KR20110079165A - Anti-chlorine spandex fiber and preparation method thereof containing phosphorus anti-oxidant - Google Patents

Abstract

PURPOSE: A spandex fiber with excellent chlorine resistance including phosphorus antioxidant and a manufacturing method thereof are provided to present original property of matter of a polyurethane polymer by manufacturing spandex containing inorganic antichlorine material in the phosphorus antioxidant and application phase. CONSTITUTION: The polyurethane polymer includes 0.1 - 5% weight of phosphorus antioxidant and 0.1 - 10% weight of inorganic antichlorine material. The phosphorus antioxidant is selected from a group consisting of tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenyl diphospho night, tris (2,4-di-t-butylphenyl) phosphate and tris (3-t-butyl-4-hydroxyphenyl) phosphate. The inorganic antichlorine material is selected from a group consisting of aliphatic alcohol, fatty acid, fatty acid salt, aliphatic ester, phosphoric ester, styrene/maleic anhydride copolymer and their derivative, silane coupling agent, titanate coupling agent, polyorganosiloxane, polyorganohydrogensiloxane and melamine based compound.

Description

Anti-chlorine Spandex Fiber and Preparation Method including Containing Phosphorus Anti-oxidant

The present invention relates to a spandex containing a phosphorus antioxidant and an inorganic chlorine agent, and more particularly, to a spandex and a method for producing the chlorine resistance improved while maintaining the conventional physical properties of the polyurethane-based polymer.

Spandex, which is a typical polyurethane elastic fiber, maintains high rubber elasticity and is excellent in physical properties such as tensile stress and recovery property.

However, polyurethane, which is a major component of spandex, exhibits considerable physical property degradation when washing with chlorine bleach. Swimsuits made by alternating spandex and polyamide have a chlorine content of 0.5 to 3.5 ppm or more. Contact with the pool will degrade the physical properties of the spandex, such as strength.

Efforts have been made to improve the resistance of spandex fibers to chlorine-induced deterioration. As a chlorine resistant agent used in spandex, zinc oxide is disclosed in U.S. Patent No. 4,340,527, and Huntite and U.S. Patent No. 5,626,960. A mixture of hydromagnesite, patent 92-03250, calcium carbonate and barium carbonate, Japanese Patent Laid-Open No. 6-81215, MgO / ZnO solid solution, Japanese Patent Publication No. 59-133248 discloses magnesium oxide, magnesium As for hydroxide or hydrotalcite, Japanese Patent Laid-Open No. 3-292364 discloses hydrotalcite treated with a higher fatty acid and a silane coupling agent, respectively. Phenol-based additives are also added to improve the chlorine resistance and the physical properties of spandex. Japanese Patent Application No. 50-004387 discloses a phenolic additive as a stabilizer for spandex, and US Pat. No. 6,846,866 discloses an improvement in chlorine resistance and discoloration due to combustion by mixing an inorganic additive and an organic additive. .

The present invention has been made to solve the above problems, by producing a spandex containing a phosphorus antioxidant and an inorganic chlorine-resistant agent in the application step, the spandex fiber with improved chlorine resistance while showing the inherent physical properties of the polyurethane polymer and its production It is an object to provide a method.

The excellent chlorine-resistant spandex fiber including the phosphorus antioxidant according to the present invention is characterized in that it comprises 0.1 to 5% by weight of phosphorus antioxidant and 0.1 to 10% by weight of inorganic chlorine resistant agent.

According to the present invention, a method for preparing a spandex fiber having excellent chlorine resistance including a phosphorus antioxidant is prepared by reacting an organic diisocyanate and a diol to prepare a polyurethane precursor, and then dissolving the polyurethane precursor in an organic solvent. Preparing a polyurethane solution prepared by reaction with; And spinning to the polyurethane solution by adding 0.1 to 5% by weight of phosphorus antioxidant and 0.1 to 10% by weight of an inorganic chlorine agent based on the polyurethane polymer.

