POLYURETHANE ELASTIC YARN AND METHOD OF MANUFACTURING THE SAME

Abstract

To provide a polyurethane elastic yarn that is superior in its unwinding and adhesion properties compared to a hot-melt adhesive, and to provide a method for manufacturing the same. The polyurethane elastic yarn comprises a diol or diisocyanate polymer as its principal structural component; and includes a polymer that includes, as its principal structural unit, a structural unit using an aromatic olefin and / or an aliphatic diolefin as a monomer, and is partially or fully hydrogenated.

Description

The present invention relates to an elastic polyurethane yarn with superior unwinding and heat-fusion adhesion properties, and a method of manufacturing the same; and further relates to an elastic polyurethane yarn that is ideal for producing a stretchable sheet that demonstrates good heat-fusion adhesion properties, even when processed with a high draft, and a method of manufacturing the same. Background of the Invention Elastic fibers, given their superior stretchability characteristics, are widely used in elastic garment applications, such as leggings, underwear, sportswear and the like, in hygienic applications (hygienic material applications), such as disposable diapers, sanitary napkins and the like, and in industrial material applications. In particular, in disposable hygiene applications, such as disposable diapers and sanitary napkins, there is a need for a design that allows for stretch to improve the fit and adaptability to the user. This is especially true with regard to diapers. Ref. 327970 disposable paper items: there have been a variety of innovations that allow for elastic stretch around the waist, legs, torso, etc. The use of a fabric with elastic stretch as the raw material itself has been considered, but this would be costly when used in disposable items. Therefore, a stretchable element in the form of a thread or band, in a stretched state, is typically applied to a non-stretchable member, such as a non-woven fabric, plastic film, or similar material, to allow the non-stretch element to stretch elastically, forming a stretchable sheet or an item with "gathering" properties (see, for example, JP2010-168717).The material that is bonded to the non-stretchable element to provide it with stretchability specifically uses an elastic polyurethane yarn in the form of a rubber band or belt-shaped yarn, and a hot-melt adhesive agent is used for bonding. On the other hand, patent document 2 teaches the use of various types of additives in an elastic polyurethane fiber in order to improve the heat fusion adhesion properties. Additionally, patent document 3 shows the application of an oil in order to achieve both unwinding and heat-fusion adhesion properties in an elastic polyurethane yarn. Publication of unexamined Japanese patent application 2002-35029 Publication of unexamined Japanese patent application 2010-168717 W016 / 143499 Brief Description of the Invention Problem solved by the present invention Regarding the polyurethane elastic yarn that has been conventionally used to provide elastic stretchability, as described in patent document 1, when the yarn is stretched and joined, the tensile strength of the polyurethane elastic yarn is high, resulting in strand breakage. When a large amount of hot-melt adhesive is used to prevent this, it can harden the material in exchange for reducing strand breakage, thus giving the manufactured product unsatisfactory stretchability. When attempting to improve the adhesion properties by heat fusion using additives, by applying the technology set out in patent document 2, there tends to be an adverse effect on the unwinding properties of the elastic polyurethane yarn, which tends to produce broken yarns in the manufacturing stage of the stretchable material. Also, in patent document 3, there is a need for an additional improvement in the adhesion properties by thermofusion. The objective is to provide an elastic polyurethane yarn, and a method of manufacturing it, to solve the problem areas indicated above in the prior art, which is superior in terms of the unwinding properties of the elastic polyurethane yarn and the adhesion properties of the hot melt adhesive material, which generates a stretchable sheet that demonstrates good adhesion properties, even when processed with a high draft, and which is suitable for producing hygienic products that have a soft feel to the touch. To solve the problem described above, the present invention uses any of the means set forth below: (1) An elastic polyurethane yarn comprising: a hydrocarbon resin (A) having a structure in which a polymer comprising, as main structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer, is partially or fully hydrogenated. (2) An elastic polyurethane yarn as set out above in (1), wherein: the hydrocarbon resin (A) has a structure wherein the polymer including structural units using an aromatic olefin as a monomer is partially hydrogenated or fully hydrogenated, and the aromatic olefin is indene and / or methylstyrene. (3) An elastic polyurethane yarn as set out above in (1) or (2), wherein: the hydrocarbon resin (A) has a structure wherein the polymer including structural units using an aliphatic diolefin as a monomer is partially or fully hydrogenated, and the aliphatic diolefin is isoprene and / or an isomer thereof. (4) An elastic polyurethane yarn as set out above in any of (1) to (3), wherein: the thermal softening point of the hydrocarbon resin (A) is not less than 70 °C nor greater than 140 °C. (5) An elastic polyurethane yarn as set forth above in any of (1) to (4), wherein: the hydrocarbon resin (A) is included in not less than 0.1% by mass and not more than 10% by mass. (6) An elastic polyurethane yarn as set out above in any of (1) to (5), wherein: the hydrocarbon resin (A) dissolves at not less than 10% by mass at 20°C with respect to a hydrocarbon oil (b) and is insoluble in DMAc and / or DMF. (7) A method for manufacturing an elastic polyurethane yarn wherein: after a hydrocarbon resin (a) having a structure in which a polymer including, as principal structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer is partially or fully hydrogenated is dissolved in a hydrocarbon oil (b), the hydrocarbon resin (a) is added so as to be in a range of not less than 0.1% by mass and not more than 10% by mass with respect to a solid polyurethane content in a polyurethane spinning solution, and is spun in solution. (8) A method for manufacturing an elastic polyurethane yarn according to claim (7), wherein: after the hydrocarbon resin (a) is dissolved to a concentration of not less than 5% in the hydrocarbon oil (b), it is added to a polyurethane spinning solution and spun in solution. Through the present invention, the elastic polyurethane yarn will be an elastic polyurethane yarn that has superior unwinding properties, good adhesion properties when using heat fusion, while maintaining