Polyurethane elastic yarn

Abstract

To provide a polyurethane elastic yarn which is good in a heat-setting property in a broad temperature range and high in a heat adhesive force in a broad temperature range while maintaining elastic characteristics (permanent set and elongation).SOLUTION: The polyurethane elastic yarn including a polyurethane polymer [A] and a polyurethane polymer [B], and a ratio of the polyurethane polymer [A] and the polyurethane polymer [B] is 1 to 30 pts.mass : 99 to 70 pts.mass or 70 to 99 pts.mass : 30 to 1 pts.mass; exothermic peaks (crystallization peak) of the polyurethane elastic yarn fall in a range of 110°C to 210°C measured by a differential scanning calorimeter (DSC); and a calorific value of the exothermic peaks is 3.0 J / g or more and 100 J / g or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polyurethane elastic fibers. More specifically, it relates to polyurethane elastic fibers that maintain stretch characteristics (permanent strain rate and elongation), have good heat setting properties in a wide temperature range, and have high heat adhesion in a wide temperature range.

Background Art

[0002] Elastic fibers are widely used in stretch clothing applications such as legwear, innerwear, and sportswear due to their excellent stretch characteristics, sanitary applications (medical material applications) such as paper diapers and sanitary napkins, and industrial material applications. Among such elastic fibers, particularly high heat setting properties are required for polyurethane elastic fibers. For example, when manufacturing a stretch fabric containing polyurethane elastic fibers, high heat setting properties are important for determining the fabric dimensions and for adjusting the shape and appearance of the ends of the fabric in the case of a piece of fabric. Furthermore, by using a polyurethane elastic fiber having high heat setting properties, the processing temperature can be lowered, and a fiber product with excellent texture can be obtained. Lowering the processing temperature also has the advantage of reducing energy consumption and reducing utility costs.

[0003] When such elastic fibers are used in the general clothing field, they are usually cross-woven, and then the fabric goes through manufacturing processes such as cutting, sewing, and finishing to become a product. When a fabric cross-woven using polyurethane elastic fibers is cut and sewn, the edges are likely to fray, and furthermore, the polyurethane elastic fibers come out of the fabric weave structure at the frayed edges, resulting in a problem that the stretch characteristics of the fabric in that part deteriorate.

[0004] Therefore, in normal products, some edge finishing is carried out to prevent the edges from fraying after cutting. For example, it is common to fold the cut edge back to double it and sew it, or to wrap it with a separate cloth such as tape and sew it. However, such post-treatment operations for preventing fraying, such as edge finishing and sewing, are time-consuming in the production process of clothing products and also impose a significant economic burden. Moreover, clothing products with edge finishing or edge sewing have a thicker fabric at that part, resulting in a step. In undergarments such as foundation garments, when an outerwear is worn over it, the step appears convex on the outerwear, damaging the appearance. Clothing using polyurethane elastic yarns includes many products that directly fit the body, such as foundation garments and panty stockings, and there is also a problem that the thickened edge reduces the wearing comfort.

[0005] In order to solve the above problems related to the edge finishing and sewing of clothing using polyurethane elastic yarns, in recent years, in the field of foundation garments such as bras, girdles, and body suits, where fashion is advancing, a manufacturing method of clothing products with so-called raw-edge openings has been studied, in which the edge finishing and sewing of the cut part are not performed, so that the line of the undergarment does not appear on the outerwear.

[0006] For example, there has been proposed a clothing using a fabric that does not require edge finishing, which is a warp knitted fabric with a 1×1 knitting structure in which an inelastic yarn and an elastic yarn run side by side, and at each knitting needle, at least one of the inelastic yarn and the elastic yarn is knitted by a closed stitch (see, for example, Patent Document 1). However, since the structure of the fabric is designed to make it difficult for the cut edges to fray, there are limitations to the fabric obtained by the fabric design, such as the fabric itself being thick, and the uses of the clothing are limited.

[0007] Also, there has been proposed a clothing having a raw-edge opening, which uses a low-melting-point polyurethane elastic yarn as a heat-sealing elastic yarn, knits other yarns by plating knitting, and uses a knitted fabric having a fraying prevention function that has been heat-set. (See Patent Document 2) However, low melting point polyurethane elastic yarn has a large reduction in physical properties due to heat during the setting process for shaping the fabric or product and the dyeing process. Therefore, when processed under high temperature conditions, the recovery of the fabric decreases. Furthermore, when subjected to more severe thermal processing conditions, the yarn of the polyurethane elastic yarn breaks. Therefore, products using this fabric have a problem that there are thermal restrictions on the processing conditions.

[0008] In addition, a polyurethane elastic yarn containing thermoplastic polyurethane as a heat-fusible elastic yarn has been proposed, but the adhesion performance has not yet reached a satisfactory level (see Patent Document 3).

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention provides a polyurethane elastic yarn having excellent heat setting properties and thermal adhesive strength in a wide temperature range while maintaining stretch characteristics (permanent strain rate and elongation), and a method for producing the same.

