KR100200425B1 - The polyurethane system elastic fiber manufacture method - Google Patents

Abstract

The present invention relates to a method for producing a polyurethane elastic fiber used in stockings, women's underwear and sports clothing with excellent physical properties such as elasticity, elastic recovery, etc., and particularly to improve the heat resistance, maritime resistance and spinning speed. .

In the present invention, a long-chain diol in which a polyether diol and a polycarbonate-based diol are mixed, a polyol having 2-7 amino groups and 3-12 carbon atoms is prepolymerized with an excess of an organic diisocyanate compound to be mixed with a solvent at a constant ratio. Regarding a method for producing a polyurethane elastic fiber, characterized in that the polymer produced by using the post-chain growth agent and the chain stopper is prepared using a polymer added with the heat resistance improving additive and the nautical resistance improving additive used in the present invention. In this case, the use of such a manufacturing method can significantly reduce the amount of solvent input compared to the conventional elastic fibers, so that excessive heat for solvent evaporation is not used. Not only can it improve the heat resistance, but also improve the heat resistance and maritime resistance. A.

Description

Polyurethane Elastic Fiber Manufacturing Method

The present invention relates to a method for producing a polyurethane-based elastic fiber excellent in the maritime properties and heat resistance while maintaining the inherent physical properties of the polyurethane elastic fiber.

Polyurethane-based elastic fibers have been widely used in stockings, women's underwear and stretch fabrics because of their excellent elasticity and elastic recovery ability, and their use as swimwear continues to expand. Such polyurethane-based elastic fibers are poor in heat resistance, and when mixed with other materials such as polyester fibers, high temperature dyeing of about 130 ° C. is impossible, and thus dyeing is difficult.

In addition, spandex filaments are slightly tacky when compared to other fabric filaments, so that the filaments are tacky to each other or to different surfaces, especially when wound on bobbins and re-released into different packages. When the coastal force is high in this way, problems such as trimming and shape irregularities due to tension unevenness are likely to occur in the covering process with nylon or the like or subsequent manufacturing process of the circular knitted fabric.

As a conventional technique for improving maritime properties, for example, USP 3039885 proposes a metal salt soap dispersed in an emulsion, wherein the metal in the metal salt soap is lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, Barum, zinc, cadmium, aluminum, etc., fatty acids are characterized by consisting of 8 to 22 carbon atoms.

In addition, USP 3296063 proposes a method of improving dissolvability by mixing and dispersing magnesium stearic acid, zinc stearic acid, and the like in an emulsion solution to impart an emulsion consisting of polyamylsiloxane / polydimethylsiloxane to spandex filaments.

In addition, Japanese Patent Application Laid-Open No. 59-26573 describes the addition of a metal compound of thiohedoxy acid to a polymer in any step prior to spinning to enhance running and maritime properties during spinning, and in Japanese Patent Laid-Open No. 60-239519 This month, silica is contained in an emulsion, and a method of enhancing the maritime properties and running friction characteristics is described by using metal soap salts together. In addition, Japanese Patent Application Laid-Open No. 56-107010 used a fatty acid metal salt, and Japanese Patent Application Laid-open No. 5-5277 proposed a method for enhancing maritime properties by using polyorganosiloxane as an emulsion for elastic fibers.

On the other hand, conventional techniques for improving the heat resistance include a separate heat resistance improving additive, for example, triazole-based, hindered phenol-based, semicarbazide end groups, or the like, or a portion of the high molecular weight diol compound diol Substituting the compound, the low molecular weight diol compound may be ethylene glycol, diethylene glycol, propylene glycol, 1, 4, -butane diol and the like. In Japanese Patent Publication Hei 4-74457, polytetramethylene glycol is reacted with an excess of 4,4'-diphenylmethane diisocyanate, followed by spinning the polymer chain-grown with 1, 2-propylene diamine and diethylene amine. A method for improving the elastic recovery rate by heating an elastic yarn at a constant temperature has been proposed, and in European Patents 343572 (A2), European Patents 358555 (A2) and European Patents 409735 (A1), polycarbonate diol compounds or polycaprolactone diols are proposed. A method of spinning using a polymer obtained by chain growth in a general manner using a compound is presented. In addition, a method of improving heat resistance using denatured amines has been proposed, but in most cases, the degree of improvement in heat resistance has not been satisfactorily achieved according to an independent prescription.

