpoint of easily obtaining elastic fibers with excellent elongation, stretch recovery properties, and heat resistance, the number average molecular weight of the polymer diol is preferably 1000 or more and 8000 or less. From the viewpoint of light embrittlement, the polyether polyol is preferably polytetramethylene ether glycol, a copolymerized diol that is a copolymer of THF and neopentyl glycol, and a polyol that is a blend of these.

[Diisocyanate]
Examples of diisocyanates include aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates. Examples of aromatic diisocyanates include, but are not limited to, diphenylmethane diisocyanate (hereinafter also referred to as "MDI"), tolylene diisocyanate, 1,4-diisocyanate benzene, xylylene diisocyanate, 2,6-naphthalene diisocyanate, and the like. It will be done. 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, and cyclohexane. Examples include 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, and octahydro 1,5-naphthalene diisocyanate. These diisocyanates may be used alone or in combination of two or more. In particular, from the viewpoint of elastic fiber recovery properties, the diisocyanate is preferably an aromatic diisocyanate, and more preferably MDI. Further, by using MDI, a cyclic structure is introduced into the polymer skeleton, thereby increasing rigidity and improving heat resistance.

[Chain extender]
The chain extender made of an active hydrogen compound is preferably at least one selected from the group consisting of low molecular weight diamines and low molecular weight diols. Note that 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 the low molecular weight diamine as a chain extender made of an active hydrogen compound include 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 the low molecular weight diol as a chain extender consisting of an active hydrogen compound include ethylene glycol, 1,3-propanediol, 1,4-butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, 1-methyl-1 , 2-ethanediol, 1,6-hexanediol, 1,8-octanediol and the like. These low molecular weight diols may be used alone or in combination of two or more.

The chain extender is preferably a diol with a molecular weight of 60 or more and 120 or less, from the viewpoint of stretch recovery of elastic fibers and from the viewpoint of improving heat resistance and NOx gas yellowing resistance. The active hydrogen compound which is a diol with a molecular weight of 60 or more and 120 or less is preferably ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, More preferred are 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol, and most preferred is 1,4-butanediol.

[Method of synthesizing thermoplastic polyurethane]
Thermoplastic polyurethane can be obtained using a known polyurethanization reaction technique, and may be produced by either a one-shot method or a prepolymer method. In the case of the prepolymer method, the polymer polyol and diisocyanate are placed in a reaction tank equipped with a nitrogen purge, a hot water jacket, and a stirrer in a molar ratio of preferably 1.0:1.8 to 3.0, more preferably 1.0: By adding at a concentration of 2.0 to 2.5 and reacting, a prepolymer having isocyanate groups at both ends is obtained. Next, a chain extender is added to this prepolymer with isocyanate groups at both ends to perform a chain extension reaction. Thereafter, solid phase polymerization is performed to obtain polyurethane having a predetermined molecular weight. After uniformly mixing the prepolymer and the chain extender, the polymer may be obtained continuously or semi-continuously using a cylindrical pipe or a twin-screw extruder, followed by solid phase polymerization.

It is preferable that the total number of moles of the chain extender and the polymer polyol is 1.001 times or more and 1.100 times or less of the number of moles of the diisocyanate, since heat resistance and NOx gas yellowing resistance can be achieved at the same time. The reason why resistance to NOx gas yellowing and heat resistance can be improved by setting the total number of moles of the chain extender and polymer polyol to 1.001 times or more and 1.100 times or less relative to the number of moles of diisocyanate is still unclear. However, the inventors estimate as follows. If the total number of moles of the chain extender and polymer polyol is 1.001 times or more of the number of moles of diisocyanate, it is possible to reduce the amount of diisocyanate-derived structures in the molecule that easily adsorb NOx gas, thereby improving NOx resistance. Gas yellowing is improved. On the other hand, if the total number of moles of the chain extender and the polymer polyol is 1.100 times or less of the number of moles of the diisocyanate, ligand exchange between the hydroxyl group of the thermoplastic polyurethane and the metal salt becomes difficult to occur, and the metal salt Since it becomes easier to exhibit the NOx gas yellowing resistance effect, the NOx gas yellowing resistance is improved. Further, if the total number of moles of the chain extender and the polymer polyol is 1.001 times or more the number of moles of the diisocyanate, the molecular weight of the thermoplastic polyurethane tends to increase, thereby improving heat resistance.