superior elastic stretchability. Furthermore, this makes it possible to maintain superior adhesion properties when heat fusion is applied even when an oil is applied as a finishing material to the surface of the elastic polyurethane yarn. Therefore, a stretchable sheet can be produced from this elastic polyurethane yarn that exhibits good adhesion properties and can be stretched with low tension, even when processed with a high draft.Furthermore, when manufacturing a hygiene product, such as a disposable diaper, sanitary napkin, or similar item, this allows for manufacturing without broken threads, even at a faster production speed, and it also makes it possible to reduce costs by decreasing the amount of hot-melt adhesive. The retention rate of the hot-melt adhesive can be used as a metric for adhesion properties. Additionally, in hygiene products that use a reduced amount of hot-melt adhesive, there will be less hardening of the material caused by the adhesive, resulting in a softer feel and thus producing a product that is superior in comfort and fit. Detailed Description of the Invention The present invention will be described in more detail below. First, the polyurethane used in the present invention will be described. Insofar as the polyurethane used in the present invention includes a structure obtained using a diol and diisocyanate polymer as starting materials, there are no particular limitations regarding this. It should be noted that this specification of the starting material for the polyurethane structure is due to the fact that, in some cases, various different types of polymer diols and diisocyanates are used, and in such cases, it is difficult to describe the structure precisely using chemical names. That is, the starting materials are used to specify the structural units derived from them. Consequently, even a polyurethane obtained using a different starting material would not be excluded insofar as it has a structure that could be obtained using a diol and diisocyanate polymer as starting materials; there are no particular limitations regarding the method of synthesis.The polyurethane may be, for example, urea polyurethane, which uses, as a starting material, a diol polymer, a diisocyanate, and a low molecular weight diamine, or it may be a polyurethane which uses, as a starting material, a diol polymer, a diisocyanate, and a low molecular weight diol. In addition to these, it may be a urea polyurethane which uses, as a starting material, a compound having, within its molecules, amino and hydroxyl groups as chain-extending agents. Isocyanates and glycols that are polyfunctional, trifunctional, and higher may be included in the starting material within a range that does not interfere with the effects of the present invention. Here the explanation will be based on the starting materials for a typical unit for structuring the elastic polyurethane yarn according to the present invention. The diol polymer used in the present invention is preferably a polyether or polyester diol, a polycarbonate diol, or the like. Furthermore, from the perspective of imparting flexibility and elongation to the yarn, the use of a polyether diol is particularly preferred. The polyether diol may be, for example, polyethylene oxide, polyethylene glycol, a polyethylene glycol derivative, polypropylene glycol, polytetramethylene ether glycol (hereafter abbreviated as PTMG), modified PTMG (hereafter abbreviated as "3M-PTMG") which is a copolymer of tetrahydrofuran (THE) and methyltetrahydrofuran, modified PTMG which is a copolymer of THE and 2,3-dimethyl THE, a polyol having side chains on both sides, described, for example, in Japanese patent 2615131, a random copolymer with THE wherein ethylene oxides and / or propylene oxides are randomly arranged, or similar. These polyether diols may be of a single type or a mixture of two or more types, or may be used in a copolymerization. Furthermore, from the perspective of wear resistance and light stability of the polyurethane elastic yarn, a polyester diol is preferably used, such as butylene adipate, polycaprolactone diol, or a polyester polyol having side chains as described, for example, in the WUUa / 2U21 / Ul ^203 unexamined Japanese patent application publication S6126612, or similar, or a polycarbonate diol, as described, for example, in examined Japanese patent application publication H2-289516. Furthermore, these polymeric diols can be used alone, in a mixture of two or more of them, or used in copolymerization. Preferably, the molecular weight of the diol polymer used in the present invention, from the perspective of providing elongation, tensile strength, thermal durability, and the like, when transformed into a yarn, is a number-average molecular weight of not less than 1000 and not more than 8000 and, more preferably, not less than 1800 and not more than 6000. The use of a polyol of a molecular weight in this range facilitates the production of an elastic yarn that is superior in elongation, tensile strength, elastic recovery strength, and thermal durability. For the diisocyanate used in the present invention, aromatic diisocyanates such as diphenylmethane diisocyanate (hereafter abbreviated as MDI), tolylene diisocyanate, benzene 1,4-diisocyanate, xylylene diisocyanate, 2,6-naphthalene diisocyanate, and the like, are very suitable for synthesizing a polyurethane with high thermal durability and high strength. Furthermore, for an alicyclic diisocyanate, such as methylene bis(cyclohexyl)isocyanate, isophorone diisocyanate, methyl cyclohexane 2,4-diisocyanate, methyl cyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexahydroxylene diisocyanate, hexahydlylene diisocyanate, octahydro 1,5-naphthalene diisocyanate, and the like are preferred. Aliphatic diisocyanates can be used effectively, in particular, to suppress yellowing of polyurethane elastic yarn. It is worth noting that these diisocyanates can be used alone, or two or more types can be used together. For the chain-extending agent in the present invention, a low molecular weight diamine and / or a low molecular weight diol is preferably used. It is noteworthy that a hydroxyl group and an amino group may be included within the molecule, as in ethanolamine. Preferred low molecular weight diamines include, for example, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, pxylylenediamine, m-xylylenediamine, p,p'-methylenedianiline, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, bis(4-aminophenyl)phosphine oxide, and the like. Preferably, one or more of these are used. Ethylenediamine is particularly preferred. The use of ethylenediamine makes it possible to produce a yarn that is superior in terms of elongation and elastic recovery properties, as well as thermal durability. Triamine compounds, for example, diethylenetriamine and the like, capable of forming crosslinking structures, can be added to the chain-extending agent in an amount that does not interfere with its