Known as a method for enhancing the elastic recovery rate is a method of heat treatment after the spinning process mentioned above, a method of chain growth using a tertiary nitrogen amine compound, diol and / or diamine compound having a divalent or higher end group prepolymer The method of introducing into the polymer forming step of the forming step or chain growth process. However, in such a method, there is a problem in that a phenomenon such as deterioration of elastic properties is caused by excessive crosslink formation rather than improvement of elastic recovery rate.

The present invention has a long chain diol (A) obtained by mixing a polyether diol (A-1) and a polyester diol (A-2) with 2 to 7 amino groups and 3 to 12 carbon atoms having at least one tertiary amino group. Polyols (B) are prepolymerized with an excess of diisocyanate (C) to mix a solvent and a fixed ratio, and then the terminal isocyanate is chain-grown using an appropriate amount of a diamine compound (D) to obtain a suitable viscosity for spinning. By blocking the end with an amine compound (E) and adding the seaweed enhancement additive (F) and the heat resistance additive (G), the elastic recovery ability as well as the polyester diol and the heat resistance improvement, while maintaining the inherent physical properties of the elastic fiber The synergistic effect of additives significantly improves the heat resistance and improves the disintegration properties. To have its purpose.

The present invention provides a long-chain diol (A) and a tertiary amino group obtained by mixing a polyether diol (A-1) having a number average molecular weight of 1,000 to 3,000 with an aliphatic polyester diol (A-2) having a number average molecular weight of 500 to 5,000. The polyamine (B) having 2 to 7 amino groups and 3 to 12 carbon atoms having at least one is prepolymerized with an excess of an organic diisocyanate compound (C), mixed with a solvent at a constant ratio, and then a diamine compound (D) as a chain growth agent. 0.5 to 0.98 moles of the prepolymer was added, and monoamine (E) as a chain stopper was added to 1 to 30 mole% of the total amine used to complete the polymerization, and then 0.01 to 1% by weight of the heat resistance improvement additive was added to the polymer solution. And a polymer prepared by adding an aliphatic metal salt compound for improving maritime property to 0.01 to 1% by weight based on the polymer solid content.

Hereinafter, the present invention will be described in detail.

In the present invention, as a long-chain diol (A) component that acts as a soft segment, a polyether diol (A-1) and a polyester-based diol (A-2) having excellent elastic recovery and heat resistance (A-2 / A-1) Is mixed so as to be 0.2 to 5 (more preferably 0.5 to 3), and the molar ratio (A / B) of the polyol (B) having a tertiary amino group to the long chain diol (A) is 5 to 50 (more preferably 12 to 35), and then prepolymerized with 1.23 to 2.7 moles of 4,4'-diphenylmethane diisocyanate, and mixed with an appropriate amount of dimethyl acetamide to prepare a prepolymer solution. Chain growth of terminal isocyanate using -0.98 moles to obtain 500-4,000 poises suitable for spinning, followed by chain stop monoamine compounds using 1-30 mole% of the total amine used, followed by chain stabilizers To maintain the proper viscosity for spinning In addition, to the polymer solution, an aliphatic metal salt compound for improving dissolvability is added in an amount of 0.01 to 1 weight based on polymer solid content, and 0.01 to 1 wt% of a heat resistance improving additive is added to the synergy effect with the polyester diol introduced in the prepolymer formation step. To significantly improve heat resistance.

As the polyether diol (A-1), polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or the like can be used, and a molecular weight of 1000 to 3000 (more preferably 1500 to 2500) is suitable. Suitable polyester diols (A-2) are polyester diols having a molecular weight of 500-5,000 prepared by aliphatic dibasic acids and low molecular weight glycols, and when the molecular weight exceeds 5,000, the durability is sharply lowered. If it is less than 500, rather than improving the heat resistance, it will cause a decrease in the elastic recovery force of the final spun yarn.

As the aliphatic dibasic acid in the composition of the polyester diol, an aliphatic dibasic acid having 3 to 14 carbon atoms or mixtures thereof including succinic acid, adipic acid, glutaric acid, maleic acid, pimeric acid, azeaic acid, sebacic acid, and the like are used. Low molecular weight glycols include glycols having 2 to 10 carbon atoms, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butane Diol, 2, 3-butane diol, 1, 5-pentane diol, 1, 6-hexane diol, 1, 4-cyclohexane diol, 1, 4-cyclohexane dimethanol, 2, 2-dimethyl-1, 3- Glycols, such as propane diol and 1, 8-octane diol, can be used individually or in mixture.