Means for Solving the Problems

[0011] In order to solve the above problems, the present invention employs any of the following means. (1) A polyurethane elastic yarn containing the following polyurethane polymer [A] and polyurethane polymer [B], The ratio of the polyurethane polymer [A] to the polyurethane polymer [B] is 1 to 30 parts by mass: 99 to 70 parts by mass, or 70 to 99 parts by mass: 30 to 1 part by mass, and the polyurethane elastic fiber has an exothermic peak (crystallization peak) measured by a differential scanning calorimeter (DSC) in the range of 110°C to 210°C, and the polyurethane elastic fiber has an exothermic amount of the exothermic peak of 3.0 J / g or more and 100 J / g or less. Polyurethane polymer [A]: a polymer diol A whose repeating unit in the main chain is ether or ester, a diisocyanate A whose main skeleton is aromatic or aliphatic, and a single low molecular weight diol A having 2 to 4 carbon atoms as a chain extender as starting materials to form a polyurethane polymer Polyurethane polymer [B]: the polymer diol A, the diisocyanate A, and a single low molecular weight diol B having 1 to 4 more carbon atoms than CA as a chain extender as starting materials to form a polyurethane polymer (2) The melting point MpA of the polyurethane polymer [A] measured by a differential scanning calorimeter (DSC) is 130 to 260°C, The melting point MpB of the polyurethane polymer [B] measured by a differential scanning calorimeter (DSC) is 10°C to 100°C lower than MpA, the polyurethane elastic fiber according to claim 1 (3) [A] is a polyurethane polymer polymerized in solution The polyurethane elastic fiber according to claim 1 or 2 (4) The polymer diol of [A] is polytetramethylene ether glycol (PTMG), the polyurethane elastic fiber according to any one of claims 1 to 3 (5) The following polyurethane polymer [A] and polyurethane polymer [B] are polymerized separately in solution, and then a method for producing a polyurethane elastic fiber by spinning a spinning dope prepared by mixing both polymerization solutions. Polyurethane polymer [A]: A polymer diol A in which the repeating unit of the main chain is ether or ester, A diisocyanate A in which the main skeleton is aromatic or aliphatic, A single low molecular weight diol A having 2 to 4 carbon atoms as a chain extender A polyurethane polymer using these as starting materials Polyurethane polymer [B]: The polymer diol A, The diisocyanate A, A single low molecular weight diol B having 1 to 4 more carbon atoms (CB) than the carbon number (CA) of the above as a chain extender A polyurethane polymer using these as starting materials

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a polyurethane elastic yarn having excellent heat setting properties in a wide temperature range and excellent thermal adhesive strength in a wide temperature range while maintaining the stretching properties (permanent strain rate and elongation), and a method for producing the same.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0014] The present invention will be described in more detail below.

[0015] The present invention contains the following polyurethane polymer [A] and polyurethane polymer [B] in a specific ratio and has specific heat generation characteristics. By controlling the respective chain extenders in the polyurethane polymer [A] and the polyurethane polymer [B], it is possible to provide a polyurethane elastic fiber having excellent heat setting properties in a wide temperature range and excellent thermal adhesive strength in a wide temperature range, which is not found in the prior art, and a method for producing the same.

[0016] [Polyurethane polymer [A]] The polyurethane polymer [A] used in the polyurethane elastic fiber of the present invention will be described.

[0017] The polyurethane polymer [A] used in the present invention is a polyurethane polymer starting from a polymer diol A whose repeating unit in the main chain is ether or ester, a diisocyanate A whose main skeleton is aromatic or aliphatic, and a single low molecular weight diol A having 2 to 4 carbon atoms as a chain extender.

[0018] Using a polymer diol, a diisocyanate, and a low molecular weight diol as a chain extender as starting materials means that the resulting polyurethane polymer has a structure derived from each component. That is, it defines the structure of the polyurethane polymer obtained using a polymer diol, a diisocyanate, and a low molecular weight diol as a chain extender as starting materials, and does not specify the raw materials themselves. Similarly, even when synthesizing with the same raw materials, the synthesis method is not particularly limited.

[0019] Hereinafter, when explaining the specific structure of the polyurethane polymers ([A] and [B]) used in the present invention, the case of synthesizing using a polymer diol and a diisocyanate as raw materials may be described as an example. However, as described above, it is for the convenience of specifying the partial structure of the polyurethane polymer and does not limit the raw materials or the production method.

[0020] [Polymer diol A] As the polymer diol A, those having a polyether-based skeleton in which the repeating unit of the main chain is ether or a polyester-based skeleton in which the repeating unit of the main chain is ester are preferable. In particular, from the viewpoint of imparting flexibility and elongation to the polyurethane elastic fiber, it is preferable to have a repeating unit of the main chain that can introduce a polyether-based partial structure into the polyurethane polymer.

[0021] Examples of the polymer diol that gives a polyether-based partial structure to the polyurethane polymer include polyethylene oxide, polyethylene glycol, derivatives of polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol (hereinafter abbreviated as PTMG), a copolymer of tetrahydrofuran (hereinafter abbreviated as THF) and 3-methyltetrahydrofuran (hereinafter abbreviated as 3M-PTMG), a modified PTMG that is a copolymer of THF and 2,3-dimethyl THF, a polyol having side chains disclosed in Japanese Patent No. 2615131, etc., and a random copolymer in which THF, ethylene oxide, and / or propylene oxide are irregularly arranged, etc. It may contain one or more structures derived therefrom as the repeating unit of the main chain.

[0022] Further, from the viewpoint of obtaining abrasion resistance and light resistance as the polyurethane elastic fiber, as the polymer diol that can introduce a polyester-based partial structure into the polyurethane polymer, polyester-based diols such as butylene adipate, polycaprolactone diol, and polyester polyol having side chains disclosed in JP-A-61-26612, etc., and polycarbonate diol disclosed in Japanese Patent Publication No. 2-289516, etc. are preferably mentioned.

[0023] Among these polymer diols A, polytetramethylene ether glycol is preferable because of its good stretch characteristics (permanent strain rate and elongation) and economic efficiency.

[0024] Such polymer diols may be only one kind or may contain two or more kinds.

[0025] From the viewpoint of obtaining elongation at break, strength, heat resistance, etc. when made into a thread, the molecular weight of the polymer diol is preferably 1000 or more and 8000 or less, more preferably 1500 or more and 6000 or less. By setting the molecular weight of the polymer diol within this range, it becomes possible to obtain an elastic thread excellent in elongation at break, strength, elastic resilience, and heat resistance. The molecular weight of the partial structure can be adjusted by selecting the number average molecular weight of the polymer diol A as the raw material.