[Method for producing thermoplastic polyurethane elastic fiber]
The spinning method is not particularly limited as long as the desired physical properties can be obtained; for example, in addition to the method of feeding thermoplastic polyurethane chips into an extruder, heating, and melt-spinning, After that, a method of mixing and spinning a polyisocyanate compound, adding a reaction product of a prepolymer with isocyanate groups at both ends and an active hydrogen compound to the prepolymer with isocyanate groups at both ends, and continuously producing it without going through chipping. An example is a spinning method.

The polyurethane charged into the extruder is 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, and then it is discharged from the spinneret, air-cooled in a cold air chamber, and treated with a treatment agent, and then passed through a godet roll. It is wound up.

In the spinning process, the temperature of the die, cold air speed, cold air temperature, focusing position, and spinning speed are adjusted to precisely control the fiber temperature profile and spinning tension. The temperature of the die is preferably 180°C to 220°C, more preferably 200°C to 210°C. A common melt spinning cooling method such as applying cold air perpendicularly to the running direction of the yarn from directly below the spinneret is used, and the wind speed of the cold air is preferably 0.2 m/s to 2.0 m/s, more preferably 0.5 m/s to 1.2 m/s, and the cold air temperature is preferably 5°C to 20°C, more preferably 7°C to 15°C. One way to focus multifilaments is to install a false twister between the spinneret and the godet roll, propagate the twist from the bottom depending on the strength of the twist, focus the filaments together, and control the height of the focus point. Can be mentioned. As the false twisting method, a general method can be selected, such as air false twisting using an air nozzle or a ring false twisting machine that brings the material into contact with a rotating ring.

In the thermoplastic polyurethane elastic fiber of this embodiment, the method of containing at least one metal compound consisting of a metal hydroxide, a metal carbonate, and a metal oxide in an amount of 0.05 wt% or more and 5.00 wt% or less is particularly limited. However, for example, there is a method in which it is added during the preparation of raw materials before the prepolymer reaction between a polymer polyol and diisocyanate, a method in which it is added in the middle of the chain extension reaction process between a prepolymer and an active hydrogen compound, and a masterbatch containing a metal compound. For example, a method of adding 100% during spinning can be mentioned.

The thermoplastic polyurethane elastic fiber of this embodiment may contain polymers other than polyurethane and additives, such as antioxidants, light stabilizers, ultraviolet absorbers, gas discoloration prevention agents, as long as the desired effects of the present invention are not lost. It may contain agents, dyes, activators, matting agents, pigments, lubricants, etc.

The thermoplastic polyurethane elastic fiber of this embodiment may contain a processing agent such as an oil agent from the viewpoint of unwinding property, processability, etc. Examples of the processing agent include, but are not limited to, silicone oils such as dimethyl silicone, mineral oils, and combinations thereof. The method of applying the treatment agent is not particularly limited, and examples thereof include a method of applying the treatment agent using an oiling roller or the like.

In the thermoplastic polyurethane elastic fiber of the present embodiment, the ratio of hard segments consisting of a chain extender and diisocyanate (hereinafter referred to as Mh fraction) is preferably 20% or more and 40% or less, more preferably 20% or more and 35%. Below, it is more preferably 22% or more and 30% or less. When the Mh fraction is 20% or more and 40% or less, both heat resistance and NOx gas yellowing resistance can be improved. The reason why the NOx gas yellowing resistance and heat resistance can be improved by setting the Mh fraction to 20% or more and 40% or less is not yet clear, but the inventors speculate as follows. When the Mh fraction is 20% or more, hydrogen bonds between urethane bonds increase, heat resistance improves, and the presence of metal salts around the hard segment increases, improving NOx gas yellowing resistance. do. On the other hand, when the Mh fraction is 40% or less, when the diisocyanate contains aromatic rings, the amount of aromatic rings that yellow due to adsorption of NOx gas decreases, thereby improving resistance to NOx gas yellowing. Note that a detailed method for calculating the Mh fraction will be described later.

The total fineness of the polyurethane elastic fiber of this embodiment is preferably 160 dtex or more and 2000 dtex or less, more preferably 300 dtex or more and 1500 dtex or less, and even more preferably 600 dtex or more and 1000 dtex or less.