As the long-chain diol component of the polyurethane resin used in the present invention, the molar ratio of the polyester diol and the polyether diol is (A-2 / A-1) of 0.2 to 5 (more preferably 0.5 to 3), and poly If the proportion of ester diol is more than 5, the durability of the final polymer is lowered, and if it is less than 0.2, synergistic effect on the intended heat resistance improvement cannot be expected.

In addition, the polyurethane elastic fiber is made of a tertiary type of side chain in a position other than both ends using 2 to 7 amino groups and 3 to 12 carbon atoms (B) having at least one or more tertiary amino groups. By introducing an amino group, it has a network structure by urea bonds with isocyanates to form a strong bond, thereby improving heat resistance and elastic recovery ability and improving the viscosity stability of the polymer to maintain a suitable viscosity for spinning. .

As the polyol (B) component having a tertiary amino group, primary amines represented by R-NH ₂ (R: C _n H _{2n + 1} , n = 1 to 30) are ethylene oxide, propylene oxide, butylene oxide, and the like. The diols and derivatives thereof made by adding 2 to 55 moles of can be used. For example, N-methyl diethanolamine and N-ethyl diethanolamine obtained by adding 2 moles of ethylene oxide to primary amines such as methylamine, ethylamine, isopropylamine, n-butylamine and isobutylamine. Ethylene to alkylamines such as polyoxyethylene oleylamine in which 20 to 55 moles of ethylene oxide is added to N-alkyl diethanolamine such as N-isopropyl diethanolamine and laurylamine, stearylamine, and oleylamine. Diols to which an oxide, propylene oxide, and the like are added may be used.

The molar ratio between the long chain diol (A) and the polyol (B) having a tertiary amino group is A / B = 5 to 50

(Better than 12-35) is suitable, less than 5 is not dissolved in the solvent, it is a problem for spinning, and if it exceeds 50, the improvement of heat resistance and elastic recovery power is insignificant.

Examples of the diisocyanate compound (C) which combines with the amine compound which is a chain growth agent and acts as a hard segment include paraphenyl diisocyanate, metaphenylene diisocyanate, 2,4-torylene diisocyanate, 2 and 6-tori Ethylene diisocyanate, 1-chlor-2, 1-phenylene diisocyanate, 1, 5-naphthalene diisocyanate, 1, 4-phenylene diisocyanate, chlorphenylene-2, 4'-diisocyanate, methylenebis-4 -Phenyl diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl diisocyanate, methylcyclo hexylene diisocyanate, paraphenyl diisocyanate, paraphenylene diisocyanate, 4, 4'-diphenyl isopropylidine diisocyanate, 3, 3'-dimethyl-4, 4'-diphenyl diisocyanate, 3, 3'-dimethoxy-4, 4'-diphenylene diisocyanate, 4, 4'-diphenylmethane di There are compounds such as isocyanates, and 4,4'-diphenylmethane diisocyanate compounds are most preferred in consideration of reactivity with the diol compound and physical properties of the elastomer.

The amount of the diisocyanate compound (C) is suitably C / (A + B) = 1.23 to 2.7 moles with respect to the compound (A + B) mixed with the long-chain diol (A) and the polyol (B) having a tertiary amino group, but less than 1.23 moles. Essence of the polymer is excellent, but the strength is reduced and the elastic recovery power is insufficient, and when used more than 2,7 mol, the strength and elastic recovery rate is excellent, but the elongation is poor, resulting in the intrinsic physical properties of the elastomer.

The prepolymer obtained by combining the long-chain diol (A), the polyol (B), and the diisocyanate compound (C) is chain-grown by the diamine compound, chain-grown at a constant molecular weight, and chain-stopped with monoamine to obtain a polymer having a suitable molecular weight. Can be.

As diamine compound (D) which chain-grows a prepolymer, it is methyl iminobispropyl amine, 2, 5- dimethyl piperazine, 1, 2-propylene diamine, 2, 3- butylene diamine, meta styrene diamine, para styrene diamine. , 2-methyl piperazine, ethylene diamine, ethanol diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, 1-methyl-2, 4-diamine benzene, 1, 2-cyclohexane diamine, 1, 3-cyclohexane Compounds such as diamine, 1,4-cyclohexane diamine, octamethylene diamine, paraphenylene diamine and the like are used, and the range of use thereof is 0.5 to 0.98 moles with respect to the prepolymer, and beyond this range is required in the present invention. No properties are obtained.