[0026] [Diisocyanate A] As the diisocyanate A, those having an aromatic or aliphatic main skeleton are preferred. Here, the aliphatic skeleton shall mean a linear aliphatic and / or alicyclic skeleton.

[0027] In particular, as such diisocyanate A, those having an aromatic main skeleton such as diphenylmethane diisocyanate (hereinafter abbreviated as MDI), tolylene diisocyanate, 1,4-diisocyanate benzene, xylylene diisocyanate, 2,6-naphthalene diisocyanate, etc. are suitable for obtaining a polyurethane polymer that gives a polyurethane elastic thread with particularly high heat resistance and strength.

[0028] The aliphatic diisocyanate having an aliphatic main skeleton is particularly effective in suppressing the yellowing of the polyurethane elastic thread. Among the aliphatic diisocyanates having an aliphatic main skeleton, those having an alicyclic main skeleton such as methylene bis(cyclohexyl isocyanate) (hereinafter referred to as H12MDI), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotoluene diisocyanate, octahydro 1,5-naphthalene diisocyanate, etc. are also preferred.

[0029] These diisocyanates may be used alone or in combination of two or more.

[0030] [Chain extender] A chain extender is a compound having at least two active hydrogen groups, and is used to efficiently increase the molecular weight of a polyurethane polymer composed of a polymer diol and a diisocyanate in the polymerization process of the polyurethane polymer. As such a chain extender, those having a relatively small molecular weight are preferable from the viewpoints of reactivity and enhancing the crystallinity and rigidity of the hard segment. More specifically, they are low molecular weight diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1-methyl-1,2-ethanediol.

[0031] A single low molecular weight diol A having 2 to 4 carbon atoms is used as the chain extender for the polyurethane polymer [A] of the present invention. The low molecular weight diol A uses any one of ethylene glycol, 1,3-propanediol, and 1,4-butanediol as the chain extender. The reason for using the low molecular weight diol A is that by combining it with the polyurethane polymer [B] using the low molecular weight diol B described later in a specific blending amount, the exothermic peak (crystallization peak) measured by a differential scanning calorimeter (DSC) of the polyurethane elastic fiber can be set in the range of 110°C to 210°C, and the exothermic amount of the exothermic peak can be made 3.0 J / g or more.

[0032] [Polyurethane polymer [B]] The polyurethane polymer [B] in the present invention will be described. By containing the polyurethane polymer [B] having a specific structure within a specific range, it becomes possible to inhibit the progress of crystallization of the hard segment of the polyurethane polymer [A] in the process of producing the polyurethane elastic yarn, as will be described in detail later, and it is considered that the effects of the present invention can be obtained. From the viewpoint of compatibility with the hard segment of the polyurethane polymer [A], the polyurethane polymer [B] used in the present invention uses a polymer diol A having the same repeating unit in the main chain as the polyurethane polymer [A] and a diisocyanate A having the same repeating unit in the main chain as the polyurethane polymer [A], and it is preferable to use a single low molecular weight diol B having 1 to 4 more carbon atoms CB than CA as a chain extender as a starting material.

[0033] Regarding the structure, it is presumed that the effects of the present invention can be obtained by containing polyurethane polymer [A] and polyurethane polymer [B] having such a relationship in a ratio of 1 to 30 parts by mass: 99 to 70 parts by mass, or 70 to 99 parts by mass: 30 to 1 part by mass. That is, taking the case where the ratio of polyurethane polymer [A] to polyurethane polymer [B] is 70 to 99 parts by mass: 30 to 1 part by mass as an example, by blending a small amount of polyurethane polymer [B] having the above structural relationship, when the hard segments of polyurethane polymer [A] gather to form partial crystal parts during spinning, it becomes easier for polyurethane polymer [B] to enter between the hard segments of polyurethane polymer [A], and the generation of crystals in which the hard segments have gathered (hereinafter, may be abbreviated as hard segment crystals) is inhibited. The polyurethane elastic yarn whose crystal formation is inhibited in this way has good thermoplasticity at a relatively low temperature of 110°C to 210°C, and can significantly improve the heat setting property and heat adhesiveness. In the above description, the case where the ratio of polyurethane polymer [A] to polyurethane polymer [B] is 70 to 99 parts by mass: 30 to 1 part by mass was described as an example, but it is considered that the same effect can be obtained for the case where the ratio is reversed for the same reason. More preferably, the ratio of polyurethane polymer [A] to polyurethane polymer [B] is 70 to 99 parts by mass: 30 to 1 part by mass. Also, when polyurethane polymer [A] and polyurethane polymer [B] are in a ratio of 1 to 30 parts by mass: 99 to 70 parts by mass, it is preferable that the ratio of polyurethane polymer [A] to polyurethane polymer [B] is in the range of 2 to 20 parts by mass: 98 to 80 parts by mass, and more preferably in the range of 3 to 15 parts by mass: 97 to 85 parts by mass. Further, when the ratio of polyurethane polymer [A] to polyurethane polymer [B] is 70 to 99 parts by mass: 30 to 1 part by mass, it is more preferable that the ratio of polyurethane polymer [A] to polyurethane polymer [B] is in the range of 80 to 98 parts by mass: 20 to 2 parts by mass, and even more preferably in the range of 85 to 97 parts by mass: 15 to 3 parts by mass.Here, the term "heat adhesiveness" refers to the function in which polyurethane elastic yarns adhere to each other and / or polyurethane elastic yarns adhere to other interlaced yarns by heat when a fabric containing polyurethane elastic yarns is heat-treated. This function is very important for preventing yarn breakage and / or fraying in pantyhose and free-cut products.