The polyurethane elastic fiber of this embodiment may be either a monofilament or a multifilament, but is preferably a multifilament. When the polyurethane elastic fiber is a multifilament, the number of single yarns is preferably 14 or more and 140 or less.

The coefficient of variation in fineness unevenness in the yarn length direction of the thermoplastic polyurethane elastic fiber of the present embodiment is preferably 3.0% or more and 10.0% or less, more preferably 3.0% or more and 9.5% or less, and even more preferably It is 3.5% or more and 9.0% or less. If the variation coefficient of fineness unevenness is 3% or more and 10% or less, both NOx gas yellowing resistance and heat resistance can be improved. Although it is not yet clear why the NOx gas yellowing resistance and heat resistance are improved by having a fineness unevenness variation coefficient of 3.0% or more and 10.0% or less, the inventors estimate as follows. There is. If the variation coefficient of fineness unevenness is 3.0% or more, light is likely to be diffusely reflected on the fiber surface, making the fiber appear opaque, making it difficult to visually recognize yellowing inside the fiber, and making the yellowing appear faint. If the unevenness variation coefficient of fineness is 10.0% or less, yarn breakage due to heat reception at fine fineness points can be suppressed, and heat resistance is improved. The method of controlling the variation coefficient of fineness unevenness is not particularly limited as long as the desired physical properties can be obtained; for example, a method of enlarging the diameter of the spinneret used for melt spinning to generate draw resonance, Examples include a method of increasing the amount of yarn to cause shark skin or melt fracture, and a method of changing the cooling intensity during the spinning process to cause yarn shaking.

The difference between the maximum fineness and the minimum fineness in the yarn length direction of the thermoplastic polyurethane elastic fiber of this embodiment is preferably 10 dtex or more and 150 dtex or less, more preferably 15 dtex or more and 100 dtex or less, and even more preferably 20 dtex or 80 dtex or less. If the difference between the maximum fineness and the minimum fineness is 10 dtex or more and 150 dtex or less, both NOx gas yellowing resistance and heat resistance can be improved. The reason why the NOx gas yellowing resistance and heat resistance are improved due to the difference between the maximum fineness and the minimum fineness of 10 dtex or more and 150 dtex or less is not yet clear, but the inventors speculate as follows. If the difference between the maximum fineness and the minimum fineness is 10 dtex or more, light is likely to be diffusely reflected on the fiber surface, making the fiber appear opaque, making it difficult to visually recognize the yellowing inside the fiber, making the yellowing appear faint. If the difference between the maximum fineness and the minimum fineness is 150 dtex or less, yarn breakage due to heat reception at fine fineness points can be suppressed, and heat resistance is improved. The method of controlling the difference in fineness is not particularly limited as long as the desired physical properties can be obtained. For example, there may be a method of enlarging the diameter of the spinneret used for melt spinning to generate draw resonance, or a method of increasing the discharge amount. Examples include a method of increasing the number of yarns, causing shark skin or melt fracture, and a method of changing the cooling intensity during the spinning process to cause yarn shaking.

From the viewpoint of improving heat resistance and NOx gas yellowing resistance, the thermoplastic polyurethane elastic fiber of this embodiment preferably has an outflow start temperature measured by a flow tester of 150°C or more and 220°C or less, more preferably 150°C or more. The temperature is below 200°C. The reason why heat resistance and NOx gas yellowing resistance can be improved by setting the outflow start temperature to 150° C. or more and 220° C. or less is not yet clear, but the inventors estimate as follows. By setting the outflow start temperature to 150°C or higher, the structural change of the thermoplastic polyurethane due to heat reception is reduced, so heat resistance can be improved.On the other hand, by setting the outflow start temperature to 220°C or lower, the viscosity at the time of melting is reduced. By improving wettability, metal salts are uniformly dispersed, and NOx gas yellowing resistance is improved.

The present invention will be specifically explained using the following Examples and Comparative Examples, but the scope of the present invention is not limited by the Examples.
First, methods for evaluating physical properties and the like used in Examples and Comparative Examples will be explained.