In order to improve the viscosity stability of the polymer in the chain growth compound and the properties of the elastic yarn after spinning, it is preferable to use a mixture of linear amines and cyclic amines in an appropriate ratio. In this case, linear diamines (D-1) and cyclic When the molar ratio of (D-1) / (D-2) is 2-18, the molar ratio of diamine (D-2) is appropriate, and the molar ratio of (D-1) / (D-2) is less than 2. Since low molecular weight polymer is produced, mechanical properties such as strength, elongation, and elastic recovery rate are lowered. When the molar ratio of (D-1) / (D-2) exceeds 18, the reaction rate is too fast. Due to the large amount of reactants, the stability of the polymer is lowered and the heat resistance is also lowered.

Examples of the monoamine-based compound (E) which is a chain stopper for blocking the ends of the chain-grown prepolymer are monoethanol amine, diethanol amine, propyl amine, isopropyl amine, diisopropyl amine, 2-ethylhexyl amine, and di (2). -Ethylhexyl) amine, butyl amine and the like, but isopropyl amine is more advantageous when considering the reactivity with the chain growth diamine compound. The amount of the monoamine compound (E) is suitably 1 to 30% (mol%) of the total amine, and at less than 1%, the chain stopping effect is poor, so that the viscosity of the polymer rapidly rises and the viscosity changes with time. It continues to rise, making it unsuitable for spinning, and if it exceeds 30%, it does not prevent the chain growth of the polymer and grows into a polymer of proper molecular weight, so that it is not possible to obtain a viscosity suitable for spinning, and the physical properties, strength, elongation and elastic recovery rate of the polymer It becomes bad.

As a solvent for improving the radioactivity by controlling the solid content of the polymer, dimethylacetamide, dimethylformamide, hexamethylphosphoramide, dimethylnitrosoamine, dimethyl propionamide, methoxydimethylacetamide, N-methylpyrrolidine, dimethyl sulfoxide There are compounds such as seeds, tetramethylene sulfone and the like, and dimethylacetamide or dimethylformamide is more advantageous when considering compatibility with the polymer, radioactivity and solvent recoverability. The amount of the solvent to be used is preferably adjusted to 15 to 43% by weight of the solid content of the polymer, and less than 15% by weight or 43% by weight adversely affects radioactivity.

In the present invention, a phosphorus compound having an amine bond represented by the following Chemical Formula 1 is used to induce a synergy effect on improving heat resistance.

[Formula 1]

(Wherein R ¹ , R ² , R ³ , and R ⁴ are hydrogen atoms or alkyl groups or aryl groups having 1 to 10 carbon atoms, and R ⁵ is an alkylene group or benzene ring having 1 to 10 carbon atoms)

Phosphorus compounds having an amine bond include phosphoryldimethylethanolamine, 2-dimethylaminophenoldiphenyl phosphate, 2-diethylaminoethanoldimethyl phosphate, 2-ethylpropylaminophenoldihydrogen phosphate, and 2-dibutylaminophenol dihydro Gen phosphate and the like can be used.

The amount of phosphorus compound having an amine bond is preferably 0.01 to 1.0% by weight (more preferably 0.05 to 0.5% by weight) with respect to the solid content of the final polymer, and when it is less than 0.01% by weight, the effect of improving heat resistance is insignificant. The addition of excess stabilizer can cause deterioration of the polymer properties during spinning.

The fatty acid metal salts used in the present invention are fatty acid metal salt compounds in which the metal components are calcium, magnesium and lithium, and the fatty acids are saturated and / or unsaturated fatty acids having 10 to 22 carbon atoms, among which magnesium stearate shows excellent performance. The fatty acid metal salt may be used by spinning with other additives in the polymer solution, and by using the emulsion together with the oil during the finishing process of the spinning yarn.

The fatty acid metal salt used in the present invention is adjusted to have a solid concentration of 10 to 30% by weight in a dimethylacetamide solution and then milled to have a particle diameter of 0.1 to 1.0 micrometer or less. This is the case where particles of 1.0 micrometer or more are 0.1% or less of the total particles and particles of 0.3 micrometer or less are 95% or more of the total particles. In the case where an excessive amount of particles having a particle size exceeding 1 micrometer is included, problems such as trimming and combustion gas generation during spinning may occur.