[0034] It is desirable that the crystallization point of the polyurethane polymer [B] in the present invention be below the boiling point of the solvent of the polyurethane polymer [A] used in yarn production. In that case, the polyurethane polymer [B] does not crystallize during yarn production, and the crystallization of the hard segments of the polyurethane polymer [A] can be more effectively inhibited. The crystallization point of the polyurethane polymer [B] is preferably in the range of 110°C to 210°C. If the crystallization point is less than 110°C, depending on the addition amount, it may cause deterioration of the spinnability, and it is not preferable because the polyurethane elastic yarn is likely to become sticky when wound. Conversely, if the crystallization point exceeds 210°C, good heat adhesiveness cannot be obtained unless the heat treatment temperature is increased, so it is not preferable. From such a viewpoint, the crystallization point of the polyurethane polymer [B] is more preferably in the range of 110°C to 160°C. Also, when the heat generation amount of the heat generation peak at the crystallization point is 3.0 J / g or more and 100 J / g or less, good heat adhesiveness is exhibited, and 8.0 J / g or more and 80 J / g or less is more preferable. Such a crystallization point can be measured by a differential scanning calorimeter (DSC) using a cast film made from the polyurethane polymer [B] as a sample. A general-purpose DSC can be used, and the scanning rate is preferably 1°C / min to 10°C / min.

[0035] From the viewpoints of obtaining good spinnability, well-balanced mechanical properties, heat adhesiveness, and heat resistance, in the polyurethane elastic yarn of the present invention, the content of the polyurethane polymer [B] is preferably in the range of 1.0% by weight or more and 30% by weight or less, or in the range of 70% by weight or more and 99% by weight or less.

[0036] When the content of polyurethane polymer [B] is relatively less than that of polyurethane polymer [A], if the proportion of polyurethane polymer [B] in the polyurethane elastic yarn is less than 1.0% by weight, sufficient thermal adhesiveness cannot be obtained. If it exceeds 30% by weight, the spinnability and mechanical properties will deteriorate, which is not preferable.

[0037] When the content of polyurethane polymer [B] is relatively more than that of polyurethane polymer [A], it is also preferable that the content of polyurethane polymer [B] is in the range of 99% by weight or less and 70% by weight or more. In that case, conversely to the above, when the hard segments of polyurethane polymer [B] tend to aggregate during yarn production, it becomes easier for polyurethane polymer [A] to penetrate between the polyurethane polymers [B]. In this way, polyurethane polymer [A] does not crystallize during yarn production and functions as a component that inhibits the crystallization of the hard segments of polyurethane polymer [B].

[0038] [Melting point of polyurethane polymer] The melting point MpA of the polyurethane polymer [A] in the present invention measured by a differential scanning calorimeter (DSC) is preferably 130 to 260°C. When it is in this range, good compatibility with the processing temperature of other blended fibers can be obtained, and the good thermal adhesiveness, which is the object of the present invention, can be exhibited. Specifically, various polyester fibers with high processing temperatures such as dyeing can be thermally adhered to polypropylene fibers with low processing temperatures such as heat setting. And the melting point MpB of the polyurethane polymer [B] measured by a differential scanning calorimeter (DSC) is preferably 10°C to 100°C lower than MpA. When it is in this range, the good thermal adhesiveness, which is the object of the present invention, can be exhibited both when the ratio of polyurethane polymer [A] to polyurethane polymer [B] is 1 to 30 parts by mass: 99 to 70 parts by mass and when it is 70 to 99 parts by mass: 30 to 1 part by mass.

[0039] It should be noted that these contents are preferably tested in advance according to the application and determined appropriately.

[0040] The method of incorporating 1.0 to 30% by weight of the polyurethane polymer [B] into the polyurethane elastic fiber is exemplified as follows. The polyurethane polymer [B] is added to a spinning dope containing the polyurethane polymer [A] before spinning and using N,N-dimethylformamide, N,N-dimethylacetamide, etc. as solvents, and stirring and mixing are carried out so that it is uniformly dispersed or dissolved without streaks. Alternatively, the polyurethane polymer [B] may be uniformly dispersed or dissolved in a similar solvent in advance and then mixed with the polyurethane polymer [A] solution.

[0041] And the spinning dope containing the aforementioned polyurethane polymer [A] and solvent is preferably a polyurethane polymer in which [A] is polymerized in the solvent, that is, polymerized in solution. Also, it is preferable that the aforementioned polyurethane polymer [B] is also a polyurethane polymer in which [B] is polymerized in the solvent, that is, polymerized in solution. The most preferable case is when both the polyurethane polymers [A] and [B] are polymerized in solution and mixed without undergoing drying by solvent removal or chipping. The melting point and crystallization point of the polyurethane polymers [A] and [B] are controlled according to established methods. That is, the main factor for control is the ratio of diisocyanate to polymer diol. Increasing the ratio of diisocyanate to polymer diol tends to increase the melting point and crystallization point.

[0042] [Thermal properties of polyurethane elastic fiber] The polyurethane elastic fiber of the present invention has an exothermic peak (crystallization peak) measured by a differential scanning calorimeter (DSC) in the range of 110°C or higher and 210°C or lower, and the heat generation amount of this exothermic peak is 3.0 J / g or higher and 100 J / g or lower. The exothermic peak in the range of 110°C or higher and 210°C or lower is derived from the heat generation when the hard segments in the polyurethane elastic fiber aggregate to form crystals. In the polyurethane elastic fiber of the present invention, the aggregation of hard segments during fiber production is inhibited by the polyurethane polymer [B], so almost no hard segment crystals are formed at the end of fiber production. The DSC measurement is carried out by finely cutting the sample, pressing it in a small metal pan to make a measurement sample, and slowly heating it at 3°C / min. Therefore, when a polyurethane elastic fiber in which hard segment crystallization is inhibited during fiber production is measured by DSC, a large crystallization peak is observed due to the temperature rise.

[0043] [Molecular weight of polyurethane] In the present invention, from the viewpoint of obtaining fibers with high durability and strength, the molecular weight of the polyurethane preferably ranges from 30,000 to 150,000 in terms of number average molecular weight. The molecular weight in the present invention is the molecular weight in terms of polystyrene measured by GPC.