<Quantification of constituent components of thermoplastic polyurethane>
The structure of the chain extender consisting of an active hydrogen compound and the diisocyanate constituting the thermoplastic polyurethane contained in the thermoplastic polyurethane elastic fiber was specified using NMR. Specifically, NMR was measured under the following conditions to identify the structures of the diisocyanate and chain extender. The structures of the diisocyanate and chain extender can be determined from the peak positions determined by NMR measurement.
Measuring device: Bruker Biospin Avance600
Measurement nucleus: ^1H
Resonance frequency: 600MHz
Number of accumulations: 256 times Measurement temperature: Room temperature Solvent: Deuterated dimethylformamide Measurement concentration: 1.5% by weight
Chemical shift standard: dimethylformamide (8.0233ppm)

<How to calculate the ratio of the total number of moles of chain extender and polymer polyol to the number of moles of diisocyanate (hereinafter expressed as OH/NCO)>
The OH/NCO of thermoplastic polyurethane elastic fiber is determined by the following formula (1) based on the integral value of the corresponding peak by NMR measurement:
OH/NCO={(Hh+Hs)/4}/(Hi/x)...Formula (1)
Calculated by.
During the ceremony,
Hh: Integral value derived from the methylene group of the active hydrogen compound adjacent to the urethane bond Hs: Integral value derived from the methylene group of the polymer polyol adjacent to the urethane bond Hi: Integral value derived from the hydrogen compound in the diisocyanate x: Total hydrogen of the diisocyanate is the number of

<Method for quantifying the ratio of hard segments (Mh fraction)>
The Mh fraction of the thermoplastic polyurethane elastic fiber is expressed by the following formulas (2) to (5):
Ms={Mdo+Mdi(N1-N0)}/(N1-N0-1)-2Mdi...Formula (2)
Mh={Mda(N1-1)+Mdi×N0}/(N1-N0-1)+2Mdi...Formula (3)
N0=0.03806N1 ⁴ -0.3997N1 ³ +1.617N1 ² -2.144N1 ¹ +0.8795...Formula (4)
Mh fraction (%) = {Mh/(Ms+Mh)}×100...Equation (5)
It is calculated by solving simultaneous equations.
During the ceremony,
Ms: number average molecular weight of soft segment portion Mdo: number average molecular weight of polymer polyol Mdi: molecular weight of isocyanate N1: molar ratio of isocyanate to polymer polyol N0: molar ratio of unreacted isocyanate to polymer polyol Mh: number of hard segment portions Average molecular weight Mda: Molecular weight of chain extender (number average molecular weight when using a mixture of two or more types)
Mdi: Molecular weight of isocyanate.

<Identification and quantitative method of metal compounds>
Thermoplastic polyurethane elastic fibers are wrapped around a glass plate and analyzed by XRD (Rigaku Ultima-IV), and the chemical composition of the metal compound contained can be identified by comparing the analyzed spectrum with data on the database. Once the identification of the metal compound by XRD is completed, a sample is prepared by wrapping thermoplastic polyurethane elastic fibers tightly around a PP film with holes in the center, and analyzed by XRF (Rigaku ZSX-100e) to determine the composition of the metal compound. The content of the metal compound can be determined from the detection intensity of the element. When quantifying, a calibration curve using the same metal compound as the contained metal compound may be used, if necessary.

<Measurement of outflow start temperature of thermoplastic polyurethane elastic fibers>
The outflow start temperature of the thermoplastic polyurethane elastic fiber is measured using a flow tester model CFT-500D (manufactured by Shimadzu Corporation). The thermoplastic polyurethane elastic fibers are not pre-treated to remove processing agents such as oil agents, and 1.5 g of the thermoplastic polyurethane elastic fibers are sampled per measurement to measure the outflow start temperature. A die (nozzle) with a diameter of 0.5 mm and a thickness of 1.0 mm was used, an extrusion load of 49 N was applied, and after a preheating time of 240 seconds at an initial setting temperature of 120 °C, the temperature was increased to 250 °C at a rate of 3 °C/min. Find a curve of stroke length (mm) and temperature when the temperature increases rapidly. As the temperature increases, the polymer within the toner heats up and begins to flow out of the die. The temperature at this time is defined as the outflow start temperature.