effects. In addition, ethylene glycol, 1,3-propanediol, 1,4-butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, 1-methyl-1,2-ethanediol, and similar compounds are typical low-molecular-weight diols. Preferably, one or more of these are used. In particular, ethylene glycol, 1,3-propanediol, and 1,4-butanediol are preferred. Their use allows for the production of a yarn with greater thermal durability and increased strength, similar to an elongated polyurethane. Furthermore, preferably the molecular weight of the polyurethane elastic yarn according to the present invention, from the perspective of producing a fiber with high durability and strength, is in the range of not less than 30,000 and not more than 150,000, as the number-average molecular weight. It should be noted that the molecular weight is measured using GPC and is an equivalent calculated using polystyrene. In the present invention, including in the basic structure of the polyurethane elastic yarn, as described above, a hydrocarbon resin (A) having a structure in which a polymer including, as a main structural unit, a structural unit in which an aromatic olefin and / or aliphatic diolefin is a monomer is partially or fully hydrogenated, can greatly improve the adhesion properties, when used as a hot melt, as well as improve the unwinding properties of the polyurethane elastic yarn. There are no particular limitations with respect to the hydrocarbon resin (A) in the present invention, provided that it has a structure in which a polymer, including as its principal structural unit a structural unit in which an aromatic olefin and / or aliphatic diolefin is the monomer, has been partially hydrogenated (sometimes referred to as "partial hydrogenation" hereinafter) and / or fully hydrogenated (sometimes referred to as "full hydrogenation" hereinafter). It is noteworthy that partial hydrogenation in the present invention refers to between 50% and 100% of the double bonds that are included in the normal polymer undergoing hydrogenation. Furthermore, when referred to simply as "hydrogenation," this indicates the ranges of partial and full hydrogenation.In this description, the “polymer comprising, as a principal structural unit, a structural unit in which an aromatic olefin and / or aliphatic diolefin is a monomer” will be referred to as a “hydrocarbon resin precursor polymer.” Generally, both the “hydrocarbon resin precursor polymer” and the “hydrocarbon resin (A)” are simply called “petroleum resins,” and often no distinction is made between them. However, in the present invention, they are distinguished by their structures, as described above. It is noteworthy that, of the “hydrocarbon resins (A),” the one that is fully hydrogenated may also be referred to as a “saturated hydrocarbon resin.”The hydrocarbon resin (A) can have structural units of multiple types, and a partially hydrogenated structure. In such cases, it would be difficult to accurately express the structure using a chemical name. Therefore, for the sake of convenience in the explanation below, the specification will be based on the monomer that forms the structure before hydrogenation. That is, the monomer is used to specify a structure derived from it and is not intended to limit the raw material. The petroleum resin that is the precursor polymer of the hydrocarbon resin and the hydrocarbon resin (A) can be a "C9 petroleum resin" that uses primarily an aromatic olefin as a monomer, a "C5 petroleum resin" that uses primarily an aliphatic diolefin as a monomer, or a "C5 / C9 petroleum resin" that is a mixture of both. In this case, the expression "uses primarily an aromatic olefin as a monomer" refers to structural units derived from aromatic olefins comprising more than 50 mol% of the total, including structural units derived from other monomers. Similarly, the expression "uses primarily an aliphatic diolefin as a monomer" refers to structural units derived from aliphatic diolefins comprising more than 50 mol% of the total, including structural units derived from other monomers. The monomer that provides the structural units of C9 petroleum resin (sometimes referred to as "C9 petroleum resin monomer" below) may have alkylbenzene and an aromatic olefin as major components, where the alkylbenzene may be isopropylbenzene, n-propylbenzene, l-methyl-2-ethylbenzene, 1-methyl-3-ethylbenzene, l-methyl-4-ethylbenzene, 1,3,5-trimethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, l-methyl-2-n-propylbenzene, l-methyl-3-ηpropylbenzene, l-methyl-4-isopropylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, or the like. Furthermore, the aromatic olefin may be α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, indene, m-methylpropenylbenzene, m-methylisopropenylbenzene, p-methylisopropenylbenzene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, m,m-dimethylstyrene, dimethylstyrene, methylindene, or the like. In the present invention, when the petroleum resin C9 is included in the hydrocarbon resin precursor polymer or the hydrocarbon resin (A), indene and methylstyrene are preferably included as monomers. The monomer providing the structural unit for the C5 petroleum resin (sometimes referred to as the "C5 petroleum resin monomer" hereafter) may be 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, cyclopentene, 1,3-pentadiene, isoprene, cyclopentadiene, dicyclopentadiene, or the like. When, in the present invention, the C5 petroleum resin is included in the hydrocarbon resin precursor polymer or hydrocarbon resin (A), isoprene is preferably included as the monomer. The inclusion of such a hydrocarbon resin (A) can improve the heat-bonding properties of the polyurethane elastic yarn in particular. The hydrogenated petroleum resin (C5 petroleum resin and / or C9 petroleum resin) has superior compatibility with component (a) of the present invention and can be stably incorporated into the polyurethane elastic yarn. Preferably, the softening point of the hydrocarbon resin (A) in the present invention is in the range of 70 to 140 °C, to ensure good adhesion to the hot melt adhesive and good compatibility with the hydrocarbon oil (b) during manufacturing, as described below. The use of a hydrocarbon resin (A) with a softening point of at least 70 °C not only further improves the ability to maintain bond strength with the hot melt adhesive in a high-temperature environment after the adhesive has hardened, but also results in good resistance to deformation.On the other hand, the use of a hydrocarbon (A) where the softening point is no greater than 140 °C causes the compatibility with the hydrocarbon oil (b) to be superior when manufactured as described below, which makes it possible to dissolve the hydrocarbon resin (A) in the hydrocarbon oil (b) at high concentrations, greatly reducing the amount by which the stretchability of the polyurethane elastic thread is reduced. It is worth noting that the "hydrocarbon resin softening point (A)" is the value