The amount used when the polymer solution is added together with other additives is preferably adjusted to 0.01 to 1% by weight (more preferably, 0.1 to 0.6% by weight) based on the solids content of the polymer solution.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Tensile strength, elongation and elastic recovery rate shown in the examples were measured according to KSK 0219. Heat resistance was evaluated by strength retention and color change (Grat scale; ISO international standard) after 60 minutes treatment at 130 ℃ hot air dryer. Tension is defined as the dead force required to dissolve the yarn at a speed of 12 meters per minute from the bobbin, measured using a tension meter attached to the roller.

Example 1

1 mole of molecular weight 1,500 aliphatic polyester diols synthesized from 1,12-dodecaneioic acid and 2, 3-dimethyl-1, 2-propane diol, 1 mole of polytetramethylene glycol having a molecular weight of 1,800, N-isopropyl diethanol 0.1 mole of amine was stirred at 82 ° C. under reduced pressure to remove moisture, and 4.2 mole of 4,4′-diphenylmethane diisocyanate, which was preheated at 50 ° C., was added thereto, followed by polymerization at 80 ° C. × 60 min in a nitrogen gas atmosphere to prepare a prepolymer. Prepared. The prepolymer was dissolved in dimethyl acetamide, the solution was cooled to 5 ° C., and then 1 mol of ethylene diamine, linear amine, 0.8 mol of 1, 2-propylene diamine, and 0.2 mol of meta- styrene diamine as cyclic amine were used as chain growth agents. A chain growth agent solution in which 0.1 mol of 1,4-cyclohexane diamine was dissolved in dimethyl acetamide at a concentration of 15% was slowly added to the prepolymer to obtain a polymer having a viscosity of 2,950 poise, and 0.2 mol of isopropyl amine was added to the polymer. A solution dissolved at 15% concentration in dimethyl acetamide was slowly added to obtain a polymer having a viscosity of 3,000 poises.

After completion of the polymerization, a dissolution solution of phosphoryldimethylethanol amine, a heat resistance enhancing additive, was dissolved in dimethylacetamide at a concentration of 10%, so that the heat resistant additive was 0.2% by weight of the final polymer solids, and at the same time, magnesium stearic acid selected as a dissolution enhancing additive. Was mixed with dimethylacetamide at a concentration of 20% and milled so that particles having a particle diameter of 1 micrometer or more were 0.1% or less and particles of 0.3 micrometer or less were 95% or more of all particles using a conventional ball mill. The solution was added so that the magnesium stearic acid compound was 0.5% by weight of the final polymer solids, and the solid content of the final polymer was adjusted to 30% by weight.

The viscosity at this time is 2,600 poise (45 degreeC). This polymer was prepared by spinning a normal spinning method to prepare a polyurethane elastic yarn of 40 denier after spinning, the results of the evaluation of physical properties are shown in Table 1.

Comparative Example 1

The same procedure as in Example 1 was carried out except that N-isopropyl diethanolamine having a tertiary amino group was not used and phosphoryldimethylethanol amine, a heat resistance improving additive, was not used. Same as 1.

Comparative Example 2

Except for not using a phosphoryl dimethyl ethanol amine as a heat resistance improvement additive was carried out in the same manner as in Example 1, the results of evaluating the physical properties are shown in Table 1.

Comparative Example 3

2 moles of polytetramethylene glycol having a molecular weight of 1,800 and 0.1 moles of N-isopropyl diethanolamine were removed at 82 DEG C under reduced pressure without using an aliphatic polyester diol to remove moisture, and then preheated to 4, 4'- at 50 DEG C. 4. After adding 2 mol of diphenylmethane diisocyanate and polymerizing in a nitrogen gas atmosphere at 80 DEG C for 60 minutes to prepare a prepolymer, the polymerization was carried out in the same manner as in Example 1. However, the viscosity of the polymer after chain growth was 3,200 poise. The viscosity of the final polymer having a solid content of 30% added with an additive was 2,900 poises (45 ° C). The evaluation results of the physical properties are shown in Table 1.

Comparative Example 4

Except not using a magnesium stearic acid compound as a nautical enhancer was carried out in the same manner as in Example 1, the results of evaluating the physical properties are shown in Table 1.

Comparative Example 5

Except that the phosphoryl dimethyl ethanol amine as a heat resistance improving additive and the magnesium stearic acid compound as a dissolution resistance improving additive was used in the same manner as in Example 1, the physical properties are shown in Table 1.