<Measurement method of fineness unevenness variation coefficient>
The measurement of the variation coefficient of fineness unevenness is carried out by adjusting the rotational speed of two godet rolls so that the thermoplastic polyurethane elastic fiber is stretched twice, and by setting the following device between the godet rolls. The outer diameter of the elastic fiber was measured from two directions perpendicular to each other using a laser, and the ratio of the average deviation of the diagonal length calculated from the Pythagorean theorem to the average value was defined as the coefficient of variation in fineness unevenness. The measurement data used was the average value of 50,000 points of data measured at 160 points/second.
Measuring device: LS9006D (manufactured by Keyence Corporation)
Measurement type: Outer diameter Minimum display unit: 0.0001mm
Number of measurement points: 50000
Accumulation cycle: ×100

<How to measure fineness>
To measure fineness, thermoplastic polyurethane elastic fibers are cut vertically, the yarn cross section is observed using the following equipment and conditions, and the total cross-sectional area of the yarn is calculated by automatic area measurement, and the fineness per unit length is calculated. The following formula (6):
d=D×1.1(g/cm ³ )×10 ⁶ ...Formula (6)
{where d is the fineness (dtex) and D is the total cross-sectional area (cm ² ) of the yarn. }
Calculated using.
Measuring device: VHX-7000 (manufactured by Keyence Corporation)
Lens used: VH-Z100R
Magnification: 500x Measurement: Automatic area measurement Extraction method: Brightness <Method for measuring the difference between the maximum and minimum fineness of polyurethane elastic fibers>
To measure the difference between the maximum fineness and the minimum fineness, the thermoplastic polyurethane elastic fiber is cut vertically, the yarn cross section is observed using the following equipment and conditions, and the total cross-sectional area of the yarn is calculated by automatic area measurement. The fineness per unit length was calculated from the difference between the maximum fineness and the minimum fineness when the fineness per unit length was calculated at 10 points using the above formula (6) at intervals of 5 mm in the yarn length direction.
Measuring device: VHX-7000 (manufactured by Keyence Corporation)
Lens used: VH-Z100R
Magnification: 500x Measurement: Automatic area measurement Extraction method: Brightness

<Heat resistance evaluation method>
The thermoplastic polyurethane elastic fiber was held in a state of being stretched to twice its original size, and when it was pressed against a heat source of 110° C., the time until the fiber broke (the number of seconds for thermal cutting) was evaluated as an index of heat resistance.

<Evaluation method for NOx gas yellowing resistance>
1. ΔYI value Using thermoplastic polyurethane elastic fibers, yellowing was evaluated according to JIS-L-0855 color fastness test method to nitrogen oxide gas and weak test method. Judgment is made by comparing the yellowness YI value using a Macbeth colorimeter (manufactured by Macbeth) with the untreated sample YI0 using the following formula (7):
ΔYI=YI−YI0…Formula (7)
Evaluation was made using the ΔYI value obtained by.
The smaller the ΔYI value, the less yellowing occurs, and the larger the ΔYI value, the more likely it is to yellow.

2. Yellowing Visibility The thermoplastic polyurethane elastic fibers yellowed by the method 1 above were compared with the color code and evaluated on a 10-point scale. Specifically, a total of 18 people, 10 in their 20s and 2 in their 30s to 60s, were asked to select the color code closest to the color of yellowed thermoplastic polyurethane elastic fibers, and the average The points were taken as the evaluation score for yellowing visibility. The color codes and evaluation scores used are as follows, and the higher the evaluation score, the less likely it is to yellow.
#FFD500: 1 point #FFD91A: 2 points #FFDD33: 3 points #FFE14D: 4 points #FFE666: 5 points #FFEA80: 6 points #FFEE99: 7 points #FFF2B3: 8 points #FFF7CC: 9 points #FFFBE6: 10 points

Both the ΔYI value and yellowing visibility evaluation are evaluations of NOx gas yellowing resistance. The ΔYI value is not affected by human visibility, and conversely, the yellowing visibility is affected by the human visibility, so by comparing the yellowing visibility of samples with the same ΔYI value, it is possible to determine the human visibility. The NOx gas yellowing resistance can be evaluated based on the following.