measured according to JIS K 2207:2006. Of the products commercially available as petroleum resins for hydrocarbon resin (A), those commercially available as hydrogenated or saturated hydrocarbon resins may be used. For example, it could be one of the following products or similar ones: Partially hydrogenated petroleum hydrocarbon resins in which an aliphatic component and an aromatic component are copolymerized: Manufactured by Idemitsu Kosan: «I-Marv (registered trademark)» S-100 (softening point = 100 °C) «I-Marv (registered trademark)» S-110 (softening point = 110 °C) . Fully hydrogenated petroleum hydrocarbon resins in which an aliphatic component and an aromatic component are copolymerized: Manufactured by Idemitsu Kosan: "I-Marv (registered trademark)" P-100 (softening point = 100 °C) "I-Marv (registered trademark)" P-125 (softening point = 125 °C). Manufactured by Tonen General Sekiyu: "T-REZ (registered trademark)" HB103 (softening point = 100 °C) "T-REZ (registered trademark)" HB125 (softening point = 125 °C) Fully hydrogenated petroleum hydrocarbon resins of aliphatic petroleum hydrocarbon resins: Manufactured by Eastman Chemical Company: "Eastotac (registered trademark)" H-130W (softening point = 130 °C) Partially hydrogenated petroleum hydrocarbon resins of aromatic petroleum hydrocarbon resins: Manufactured by Arakawa Chemical Company: "ARKON (registered trademark)" M-100 (softening point = 100 °C) "ARKON (registered trademark)" M-135 (softening point = 135 °C) Fully hydrogenated petroleum hydrocarbon resins of aromatic petroleum hydrocarbon resins: Manufactured by Arakawa Chemical Company: "ARKON (registered trademark)" P-90 (softening point = 90 °C) "ARKON (registered trademark)" P-125 (softening point = 125 °C) These hydrocarbon resins (A) may be present uniformly within the polyurethane elastic yarn, or they may be present at a higher concentration in a specific region; however, from the perspective of improving the bonding properties by heat fusion, they preferably exist at higher concentrations near the surface layer of the polyurethane elastic yarn. Furthermore, the total inclusion ratio within the polyurethane elastic yarn is preferably between 0.1% and 10% by mass. For optimal stress relaxation, permanent strain rate, and elongation, a range of 1% to 5% by mass is preferred. A total inclusion ratio below 0.1% by mass could reduce the performance of the hot melt adhesive, which is undesirable. Conversely, a total inclusion ratio exceeding 10% by mass could negatively affect stress relaxation, permanent strain rate, and elongation, and is therefore undesirable. It is worth noting that, ideally, the inclusion ratios are tested beforehand and adjusted accordingly. Furthermore, in the present invention, the hydrocarbon resin (A) dissolves at not less than 10% by mass at 20°C with respect to the hydrocarbon oil (b) and is insoluble in DMAc and / or DMF. The hydrocarbon resin (A) having this solubility makes it possible to produce an elastic polyurethane yarn that has superior heat-bonding and unwinding properties. Preferably, the hydrocarbon resin (A) has a solubility of not less than 10% by mass at 20°C with respect to the hydrocarbon oil (b), as this makes the affinity with the hot melt adhesive agent better. On the other hand, while it is possible to produce a higher heat fusion adhesion performance by making the hydrocarbon resin (A) have a high solubility at 20 °C with respect to the hydrocarbon oil (b), if there were a solubility greater than 80%, then there could be an increase in the amount of yarn breakage, due to the evaporation of the elastic polyurethane yarn during spinning, which would be undesirable. Furthermore, the fact that the hydrocarbon resin (A) is insoluble in DMAc and / or DMF, which are solvents for polyurethane elastic solutions, allows for higher concentrations to be achieved near the surface layer of the polyurethane elastic yarn. In this case, "insoluble" refers to a solubility range of no more than 5% by mass when stirred for one hour at 20°C. The fact that the hydrocarbon resin (A) is tilted towards the proximity of the surface layer in the polyurethane elastic yarn allows for the demonstration of more superior heat-fusion adhesion properties, which would work to cause a reduction effect on the coefficient of friction between the polyurethane elastic yarns and may also improve the unwinding properties of the polyurethane elastic yarn. There are no particular limitations with respect to the hydrocarbon oil (b) in the present invention, provided that the proportion of hydrocarbon components having between 6 and 60 carbon atoms is not less than 90%, and the hydrocarbon oil (b) is fluid at 30°C, and its chemical structure may be linear or branched. Furthermore, it may contain hydroxyl groups in a portion, within a range that reduces hydrophobicity. Among these, mineral oils and higher alcohols are preferred for the hydrocarbon oil (b) due to their availability and cost. Although there are no particular limitations regarding mineral oil, machine oil, spindle oil, liquid paraffin, or similar substances may be used, of one type or a mixture of two or more types. The viscosity of mineral oil at 30°C, as measured by a Redwood viscometer, is preferably between 30 and 350 seconds, more preferably between 35 and 200 seconds, and even more preferably between 40 and 150 seconds. Because it produces little odor, liquid paraffin is preferred as a mineral oil. While there is no particular limitation regarding the higher alcohol, it can be a linear and / or branched monoalcohol and, by way of specific examples, it can be: a linear alcohol such as hexanol, heptanol, octanol, nonaol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, heptacosanol, octacosanol, nonacosanol, triacosanol and the like; a branched alkanol such as 2-ethylhexanol, 2-propylheptanol, 2-butyl octanol, 1-methylheptadecanol, 2-hexyloctanol, 1-hexylheptanol, isodecanol, isotridecanol, 3,5,5-trimethylhexanol and the like;a linear alkenol such as hexenol, heptenol, octenol, nonenol, decenol, dodecenol, tridecenol, tetradecenol, pentadecenol, hexadecenol, heptadecenol, octadecenol, nonadecenol, icosenol, dococenol, tetracosecol, pentacosenol, hexacosenol, heptacosenol, octacosenol, nonacoseneol and triaconsenol, and the like; a branched alkenol such as isohexenol, 2-ethylhexenol, isotridecenol, 1-methyl heptadecenol, 1-hexyl heptenol, isotridecenol, isooctadecenol and the like; etc.; Furthermore, the polyurethane elastic yarn according to the present invention preferably includes a hydrocarbon oil (b) in a range where the total inclusion proportion in the polyurethane elastic yarn is not less than 0.01% by mass nor greater than 20% by mass and, from the perspective of improving, in particular, stress relaxation, permanent strain rate and elongation, a range not less than 0.01% by mass and not greater than 10% by mass is even more preferred. Furthermore, in the polyurethane elastic