Comparative Example 6

Without using aliphatic polyester diols, N-isopropyl diethanolamine and heat resistance enhancing additives, 4.1 moles of polytetramethylene glycol having a molecular weight of 1,800 was stirred at 82 ° C under reduced pressure to remove moisture, and then preheated to 4, 4 at 50 ° C. After the prepolymer was prepared by adding 4.2 moles of '-diphenylmethane diisocyanate to polymerization at 80 ° C. × 60 minutes in a nitrogen gas atmosphere, the polymerization reaction was carried out in the same manner as in Example 1. However, the viscosity of the polymer after chain growth was 3,000 poise. The viscosity of the final polymer having a solid content of 30% was 2,700 poises (45 ° C). The evaluation results of the physical properties are shown in Table 1.

Comparative Example 7

Except for not using aliphatic polyester diol, N-isopropyl diethanolamine, phosphoryldimethylethanolamine as a heat resistance improving additive, and magnesium stearic acid compound as a dissolution enhancing additive, it carried out similarly to Example 1, and evaluated physical properties. The results are shown in Table 1.

TABLE 1

* In heat resistance, class 5 is the best in class 5 and class 1 is the worst.

As can be seen from the above examples and comparative examples, the polyurethane fibers prepared according to the present invention have improved properties of heat resistance and disintegration of elastic fibers while maintaining inherent physical properties as fibers, as well as the amount of solvent added compared to the existing elastic fibers. Since it is possible to significantly reduce the amount of excess heat for solvent evaporation, the damage to the surface of the fiber is reduced and the spinning property is improved, thereby obtaining the usefulness to increase productivity.

Claims (7)

At least one long-chain diol (A) and a tertiary amino group obtained by mixing a polyether diol (A-1) having a number average molecular weight of 1,000 to 3,000 with an aliphatic polyester diol (A-2) having a number average molecular weight of 500 to 5,000 The polyol (B) having 2 to 7 amino groups and 3 to 12 carbon atoms (B) is prepolymerized with an excess of an organic diisocyanate compound (C), mixed with a solvent at a constant ratio, and then a prepolymer of a diamine compound (D) as a chain growth agent. 0.5 to 0.98 moles of monoamine (E), which is a chain stopper, was added to 1 to 30 mole% of the total amine used to complete polymerization, and then 0.01 to 1 weight of the heat resistance improving additive represented by the following formula (1) to the polymer solution. A method for producing a polyurethane-based elastic fiber, characterized in that the polymer is added using 0.01 to 1% by weight of an aliphatic metal salt compound added to the polymer solids to improve the dissolvability. [Formula 1]

(Wherein R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or alkyl groups or aryl groups having 1 to 10 carbon atoms, and R ⁵ is an alkylene group or benzene ring having 1 to 10 carbon atoms) The method of claim 1, wherein the long-chain diol (A) is a mixture of polyether diol (A-1) and aliphatic polyesterdiol (A) in a molar ratio of (A-2) / (A-1) = 0.2-5. Method for producing a polyurethane-based elastic fiber characterized in that. The method for producing a polyurethane-based elastic fiber according to claim 1, wherein the molar ratio of the long chain diol (A) and the polyol (B) is in the range of A / B = 5 to 50. The method for producing a polyurethane-based elastic fiber according to claim 1, wherein the organic diisocyanate compound (C) is used such that its molar ratio is in the range of C / A + B = 1.23 to 2.7. The diamine compound (D) as a chain growth agent according to claim 1, wherein a molar ratio of linear diamine (D-1) and cyclic diamine (D-2) is used (D-1) / (D-2) = 2 to Method for producing a polyurethane-based elastic fiber, characterized in that used in the range of 18 mixed. The method of claim 1, wherein the heat resistance improving additive is phosphoryldimethylethanol amine, 2-dimethylaminophenoldiphenyl phosphate, 2-diethylaminoethanolmethyl phosphate, 2-ethylpropylaminophenoldihydrogen phosphate, 2-dibutylamino Method for producing a polyurethane-based elastic fiber, characterized in that selected from phenol dihydrogen phosphate. The method of claim 1, wherein the aliphatic metal salt compound as a sea salt enhancer is a polyurethane-based elastic fiber, characterized in that the metal component is calcium, magnesium or lithium and the fatty acid is composed of saturated and / or unsaturated fatty acids having 10 to 22 carbon atoms Way.