[0044] [Other components] The polyurethane elastic yarn of the present invention may contain various stabilizers, pigments, etc. For example, hindered phenol-based agents such as BHT and "Sumilizer" (registered trademark) GA-80 manufactured by Sumitomo Chemical Co., Ltd., benzotriazole-based and benzophenone-based agents such as various "Tinuvin" (registered trademark) manufactured by Ciba-Geigy, phosphorus-based agents such as "Sumilizer" (registered trademark) P-16 manufactured by Sumitomo Chemical Co., Ltd., various hindered amine-based agents, various pigments such as iron oxide and titanium oxide, inorganic substances such as zinc oxide, cerium oxide, magnesium oxide, calcium carbonate, and carbon black, fluorine-based or silicone-based resin powders, and lubricants such as silicone and mineral oil, and various antistatic agents such as cerium oxide, betaine, and phosphate are preferably included, and it is also preferable that these are included in a state of being bound to the polymer. And in particular, to further enhance the durability against light and various nitrogen oxides, etc., for example, it is also preferable to include nitrogen oxide scavengers such as HN-150 manufactured by Nippon Hydrazine Co., Ltd., thermal oxidation stabilizers such as "Sumilizer" (registered trademark) GA-80 manufactured by Sumitomo Chemical Co., Ltd., and light stabilizers such as "Sumisorb" (registered trademark) 300#622 manufactured by Sumitomo Chemical Co., Ltd.

[0045] [Method for manufacturing polyurethane elastic yarn] The method for manufacturing the polyurethane elastic yarn of the present invention is a method for manufacturing a polyurethane elastic yarn in which the following polyurethane polymer [A] and polyurethane polymer [B] are polymerized separately in a solution and then the two polymerization solutions are mixed to prepare a spinning dope for spinning. · Polyurethane polymer [A]: A polyurethane polymer using polymer diol A whose repeating unit in the main chain is ether or ester, diisocyanate A whose main skeleton is aromatic or aliphatic, and a single low-molecular-weight diol A having 2 to 4 carbon atoms as a chain extender as starting materials · Polyurethane polymer [B]: A polyurethane polymer using the polymer diol A, the diisocyanate A, and a single low-molecular-weight diol B having 1 to 4 more carbon atoms than CA as a chain extender as starting materials.

[0046] In the present invention, a polyurethane polymer [B] is added to a spinning dope of a polyurethane polymer [A] and then spun. From the viewpoint of stabilizing the polymerization, it is preferable to prepare the polyurethane polymer [A] in advance and then add the polyurethane polymer [B] thereto. Further, the method for producing the polyurethane polymer [A], which is the solute of the solution, may be either a melt polymerization method or a solution polymerization method, or any other method. However, a solution polymerization method is more preferable. In the case of the solution polymerization method, generation of foreign matters such as gels in the polyurethane polymer is less, spinning is easier, and it is easy to obtain a low-denier polyurethane elastic fiber. Also, of course, in the case of solution polymerization, there is an advantage that the operation of making a solution can be omitted.

[0047] Particularly preferred polyurethane polymers for the present invention include those synthesized using PTMG having a molecular weight of 1500 or more and 6000 or less as a polymer diol, MDI as a diisocyanate, and at least one of ethylene glycol (hereinafter abbreviated as EG), 1,3-propanediol, and 1,4-butanediol as a chain extender.

[0048] [Solvent] The polyurethane polymer can be obtained, for example, by synthesizing using the aforementioned raw materials in solvents such as dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), or solvents mainly composed of these. For example, a so-called one-shot method in which each raw material is charged and dissolved in such a solvent, heated to an appropriate temperature, and reacted to obtain a polyurethane polymer, or a method in which a polymer diol and a diisocyanate are first melt-reacted, and then the reaction product is dissolved in a solvent and reacted with the aforementioned chain extender to obtain a polyurethane polymer, etc. are adopted as particularly preferred methods.

[0049] [Catalyst] In addition, when synthesizing such a polyurethane polymer, it is also preferable to use one or a mixture of two or more catalysts such as amine-based catalysts and organometallic catalysts.

[0050] Examples of amine catalysts include N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N,N’,N’-tetramethylethylenediamine, N,N,N’,N’-tetramethyl-1,3-propanediamine, N,N,N’,N’-tetramethylhexanediamine, bis-2-dimethylaminoethyl ether, N,N,N’,N’,N’-pentamethyldiethylenetriamine, tetramethylguanidine, triethylenediamine, N,N’-dimethylpiperazine, N-methyl-N’-dimethylaminoethyl-piperazine, N-(2-dimethylaminoethyl)morpholine, 1-methylimidazole, 1,2-dimethylimidazole, N,N-dimethylaminoethanol, N,N,N’-trimethylaminoethylethanolamine, N-methyl-N’-(2-hydroxyethyl)piperazine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N-dimethylaminohexanol, triethanolamine, and the like.

[0051] Examples of organometallic catalysts include tin octanoate, dibutyltin dilaurate, lead dibutyl octanoate, and the like.

[0052] The concentration of the polyurethane polymer in the solution of the thus obtained polyurethane polymer is usually preferably in the range of 30% by mass or more and 80% by mass or less.

[0053] [Spinning method] By spinning the spinning dope configured as described above, for example, by dry spinning, wet spinning, or melt spinning, and winding it up, the polyurethane elastic fiber used in the present invention can be obtained. Among them, dry spinning is preferred from the viewpoint of being able to stably spin at all finenesses from fine to thick. And the dry spinning method is not particularly limited, and spinning conditions suitable for the desired properties and spinning equipment may be appropriately selected for spinning.