yarn according to the present invention, a type of terminal blocking agent, or a mixture of two or more types of terminal blocking agents, is preferably used. Preferably, the terminal blocking agent is: a monoamine such as dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, diamylamine, or the like; a monool such as ethanol, propanol, butanol, isopropanol, allyl alcohol, cyclopentanol, or the like; a monoisocyanate such as phenyl isocyanate or the like; etc. Furthermore, the polyurethane elastic yarn according to the present invention may include various types of stabilizing agents, pigments, and the like. For example, preferably BHT or a hindered phenol-based chemical, such as "Sumilizer GA-80" manufactured by Sumitomo Chemical Industries Corporation; various types of benzotriazole or benzophenone-based chemicals, such as "Tinuvin" manufactured by Ciba Geigy Corporation; phosphorus-based chemicals, such as "Sumilizer P-16" manufactured by Sumitomo Chemical Industries Corporation; various types of hindered amine-based chemicals; various types of pigments, such as iron oxide, titanium oxide, and the like; inorganic substances such as zinc oxide, cerium oxide, magnesium oxide, calcium carbonate, carbon black, and the like; fluorine- or silicone-based resin powders; metallic soaps such as magnesium stearate and the like; and also germicides including silver.Zinc or zinc compounds, or similar deodorizing agents, various types of antistatic agents such as betaine, phosphoric acid-based agents, and similar substances are included in a light stabilizing agent and an oxide inhibitor and are preferably subjected to a polymer reaction. Additionally, and particularly to further improve resistance to light and various types of nitrogen oxides, a nitrogen oxide scavenger, such as HN-150, manufactured by Japan Hydrazine Corporation, a thermal oxidation stabilizing agent, such as "Sumilizer GA-80," manufactured by Sumitomo Chemical Industries Corporation, and an optical stabilizing agent, such as "Sumisorb 300#622," manufactured by Sumitomo Chemical Industries Corporation, are also preferably used. A method for manufacturing an elastic polyurethane yarn according to the present invention will now be explained in detail. In the present invention, a hydrocarbon resin (a) having a structure in which a polymer including, as main structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer, has been partially or fully hydrogenated, is dissolved in a hydrocarbon oil (b) and added to a spinning solution including a polyurethane (sometimes referred to as "polyurethane spinning solution" hereafter) in a range in which the hydrocarbon resin (a) is not less than 0.1% by mass and not more than 10% by mass with respect to the polyurethane solids content in the polyurethane spinning solution. The hydrocarbon oil (b) and the hydrocarbon resin (a) can be added together in the polyurethane polymerization step, but preferably the polyurethane solution is manufactured beforehand and the addition is made subsequently.In this case, the definition of hydrocarbon resin (a) is the same as for hydrocarbon resin (A) described above. This distinction in notation is made because hydrocarbon resin (a), as a manufacturing raw material, may include a plurality of components, where, for example, in a wet-spinning solution, there may be cases where the composition is not strictly identical to the hydrocarbon resin (A) in the resulting polyurethane elastic yarn, due to the distribution of components between solid / liquid and the spinning solvent. The method for manufacturing the polyurethane spinning solution, or the method for manufacturing the polyurethane that is the solute in the solution, can be either a melt polymerization method or a solution polymerization method. However, the solution polymerization method is preferred. With the solution polymerization method, there is little contamination, such as gel, produced in the polyurethane, and spinning is easy, facilitating the production of low-gauge elastic polyurethane yarn. Furthermore, by its very nature, solution polymerization has the advantage of allowing the step of converting the solution to a liquid to be omitted. Additionally, as a particularly ideal polyurethane in the present invention, the synthesis is carried out using PTMG with a molecular weight not less than 1500 and not greater than 6000 as the diol polymer, MDI as the diisocyanate, and 1,3 propanediol and / or 1,4 butanediol as the diol, with a melting point on the high-temperature side not less than 200 °C and not greater than 260 °C. Polyurethane can be obtained synthetically using the raw materials described above, in DMAc, DMF, DMSO, NMP, or similar solvents containing them as main ingredients. For example, it can be obtained using particularly suitable methods, such as a "one-step method," where the various raw materials are introduced into a solvent and dissolved, heated to a suitable temperature, and reacted to produce the polyurethane; or a method where the diol polymer and the diisocyanate are first melted and reacted, followed by WUUa / 2U21 / Ul ^203 of the reagent's dissolution in a solvent and reaction with the diol, described above, to produce a polyurethane or similar. When a diol is used with a chain-lengthening agent, the typical method for adjusting the melting point, on the high-temperature side, of the polyurethane to the range of not less than 200 °C and not more than 260 °C is achieved by controlling the types and proportions of the diol polymer, the MDI, and the diol. When the molecular weight of the diol polymer is low, a relatively large proportion of MDI allows the production of a polyurethane with a high melting point on the high-temperature side, and similarly, when the molecular weight of the diol is low, a relatively low proportion of the diol polymer makes it possible to produce a polyurethane with a high melting point on the high-temperature side. If the molecular weight of the diol polymer is 1800 or more, then, preferably, to make the melting point on the high-temperature side not less than 200 °C, the polymerization is carried out with a ratio of (moles of MDI) / (moles of diol polymer) = 1.5 or more. Please note that, when synthesizing this polyurethane, preferably use at least one catalyst, or a mixture of two or more catalysts, such as an amine catalyst or an organic metal catalyst, or similar. The amine catalyst can be, for example, N,N-dímetíleíclohexílamina, N,N-dimethylbencylamine, triethylamine, N-methylmorpholine, N ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, Ν,Ν,Ν',Ν'tetramethyl-1,3-propanodiamine, N, N, N',N'tetramethylhexanodiamine, bis-2-dimethylaminoethyl ether, Ν,Ν,Ν',N',N'-pentamethyldiethyleñotriamine, tetramethylguanidine, triethylenediamine, N,N'dimethylpiperazine, N-methyl-N'-dimethylaminoethylpiperazine, N(2-dimethylaminoethyl)morpholine, 1-methylimidazole, 1,2dimethylimidazol, N,N-dimethylaminoethanol, Ν,Ν,Ν'trimethylaminoethanolamine, N-methyl-N'-(2hidroxyethyl)piperazine, 