[Example 1]
<Synthesis of thermoplastic polyurethane resin>
2400 g of polytetramethylene ether diol having a number average molecular weight of 1800 and 750.78 g of 4,4'-diphenylmethane diisocyanate were reacted with stirring at 60° C. for 3 hours in a dry nitrogen atmosphere to obtain a terminal capped product with isocyanate. A polyurethane prepolymer was obtained. 151.20 g of 1,4-butanediol was added to this polyurethane prepolymer and stirred for 15 minutes to obtain a polyurethane with a viscosity of 2000 poise (30° C.).
Thereafter, it was dispensed onto a Teflon (registered trademark) tray, and the polyurethane was annealed in a hot air oven at 110° C. for 16 hours while remaining in the tray to obtain a thermoplastic polyurethane resin.

<Preparation of masterbatch>
The thermoplastic polyurethane resin thus obtained was pulverized into a powder of approximately 3 mm using a UG-280 pulverizer manufactured by Horai. After drying the crushed chips in a dehumidifying dryer at a temperature of 110°C to a moisture content of 100 ppm, polyurethane resin powder and magnesium hydroxide were put into a hopper at a predetermined ratio, melted into strands in an extruder, and heated at a temperature of 20°C. The mixture was cooled in a water bath at 10°C and pelletized using a plastic processing machine SCF-100 manufactured by Isuzu Kakoki to obtain a masterbatch of magnesium hydroxide containing 10 wt% of the active ingredient.

<Preparation of thermoplastic polyurethane elastic fiber>
Magnesium hydroxide-containing polyurethane resin powder, which is a mixture of thermoplastic polyurethane resin powder and magnesium hydroxide masterbatch at a weight ratio of 95:5, is weighed and pressurized using a gear pump installed in the head, filtered through a filter, and then passed through a die. The liquid was discharged at a temperature of 210° C. from a nozzle with a diameter of 0.23 mm and 60 holes at a discharge rate of 620 dtex. Thereafter, melt spinning was performed by blowing cold air from a cold air chamber whose temperature was adjusted to 15 to 17°C and the speed of the cold air to 0.8 to 1.0 m/s, and applying it perpendicularly to the fibers. Thereafter, the multifilament is twisted using a ring-type false twisting machine, and wound into a paper tube while applying a treatment agent mainly composed of polydimethylsiloxane and mineral oil to a 620 dtex/60 A spool of filament thermoplastic polyurethane elastic fiber was obtained. Magnesium hydroxide contained in this thermoplastic polyurethane elastic fiber is 0.50wt%, Mh fraction is 24%, fineness variation coefficient is 4.0%, OH/NCO is 1.010, and thermal cutting time is 600%. The thermoplastic polyurethane elastic fiber had a ΔYI value of 8, a difference between the maximum fineness and the minimum fineness of 30 dtex, an outflow start temperature of 160° C., and a yellowing visibility evaluation of 10 points. The results are also shown in Table 1 below.

[Examples 2 to 6]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1, except that the ratio of the polyurethane resin and masterbatch was adjusted to increase or decrease the amount of magnesium hydroxide contained in the polyurethane elastic fibers. The results are shown in Table 1 below.

[Examples 7 to 12]
The metal compounds were magnesium carbonate (Example 7), magnesium oxide (Example 8), calcium hydroxide (Example 9), calcium carbonate (Example 10), sodium carbonate (Example 11), and potassium carbonate (Example 12). ) A thermoplastic polyurethane elastic fiber was obtained in the same manner as in Example 1 except that The results are shown in Table 1 below.

[Examples 13 to 17]
Chain extenders consisting of active hydrogen compounds were used as ethylene glycol (Example 13), 1,3-propanediol (Example 14), 1,6-hexanediol (Example 15), and 1,8-octanediol (Example 15). 16), thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1 except that 1,10-decanediol (Example 17) was used. The results are shown in Table 1 below.

[Example 18, 19]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1, except that methylene bis(cyclohexyl isocyanate) (H12MDI) (Example 18) and 1,6-hexamethylene diisocyanate (HDI) (Example 19) were used. . The results are shown in Table 1 below.

[Examples 20 to 26]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1, except that the Mh fraction of the thermoplastic polyurethane elastic fibers was increased or decreased by adjusting the molar ratio of polymer polyol and diisocyanate. The results are shown in Table 1 below.