[0054] For example, since the permanent strain rate and stress relaxation characteristics of the polyurethane elastic yarn used in the present invention are particularly susceptible to the influence of the speed ratio between the godet roller and the winder, it is preferably determined as appropriate according to the intended use of the yarn. That is, from the viewpoint of obtaining a polyurethane elastic yarn having a desired permanent strain rate and stress relaxation, it is preferable to wind the speed ratio between the godet roller and the winder in the range of 1.15 or more and 1.65 or less. Further, since the strength of the polyurethane elastic yarn can be improved by increasing the spinning speed, it is preferable to take a spinning speed of 450 m / min or more in order to achieve a practically suitable strength level. Furthermore, considering the point of industrial production, about 450 to 1000 m / min is preferable.

[0055] The fiber structure of the present invention containing the polyurethane elastic yarn described above, or the polyurethane elastic yarn obtained by the production method described above, is excellent in processability such as stretch characteristics and heat setting. Therefore, even when it is used to make a thin fabric, sufficient stretch characteristics and aesthetic properties can be obtained, so that a high-class and excellent-looking clothing can be obtained. Such features can be remarkably obtained in knitted fabrics. In particular, the circular knitted fabric of the present invention using the polyurethane elastic yarn described above, or the polyurethane elastic yarn obtained by the production method described above, can be preferably applied to uses that pursue aesthetic properties by taking advantage of its body fit when used as clothing, such as underwear, stockings, tights, etc.

[0056] The fineness, number of single filaments, cross-sectional shape, etc. of the polyurethane elastic yarn used in the present invention are not particularly limited. For example, it may be a monofilament composed of 1 single filament, or a multifilament composed of a plurality of single filaments. The cross-sectional shape of the yarn may be circular or flat.

Examples

[0057] The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, the number of evaluations n was carried out with n = 3.

[0058] [Strength, Stress Relaxation, Permanent Strain Rate, and Elongation of Polyurethane Elastic Yarn] The strength, stress relaxation, permanent strain rate, and elongation of the polyurethane elastic yarn were measured by conducting a tensile test on the sample yarn using an Instron 4502 type tensile testing machine.

[0059] These are defined as follows. That is, a 5 cm (L1) sample was repeatedly stretched 5 times to 300% elongation at a tensile speed of 50 cm / min. The stress at the 5th time was taken as (G1). Next, the 300% elongation was maintained for 30 seconds as it was. The stress after holding for 30 seconds was taken as (G2). Next, the elongation was allowed to recover, and the length of the sample yarn when the stress became 0 was taken as (L2). Furthermore, the sample yarn was stretched until it broke at the 6th time. The stress at the time of breakage was taken as (G3), and the length of the sample yarn at the time of breakage was taken as (L3). The tensile test was conducted 5 times and evaluated based on the average value.

[0060] Hereinafter, each of the above characteristics was calculated by the following formula.

[0061] Strength = (G3) Stress relaxation = 100 × ((G1) - (G2)) / (G1) Permanent strain rate = 100 × ((L2) - (L1)) / (L1) Elongation = 100 × ((L3) - (L1)) / (L1).

[0062] [Heat Setting Property] The sample yarn (length = L5) was stretched 100% (length = 2 × (L5)). It was processed at a predetermined temperature for 1 minute in this state. Furthermore, it was left at room temperature for 1 day while still in the stretched state. Next, the stretched state of the sample yarn was released, and it was left at room temperature for 1 day. Then, the length (L6) was measured. The heat setting property is given by the following formula. A higher value of the heat setting property indicates better performance.

[0063] Heat setting property = 100 × ((L6) - (L5)) / (L5).

[0064] [Exothermic Peak Temperature, Heat Release Amount] Measured by a differential scanning calorimeter (2920MDSC manufactured by TA Instruments Japan Co., Ltd.) connected to TA5000 manufactured by TA Instruments Japan Co., Ltd. Approximately 8 mg of the cut sample yarn was collected in an aluminum pan, covered with a cover and crimped to form a sample. After setting the sample and reference at predetermined positions in the cell, the measurement was carried out under a nitrogen gas flow rate of 40 Nml / min. The temperature was raised from room temperature to 50 °C at a heating rate (scanning rate) of 3 °C / min, held at this temperature for 5 minutes, and then further raised to 300 °C. The exothermic peak temperature and exothermic amount resulting from the crystallization of the sample yarn recorded at this time were measured and designated as the exothermic peak temperature (unit: °C) and exothermic amount (unit: J / g), respectively.

[0065] [Thermal adhesiveness] Two test yarns 1 sampled at a length of approximately 10 cm (both ends are tied and fixed) were intertwined at the center as shown in Fig. 1 and fixed to the metal frame 2 at intervals of 1 cm (a). In a state where each test yarn 1 was stretched so as to have an elongation of 30%, it was treated at a predetermined dry heat temperature for 1 minute (b). After the treatment, the sample was removed from the metal frame 2 so that only the adhesive part 3 was in contact with the two (c), and one end of each test yarn was set in the upper and lower chucks of the testing machine using an Instron 4502 type tensile testing machine. The maximum stress when the tensile adhesive part was peeled off at 50 cm / min was measured and divided by the fineness of the polyurethane elastic fiber sample.

[0066] [Example 1] As the polyurethane polymer [A], a DMAC solution (35% by mass) of polyurethane polymer A1 composed of PTMG with a molecular weight of 2000 (denoted as PTMG2000 in the table; the same applies hereinafter), MDI, ethylene glycol (EG), and 1-butanol as a terminal blocking agent was prepared. Next, as an antioxidant, a polyurethane solution (manufactured by DuPont "Metacol" (registered trademark) 2462D) produced by the reaction of t-butyldiethanolamine and methylene-bis-(4-cyclohexylisocyanate) and a condensation polymer of p-cresol and divinylbenzene (manufactured by DuPont "Metacol" (registered trademark) 2390D) were mixed at a ratio of 2:1 (by mass), and an antioxidant DMAc solution (concentration 35% by mass) was prepared. 96 parts by mass of the DMAc solution of the polyurethane polymer and 4 parts by mass of the antioxidant solution were mixed to obtain a polymer solution pu1.