2,4,6-tris(dimethylamino)methyl)phenol, N,N-dimethylamino hexanol, triethanolamine or similar. The organometal catalyst can be approximately tin octanoate, dibutyltin dilaurate, lead dibutyl octanoate, or similar. Preferably, the density of the polyurethane spinning solution produced in this way is typically in the range of not less than 30% by weight and not more than 80% by weight. In the present invention, preferably, the hydrocarbon resin (a), in which a polymer comprising, as main structural units, units using the aromatic olefin and / or aliphatic diolefin described above as monomers, is partially or fully hydrogenated, is added to the polyurethane solution before spinning. When the hydrocarbon resin (a), in which the structure comprising, as main structural units, units using aromatic olefin and / or aliphatic diolefin as monomers is partially or fully hydrogenated, is added to the polyurethane solution, and mixing or stirring is performed to disperse or dissolve it uniformly, any arbitrary method may be employed.Typical methods include various types of mixing techniques, such as those using a static mixer, agitation, a homomixer, or a twin-screw extruder. Here, the goal is to uniformly add to the polyurethane solution the hydrocarbon resin (a) having a structure where a polymer comprising structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer is partially or fully hydrogenated, first dissolved in the hydrocarbon oil (b) and then added. Furthermore, when the hydrocarbon resin (a) is added, which has a structure comprising a polymer that includes, as main structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer, and is partially or fully hydrogenated, chemical agents and pigments and the like, such as light-stabilizing agents, oxidation inhibitors, and the like, described above, can be added simultaneously. The elastic polyurethane yarn according to the present invention can be produced by, for example, dry spinning, wet spinning, or melt spinning of the spinning solution structured as described above, and then wound. Of these, dry spinning is preferred from the perspective of being able to reliably spin all gauges, from fine to coarse. There are no particular limitations regarding, for example, the gauge or cross-sectional shape of the polyurethane elastic yarn in the present invention. For example, the cross-sectional shape of the yarn can be circular or flat. Additionally, there is no particular limitation with respect to the dry spinning method, where spinning should be carried out after selecting the spinning conditions and the like, as appropriate according to the desired characteristics and spinning equipment. For example, because the rate of permanent deformation and tension relaxation of the polyurethane elastic yarn according to the present invention is particularly prone to be affected by the speed ratio between the godet roller and the winding equipment, this should be determined as appropriate depending on the intended use of the yarn. In other words, from the perspective of obtaining an elastic polyurethane yarn with a desirable permanent strain rate and stress relaxation, winding is performed with the speed ratio between the godet roll and the winding equipment in a range of not less than 1.10 and not greater than 1.65. Given this, when producing an elastic polyurethane yarn with a relatively low permanent strain rate and low stress relaxation, the speed ratio between the godet roll and the winding equipment is preferably in a range of not less than 1.15 and not more than 1.4, with a range of not less than 1.15 and not more than 1.35 being even more preferred.On the other hand, when producing a polyurethane elastic yarn that has a relatively high permanent deformation rate and high stress relaxation, preferably the winding is carried out with the speed ratio of the godet roll and the winding equipment in a range of not less than 1.25 and not more than 1.65, and more preferably in a range of not less than 1.35 and not more than 1.65. Furthermore, from the perspective of improving the strength of the produced polyurethane elastic yarn, preferably, the spinning speed is not less than 300 m / min. Furthermore, when winding the polyurethane elastic yarn, a treatment agent is preferably applied to improve its unwinding properties. When applying the treatment agent to the polyurethane elastic yarn, there is a method known as "pure oiling," where the oil is supplied as is, without diluting the treatment agent with a solvent or similar substance. The application stage can be at any point, such as after spinning and before winding into a bundle, during the forming stage on the forming machine, or similar stages. The application method can be a known method, such as roller oiling, guide oiling, spray oiling, or similar. The amount of treatment agent applied ranges from 0.1 to 7% by mass, with respect to the elastic polyurethane yarn, but, from the perspective of not interfering with the heat-fusion bonding properties, it is preferably between 0.1 and 3% by mass. The composition of the treatment agent can be a silicone-based oil, a mineral oil-based oil, or a mixed oil of silicone and mineral oil, as is generally used in polyurethane elastic yarns, but from the perspective of achieving both unwinding performance and heat-fusion adhesion performance, it is preferably a mineral oil-based oil or a mixed oil of a silicone mineral oil. Preferably, a silicone oil, or similar, is used, wherein the silicone is: 1) a polydimethylsiloxane prepared from dimethylsiloxane units; 2) a polydialkylsiloxane prepared from dimethylsiloxane units and dialkylsiloxane units including alkyl groups with carbon numbers between 2 and 4; 3) a polysiloxane prepared from dimethylsiloxane units and methylphenylsiloxane units; or similar. From the perspective of ease of handling and reduction of sliding friction against guide members and the like, a viscosity between 0.1 and 1000 mm² / s at 25 °C is preferred. This viscosity can be measured using the method described in JIS-K 2283 (Test methods for kinematic viscosity of crude oil and petroleum products and methods for calculating viscosity index). When using silicone oil, it is preferably mixed with a paraffin-based hydrocarbon, such as mineral oil, an antistatic agent, a dispersing agent, a metallic soap, and the like, for use. From the perspective of ease of handling and reduction of sliding friction against guide members and the like, paraffin-based hydrocarbon, such as mineral oil or the like, preferably has a viscosity of between 10 and 500 mm2 / s, at 25 °C. Preferably, an anionic surface activating agent such as an alkyl sulfate, fatty acid soap, alkyl sulfonate, alkyl phosphate ester or similar is used as an antistatic agent. Preferably, a silicone resin, a polyether-modified silicone, a carbonol-modified silicone, a carboxyl-modified silicone, an amino-modified silicone, an amide-modified