[Examples 27 to 33]
A thermoplastic polyurethane elastic fiber was obtained in the same manner as in Example 1, except that the molar ratio of the polymer polyol, diisocyanate, and diol was adjusted to change the OH/NCO of the thermoplastic polyurethane elastic fiber. The results are shown in Table 2 below.

[Examples 34-41]
Thermoplastic polyurethane elastic fibers were produced in the same manner as in Example 1, except that the spinning temperature, spinneret diameter, discharge rate, cooling conditions, and winding conditions during spinning were adjusted to change the variation coefficient of fineness unevenness of the thermoplastic polyurethane elastic fibers. I got it. The results are shown in Table 2 below.

[Examples 42 to 49]
The same method as in Example 1 was used except that the spinning temperature, spinneret diameter, discharge rate, cooling conditions, and winding conditions during spinning were adjusted to change the fineness difference (maximum fineness - minimum fineness) of the thermoplastic polyurethane elastic fibers. A thermoplastic polyurethane elastic fiber was obtained. The results are shown in Table 2 below.

[Examples 50 to 54]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1, except that the molecular weight of the thermoplastic polyurethane was adjusted by adjusting the molecular weight of the polymer polyol, and the outflow start temperature of the thermoplastic polyurethane elastic fibers was changed. The results are shown in Table 3 below.

[Comparative example 1]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1 except that no metal compound was added. The results are shown in Table 3 below.

[Comparative example 2]
Thermoplastic polyurethane elastic fibers were obtained in the same manner as in Example 1, except that the amount of masterbatch added was adjusted and the amount of magnesium hydroxide contained in the polyurethane elastic fibers was changed to 10.0 wt%. The results are shown in Table 3 below.

[Comparative Examples 3 to 6]
In the same manner as in Example 1, except that the metal compounds were changed to magnesium stearate (Comparative Example 3), calcium stearate (Comparative Example 4), zinc oxide (Comparative Example 5), and aluminum hydroxide (Comparative Example 6). A thermoplastic polyurethane elastic fiber was obtained. The results are shown in Table 3 below.

The thermoplastic polyurethane elastic fiber according to the present invention can be suitably used for clothing such as innerwear, stockings, and compression wear, and sanitary materials such as gather members and diapers.

Claims

Contains at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates, and metal oxides in an amount of 0.05 wt% or more and 5.00 wt% or less, and the metal compound is an alkali metal or alkaline earth metal compound. A thermoplastic polyurethane elastic fiber characterized by containing metal.
The thermoplastic polyurethane elastic fiber according to claim 1, wherein the metal compound contains an alkaline earth metal.
The thermoplastic polyurethane elastic fiber according to claim 2, wherein the alkaline earth metal is magnesium.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, wherein the metal compound is magnesium hydroxide.
The thermoplastic polyurethane according to any one of claims 1 to 3, wherein the polyurethane constituting the thermoplastic polyurethane elastic fiber is a polyurethane polymerized from a chain extender consisting of a polymer polyol, a diisocyanate, and an active hydrogen compound. elastic fiber.
The thermoplastic polyurethane elastic fiber according to claim 5, wherein the chain extender is a diol with a molecular weight of 60 or more and 120 or less.
The thermoplastic polyurethane elastic fiber according to claim 5, wherein the diisocyanate is 4,4'-diphenylmethane diisocyanate (MDI).
The thermoplastic polyurethane elastic fiber according to claim 5, wherein the ratio of the hard segment (Mh fraction) consisting of the chain extender and the diisocyanate is 20% or more and 40% or less.
The thermoplastic polyurethane elastic fiber according to claim 5, wherein the total number of moles of the chain extender and the polymer polyol is from 1.001 times to 1.100 times the number of moles of the diisocyanate.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, wherein the total fineness of the thermoplastic polyurethane elastic fiber is 160 dtex or more and 2000 dtex or less.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, which is a multifilament.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, which has a coefficient of variation in fineness unevenness in the yarn length direction of 3.0% or more and 10.0% or less.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, wherein the difference between the maximum fineness and the minimum fineness in the yarn length direction is 10 dtex or more and 150 dtex or less.
The thermoplastic polyurethane elastic fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane elastic fiber has a flow start temperature of 150° C. or more and 220° C. or less as measured by a flow tester.