[0067] Next, as the polyurethane polymer [B], the thermoplastic polyurethane "Pandex" (registered trademark) T-8175N (polyurethane polymer B1) manufactured by DIC Covestro was dissolved in DMAc to obtain a 35% by mass polymer solution tp1.

[0068] The polymer solutions pu1 and tp1 were uniformly mixed at 96.5% by mass and 3.5% by mass to obtain a spinning solution P1. This was dry-spun at a speed of 720 m / min with a speed ratio of 1.3 between the godet roller and the winder to obtain a 200 g wound body of polyurethane elastic yarn PU113 with a fineness of 20 dtex, 1 filament, and a content of polyurethane polymer B1 of 3.0% by mass.

[0069] For the obtained polyurethane elastic yarn, the heat generation peak heat quantity, strength, stress relaxation, permanent strain rate, elongation, heat setting property, and heat adhesiveness were measured. The composition and results are shown in Table 1.

[0070] [Example 2] The polymer solutions pu1 and tp1 were uniformly mixed at 93.0% by mass and 7.0% by mass to obtain a spinning solution P2. This was dry-spun at a speed of 720 m / min with a speed ratio of the godet roller to the winder of 1.3 to obtain a 200 g wound body of a polyurethane elastic yarn PU116 having 20 decitex, 1 filament, and a polyurethane polymer B1 content of 6.0% by mass. For the obtained polyurethane elastic yarn, the calorific value at the exothermic peak, strength, stress relaxation, permanent strain rate, elongation, heat setting property, and heat adhesiveness were measured. The composition and results are shown in Table 1.

[0071] [Example 3] As the polyurethane polymer [B], a DMAC solution (25% by mass) tp2 of a polyurethane polymer B2 obtained by polymerizing PTMG with a molecular weight of 2000, MDI, butylene glycol, and 1-butanol as a terminal blocking agent in a DMAc solution was prepared.

[0072] The polymer solutions pu1 and tp2 were uniformly mixed at 92.0% by mass and 8.0% by mass to obtain a spinning solution P3, which was dry-spun in the same manner as in Example 1 to obtain a 200 g wound body of a polyurethane elastic yarn PU126 having 20 decitex, 1 filament, and a polyurethane polymer B2 content of 6.0% by mass. The composition and evaluation results are shown in Table 1.

[0073] [Example 4] As the polyurethane polymer [B], a DMAC solution (35% by mass) tp2α of a polyurethane polymer B2 obtained by polymerizing PTMG with a molecular weight of 2000, MDI, butylene glycol, and 1-butanol as a terminal blocking agent in a DMAc solution was prepared.

[0074] The polymer solutions pu1 and tp2α were uniformly mixed at 6.0% by mass and 94.0% by mass to obtain a spinning solution P4, which was dry-spun in the same manner as in Example 1 to obtain a 200 g wound body of a polyurethane elastic yarn PU226 having 20 decitex, 1 filament, and a polyurethane polymer B2 content of 94.0% by mass. The composition and evaluation results are shown in Table 1.

[0075] [Example 5] As the polyurethane polymer [B], a DMAC solution (35% by mass) tp3 of thermoplastic polyurethane B3 was prepared by polymerizing PTMG with a molecular weight of 2000, MDI, 1,6 - hexanediol, and 1 - butanol as a terminal blocking agent in a DMAc solution.

[0076] The polymer solutions pu1 and tp3 were uniformly mixed at 94.0% by mass and 6.0% by mass to obtain a spinning solution P5, which was dry - spun in the same manner as in Example 1 to obtain a 200 - g wound bobbin of a polyurethane elastic yarn PU326 with a fineness of 20 decitex, 1 filament, and a polyurethane polymer B2 content of 6.0% by mass. The composition and evaluation results are shown in Table 1.

[0077] [Example 6] As the polyurethane polymer [A], a DMAC solution (35% by mass) tp2α of polyurethane polymer B2 was used, and as the polyurethane polymer [B], a DMAC solution (35% by mass) tp3 of polyurethane polymer B3 was used. The polymer solutions tp2α and tp3 were uniformly mixed at 94.0% by mass and 6.0% by mass to obtain a spinning solution P6, which was dry - spun in the same manner as in Example 1 to obtain a 200 - g wound bobbin of a polyurethane elastic yarn PU426 with a fineness of 20 decitex, 1 filament, and a polyurethane polymer B2 content of 6.0% by mass. The composition and evaluation results are shown in Table 1.

[0078] [Example 7] The polymer solutions pu1 and tp2 were uniformly mixed at 84.0% by mass and 16.0% by mass to obtain a spinning solution P3'. This was dry - spun in the same manner as in Example 3 to obtain a 200 - g wound bobbin of a polyurethane elastic yarn PU1212 with a fineness of 20 decitex, 1 filament, and a polyurethane polymer B2 content of 12.0% by mass. The composition and evaluation results are shown in Table 1. Also, the DSC measurement results (DSC chart) are shown in Figure 2 together with Comparative Example 1. It is shown that the heat - release amount of the exothermic peak with a peak temperature in the range of 110°C or higher and 210°C or lower is 27.19 J / g (recorded as 27.2 J / g considering significant figures in Table 1).

[0079] [Comparative Example 1] The polymer solution pu1 was dry-spun in the same manner as in Example 1 to obtain a 200 g wound body of polyurethane elastic yarn PU100 with 20 decitex and 1 filament. The composition and various evaluation results are shown in Table 1. Also, the DSC measurement results (DSC chart) are shown in Figure 2 together with those of Example 7. It is shown that the heat generation amount of the exothermic peak with the peak temperature in the range of 110 °C or higher and 210 °C or lower is 1.464 J / g (recorded as 1.5 J / g in Table 1 considering significant figures).