silicone, a carboxyamide-modified silicone, a mercapto-modified silicone, an organic carboxylic acid, or similar materials, either individually or in a mixture thereof, are used as a dispersing agent. Magnesium stearate and calcium stearate are preferred for metallic soap, where, from the perspective of ease of handling and improved dispersion performance, the average particle diameter is preferably between 0.1 and 1.0 pm. Furthermore, as required, components used in standard synthetic fiber treatment agents, such as coupling agents, ultraviolet radiation-absorbing agents, oxidation inhibitors, corrosion inhibitors, wettability enhancers, and the like, are preferably included in the silicone oil used in the present invention. The inclusion proportions of the paraffin-based hydrocarbon, such as mineral oil or the like, metallic soap, anti-static agent, dispersing agent, etc., can be determined as appropriate for the purpose. EXAMPLES Although the present invention will be explained in more detail Using examples, the present invention is not limited to these forms. First, the methods for evaluating the various types of features in the present invention will be explained below. Tensile strength and elongation of polyurethane elastic yarn An Instron model 4502 tensile testing device was used to measure the strength and elongation at break of the polyurethane elastic yarn samples. Specifically, a sample yarn with a sample length of 5 cm (Ll) was stretched to 300% five times at a tensile speed of 50 cm / min. This length was then maintained for 30 seconds. On the sixth repetition, the sample yarn was stretched until it broke. The tensile strength at break was defined as (G3), and the sample length at break was defined as (L3). The characteristics described above are given by the following formulas: Breaking strength = (G3) Elongation at break = 100 x { (L3)- (Ll)} / (Ll) It should be noted that the traction test was performed five times and the average was calculated. Unwinding performance of polyurethane elastic yarn After storing a 4.5 kg coiled yarn body of the polyurethane elastic yarn for 14 days at an ambient temperature of 35 °C and 65% RH, the coiled yarn body was uncoiled to the position located 1 cm from the winding cone, and the coiled yarn body, after uncoiling, was placed so that its surface was in contact with a textured roller (a), and the polyurethane elastic yarn was extracted, at the surface speed of the roller of 30 m / min, while the roller was turned.The extracted polyurethane elastic yarn was rotated once around a textured roller (b) of the same diameter, positioned 100 cm away. The speed of the roller (b) surface was gradually varied to find the speed at which the polyurethane elastic yarn smoothly exited the roller (a) without lifting off the wound yarn body. The ratio of roller speeds (b) to (a) was defined as the unwinding performance of the polyurethane elastic yarn. Lower unwinding performance values ​​indicate better separation of the polyurethane elastic yarn. It should be noted that the unwinding performance test was performed using two bundles of wound yarn and the average of these was calculated. Adhesion performance by heat fusion A hot-melt adhesive agent, having as its main component a hydrogenated styrene-butadiene-styrene copolymer, melted in a container at 150 °C, in the proportions stipulated for individual polyurethane elastic threads (0.03 g / m, 0.07 g / m), was coated using a comb gun while eight lines of polyurethane elastic thread were moved in one direction with a uniform spacing between them, tensioned by a draw determined by a person (draw 3.0), onto a non-woven fabric made of polypropylene with a width of 15 cm, moving at a speed of 130 m / min, after which another non-woven fabric made of polypropylene was placed on top of this from above, bonded by contact and rolled up to produce a stretchable sheet. The stretchable sheet obtained in this manner was secured to a flat wooden board. With the nonwoven fabric fully stretched, a razor blade was used to cut 16 points from the top of the stretchable sheet, 30 cm from the end, at both ends of each of the eight polyurethane elastic yarns in the nonwoven fabric. This tension plate was stored at 40 °C, 80% RH. The shrinkage of the polyurethane elastic yarn, secured with the hot-melt adhesive to the polypropylene nonwoven fabric—specifically, the yarn length (L4) after sliding, as the original length, and the length (L5) between the two cut portions—was measured after two and eight hours of storage. It is worth noting that the measurements were performed for a total of 24 elastic fibers, and the average retention rates of the hot-melt bond were calculated for all 24 fibers. Adhesion maintenance rate by thermofusion (%) = 100 x (L4) / (L5) . Preparation of the solution (Al) A solution (Al) was prepared by dissolving 20% ​​by mass of a hydrocarbon resin manufactured by Arakawa Chemical Company (“ARKON (registered trademark)” P-90, thermal softening point = 90 °C) in mineral oil where the proportion of components having a carbon number of not less than 30 was 2%, for 100 seconds at 35 °C, using a Redwood viscometer. Preparation of the solution (A2) A solution (A2) was prepared by dissolving 40% by mass of a hydrocarbon resin manufactured by TXTE Energy (“T-REZ (registered trademark)” RA100, thermal softening point = 99 °C) in mineral oil where the proportion of components having a carbon number of not less than 30 was 1%, for 80 seconds at 35 °C, using a Redwood viscometer. Solution preparation (A3) A solution (A3) was prepared by dissolving 40% by mass of a hydrocarbon resin manufactured by JXTE Energy (“T-REZ (registered trademark)” RA1115, thermal softening point = 114 °C) in mineral oil where the proportion of components having a carbon number of not less than 30 was 1%, for 80 seconds at 35 °C, using a Redwood viscometer. Solution preparation (A4) A solution (A4) was prepared by dissolving 20% ​​by mass of a hydrocarbon resin manufactured by Arakawa Chemical Company ("ARKON (registered trademark)" M-135, thermal softening point = 135 °C) in mineral oil where the proportion of components having a carbon number of not less than 30 was 2%, for 100 seconds at 35 °C, using a Redwood viscometer. Table 1 IVIA / a / ZUZ I / υΊ 4ZO3 Hydrocarbon resin (a) Hydrocarbon oil (b) Softening point: 90 °C Softening point: 99 °C Softening point: 115 °C Softening point: 135 °C Viscosity: 100 at 35 °C Viscosity: 80 at 35 °C Arkon (R) P-90 T-REZ RA 100 T-REZ RC 115 Arkon (R) M-135 Solution (A1) 40 60 Solution (A2) 40 60 Solution (A3) 40 60 Solution (A4) 20 80 Example 1 MDI and PTMG, with a number average molecular weight of 1800, were loaded into a container so that the molar ratio was MDI / PTMG = 1.58 / 1. They were reacted at 90 °C, and the resulting reaction product was dissolved in N,N-dimethylacetamide (DMAc). A DMAc solution containing ethylenediamine and diethylamine was then added to the solution containing the aforementioned reaction product to prepare a urea polyurethane solution with a polymer solids content of 35% by mass. Following this, a condensation polymer of p-cresol and divinylbenzene ("Metachlor (registered trademark)" 2390, manufactured by DuPont Corporation), as an oxidation inhibitor, and 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5triazine-2-yl]-5-(octyloxy)phenol ("Cyasorb (registered trademark)" 1164, manufactured by Cytec Corporation), as an ultraviolet radiation absorbing agent, were mixed in a mass ratio of 3:2, to prepare the DMAc solution (concentration: 35% by mass), and this was used as the additive solution (35% by mass). The polyurethane urea solution and the additive solution were mixed in a ratio of 98% by mass:2% by mass to produce the polyurethane spinning solution (XI). The solution (Al) was mixed to be 10% by mass relative to the solids content of the polyurethane spinning solution (XI) to prepare a spinning solution (Yl). An elastic polyurethane yarn (580 decitex, 56 filaments) (Zl) was manufactured by dry spinning this spinning solution (Yl) at a winding speed of 500 m / min to produce a wound yarn body of 4.5 kg. Example 2 As a treatment agent when winding the elastic polyurethane yarn, a treatment agent (Bl) of 25% polydimethylsiloxane, 73% mineral oil and 2% St-Mg was prepared. A 4.5 kg body of wound yarn was produced in the same way as in Example 1, in addition to winding while applying the treatment agent (Bl), at 1% dry mass, to the elastic polyurethane yarn during winding. Examples 3-6, Reference Examples 1-4 4.5 kg wound yarn bodies were produced from polyurethane elastic yarns in the same way as in Example 1 or Example 2, with the exception of the variation in the types and / or proportions of inclusion of the components as shown in Table 1. Examples 7-8 and Reference Examples 5-6 4.5 kg coiled yarn bodies were produced from elastic polyethylene yarns in a similar manner WUUa / 2U21 / Ul ^203 ML / a / ZUZ I to the other examples and reference examples, except for the change of gauge to 310 decitex (32 filaments) as shown in Table 1. The results of the various evaluations of the produced yarns are shown in Table 1. The polyurethane elastic yarns from Examples 1 to 8 demonstrated adequate performance in all evaluations. On the other hand, in Reference Examples 1-6, the results were unsatisfactory in both unwinding performance and heat fusion bonding performance. Reference example 7 Solution preparation (A5) Although an attempt was made to dissolve 20% by mass of a hydrocarbon resin, manufactured by Arakawa Chemical Company ("ARKON (registered trademark)" P-90, thermal softening point: 135 °C) in mineral oil where the proportion of components with a carbon number of not less than 30 was 38%, for 250 seconds at 35 °C using a Redwood viscometer, complete dissolution was not possible and therefore this could not be added to the polyurethane solution. Table 2 Polyurethane elastic yarn Hydrocarbon resin solution Hydrocarbon resin (A) Bond retention rate by heat fusion Release capacity Elongation at fracture Tensile strength (dtex) Treatment agent (B1) Type Softening point (°C) Amount added (%) After 2 hours After 8 hours () (%) (cN) Mode 1 580 None (A1) Arkon P-90 90 5 92 87 2.0 521 340 Mode 2 580 1 % (A1) Arkon P-90 90 5 93 88 1.7 525 342 Mode 3 580 None (A2) T-REZ RA100 99 8 93 87 2.2 501 322 Mode 4 580 1 % (A2) T-REZ RA100 99 8 94 89 1.6 509 328 Mode 5 580 None (A3) T-REZ RC115 115 0.8 92 84 2.1 533 349 Mode 6 580 1 % (A3) T-REZ RC115 115 0.8 92 83 1.9 530 344 Mode 7 310 None (A4) Arkon M-135 135 2 97 93 2.2 508 190 Mode 8 310 1 % (A4) Arkon M-135 135 2 98 93 1.9 513 194 Reference Example 1 580 None Not Used 0 84 61 2.8 522 335 Reference Example 2 580 1 % Not used 0 80 55 2.3 528 341 Reference example 3 580 None Not used 0 83 60 2.7 511 339 Reference example 4 580 1 % Not used 0 82 51 2.3 506 333 Reference example 5 310 None Not used 0 97 90 3.0 511 192 Reference example 6 310 1 % Not used 0 94 87 2.5 497 188. Industrial applicability The polyurethane elastic thread according to the present invention has superior adhesion properties compared to the hot-melt adhesive and can be used appropriately in hygiene products such as disposable diapers, sanitary napkins, and the like, providing superior comfort and fit. Furthermore, it exhibits superior productivity, with no broken threads in the manufacture of hygiene products such as disposable diapers, sanitary napkins, and the like, even at high speeds, due to its superior unwinding properties. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. An elastic polyurethane yarn, characterized in that it includes: a hydrocarbon resin (A) having a structure in which a polymer including, as main structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer, is partially or fully hydrogenated; and a polyurethane.

2. An elastic polyurethane yarn according to claim 1, characterized in that: the hydrocarbon resin (A) has a structure in which the polymer including structural units using an aromatic olefin as a monomer is partially or fully hydrogenated, and the aromatic olefin is indene and / or methylstyrene.

3. An elastic polyurethane yarn according to claim 1 or 2, characterized in that: the hydrocarbon resin (A) has a structure in which the polymer, which includes structural units using an aliphatic diolefin as a monomer, is partially or fully hydrogenated, and the aliphatic diolefin is isoprene and / or an isomer thereof.

4. An elastic polyurethane yarn according to any of claims 1 to 3, characterized in that: the thermal softening point of the hydrocarbon resin (A) is not less than 70 °C nor greater than 140 °C.

5. An elastic polyurethane yarn according to any of claims 1 to 4, characterized in that: the hydrocarbon resin (A) is included in not less than 0.1% by mass and not more than 10% by mass.

6. An elastic polyurethane yarn according to any of claims 1 to 5, characterized in that: the hydrocarbon resin (A) dissolves at not less than 10% by mass at 20°C with respect to a hydrocarbon oil (b) and is insoluble in DMAc and / or DMF.

7. A method for manufacturing an elastic polyurethane yarn, characterized in that: after a hydrocarbon resin (a) having a structure in which a polymer including, as main structural units, structural units using an aromatic olefin and / or an aliphatic diolefin as a monomer is partially or fully hydrogenated is dissolved in a hydrocarbon oil (b), the hydrocarbon resin (a) is added so as to be in the range of not less than 0.1% by mass and not more than 10% by mass with respect to a solid polyurethane content in a polyurethane spinning solution, and is spun in solution.

8. A method for manufacturing an elastic polyurethane yarn according to claim 7, characterized in that: after the hydrocarbon resin (a) is dissolved to a concentration of not less than 5% in the hydrocarbon oil (b), it is added to a polyurethane spinning solution, and spun in solution.