[0080] [Comparative Example 2] The polymer solution tp2α was dry-spun in the same manner as in Example 1 to obtain a 200 g wound body of polyurethane elastic yarn PU100 with 20 decitex and 1 filament. The composition and various evaluation results are shown in Table 1.

[0081] [Comparative Example 3] A DMAC solution (35% by weight) of a polyurethane urea polymer composed of PTMG with a molecular weight of 1800, MDI, ethylenediamine, and diethylamine as a terminal blocking agent was prepared. Next, as an antioxidant, a polyurethane solution produced by the reaction of t-butyldiethanolamine and methylene-bis-(4-cyclohexylisocyanate) (“Metaclor” (registered trademark) 2462D manufactured by DuPont) and a condensation polymer of p-cresol and divinylbenzene (“Metaclor” (registered trademark) 2390D manufactured by DuPont) were mixed at a ratio of 2:1 (mass ratio) to prepare an antioxidant DMAc solution (concentration 35% by mass). 96 parts by mass of the DMAc solution of the polyurethane urea polymer and 4 parts by mass of the antioxidant solution were mixed to obtain a polymer solution pu3.

[0082] The polymer solution pu3 was dry-spun in the same manner as in Example 1 to obtain a 200 g wound body of polyurethane elastic yarn PU500 with 20 decitex and 1 filament. The composition and various evaluation results are shown in Table 1.

[0083] [Comparative Example 4] Thermoplastic polyurethane “Pandex” (registered trademark) T-8180 manufactured by DIC Covestro was dissolved in DMAc to obtain a 30% by mass polymer solution tp3.

[0084] The polymer solutions pu2 and tp3 were uniformly mixed at 93.0% by mass and 7.0% by mass to obtain a spinning solution PX4.

[0085] This was dry-spun in the same manner as in Example 1 to obtain a 200 g wound bobbin of a polyurethane elastic yarn PU536 having a fineness of 20 decitex, 1 filament, and a polyurethane polymer B3 content of 6.0% by mass. The composition and various evaluation results are shown in Table 1.

[0086] [Comparative Example 5] A DMAc solution (30% by weight) of a thermoplastic polyurethane elastomer (product name E790PNAT, adipate-based) (polyurethane polymer B4) manufactured by Nippon Milacron Co., Ltd. was adjusted by stirring at 60 °C to obtain a polymer solution tp4.

[0087] The polymer solutions pu1 and tp4 were uniformly mixed at 93.0% by mass and 7.0% by mass to obtain a polymer solution PX5. This was dry-spun in the same manner as in Example 1 to obtain a 200 g wound bobbin of a polyurethane elastic yarn PU146 having a fineness of 20 decitex, 1 filament, and a polyurethane polymer B4 content of 6.0% by mass. The composition and various evaluation results are shown in Table 1.

[0088] [Comparative Example 6] The polymer solutions pu2 and tp4 were uniformly mixed at 93.0% by mass and 7.0% by mass to obtain a spinning solution PX6. This was dry-spun in the same manner as in Example 1 to obtain a 200 g wound bobbin of a polyurethane elastic yarn PU546 having a fineness of 20 decitex, 1 filament, and a polyurethane polymer B4 content of 6.0% by mass. The composition and various evaluation results are shown in Table 1.

[0089]

Table 1-1

[0090]

Table 1-2

Claims

1. A polyurethane elastic fiber containing the following polyurethane polymer [A] and polyurethane polymer [B], wherein the ratio of the polyurethane polymer [A] to the polyurethane polymer [B] is 1 to 30 parts by mass: 99 to 70 parts by mass, or 70 to 99 parts by mass: 30 to 1 part by mass, the exothermic peak (crystallization peak) measured by a differential scanning calorimeter (DSC) of the polyurethane elastic fiber is in the range of 110°C to 210°C, and the heat of exotherm of the exothermic peak is 3.0 J / g or more and 100 J / g or less. A polyurethane elastic fiber. Polyurethane polymer [A]: A polymer diol A in which the repeating unit of the main chain is ether or ester, A diisocyanate A in which the main skeleton is aromatic or aliphatic, A single low molecular weight diol A having 2 to 4 carbon atoms as a chain extender A polyurethane polymer using as starting materials Polyurethane polymer [B]: The polymer diol A, The diisocyanate A, A single low molecular weight diol B having 1 to 4 more carbon atoms (CB) than CA as a chain extender A polyurethane polymer using as starting materials

2. The melting point M pA of the polyurethane polymer [A] measured by a differential scanning calorimeter (DSC) is 130 to 260°C, The melting point M pB of the polyurethane polymer [B] measured by a differential scanning calorimeter (DSC) is 10°C to 100°C lower than M pA. The polyurethane elastic fiber according to Claim 1.

3. The polymer diol of [A] is polytetramethylene ether glycol (PTMG). The polyurethane elastic fiber according to Claim 1 or 2.

4. After polymerizing the following polyurethane polymer [A] and polyurethane polymer [B] separately in solution, A method for producing a polyurethane elastic fiber, which comprises spinning a spinning dope prepared by mixing both polymerization solutions to produce the polyurethane elastic fiber according to any one of Claims 1 to 3. Polyurethane polymer [A]: A polymer diol A in which the repeating unit of the main chain is ether or ester, A diisocyanate A in which the main skeleton is aromatic or aliphatic, A single low molecular weight diol A having 2 to 4 carbon atoms as a chain extender A polyurethane polymer using as starting materials Polyurethane polymer [B]: The polymer diol A, The diisocyanate A, A single low molecular weight diol B having a carbon number (CB) that is 1 to 4 more than CA as a chain extender A polyurethane polymer using as starting materials

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