Spandex according to the present invention can be improved chlorine resistance while maintaining the conventional physical properties. In addition, the spandex according to the present invention can be effectively used in sports clothing such as underwear or socks, especially swimwear because of excellent discoloration and chlorine resistance.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The 'phosphorus antioxidant' used in the present invention means a trivalent phosphorus compound including a structure of phosphate, phosphonate, phosphonite, and the like.

Specific examples of the phosphorus antioxidant include tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenyldiphosphonite, tris (2,4-di-t-butylphenyl) phosphate, bis ( 2,4-di-t-butylfetyl) pentatriitol diphosphite), tris (3-t-butyl-4-hydroxyphenyl) phosphate and the like.

Examples of chemical structures of phosphorus antioxidants are shown below.

Tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenyldiphosphonite (phosphorus antioxidant-1)

Tris (2,4-di-t-butylphenyl) phosphate (phosphorus antioxidant-2)

Bis (2,4-di-t-butylfetyl) pentaerythritol diphosphite (phosphorus antioxidant-3)

On the other hand, as a chlorine-resistant inorganic chlorine agent, a physical mixture of hydrotalcite, huntite and hydromagnesite, and inorganic chlorine agents such as basic magnesium carbonate, zinc oxide, and magnesium oxide have the property of trapping halogens. Very effective.

M ^{2 +} _x Al ₂ (OH) _y (A ^n- ) _z O _k MH ₂ O (hydrotalcite)

[Wherein, M ^{2 +} is Mg ^{2 +,} Ca ^{2 +} or Zn ^{2 +} a, A ^{n -} is an anion having a valence of n, x, y are two or more positive values, Z is a positive value equal to or less than 3, k is a positive number of 0 or more than 3, m is 0 or a positive number, a ^{n -} is ^{OH -, F -, Cl -} , Br -, NO 3 -, SO 4 2 -, CH 3 COO -, CO 3 2 -, HPO ₄ ^{2 -,} oxalate ion, salicylate ion, silicate ion or Im.

Non-limiting examples of the hydrotalcite compound of Formula 1 include Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O, Mg ₆ Al ₂ (OH) ₁₆ CO ₃ · 5H ₂ O, Mg ₈ Al ₂ ( OH) ₂₀ CO _{3 · 6H 2 O, Mg 4 Al} 2 (OH) 12 CO 3 · 3H 2 O, Mg 4 .5 Al 2 (OH) 13 CO 3, Mg 6 Al 2 (OH) 16 CO 3, Mg 8 Al 2 (OH _{) 20 CO 3, Mg 4 Al} 2 (OH) 20 CO 3, Mg 4 .5 Al 2 (OH) 13 (CO 3) 0.6 O 0 .4, Mg 6 Al 2 (OH) 16 (CO 3) 0.7 O _{0, 0.3,} include _{Mg 4.5 Al 2 (OH) 12.2} (CO 3) 0.8 O 0.6, Mg 4 Al 2 (OH) 12 (CO 3) 0.6 O 0 .4 and any mixture thereof.

Hydrotalcite has a feature of absorbing moisture, and when it is added to a polyurethane polymer without coating, gel generation and aggregation may occur and cause trimming in the spinning process. Coating hydrotalcite can be used to prevent water absorption of hydrotalcite and to improve dispersibility to improve the release pressure and trimming during the spinning process. Even in the case of using uncoated hydrotalcite, when the sand grinding or milling is performed, the same radioactivity can be obtained as in the case of using the coated hydrotalcite.

Examples of the hydrotalcite coating agent include aliphatic alcohols, fatty acids, fatty acid salts, aliphatic esters, phosphate esters, styrene / maleic anhydride copolymers and derivatives thereof, silane coupling agents, titanate coupling agents, polyorganosiloxanes, Polyorganohydrogensiloxane, melamine type compounds, and the like. The coating agent is preferably a fatty acid, fatty acid salt and / or melamine based compound. In the case of fatty acids or fatty acid salts, the effectiveness of the coating is superior to other coating materials. In the coating of hydrotalcite, an appropriate amount of coating agent is added to a solvent such as water, alcohol, ether, dioxane, and the like so that the amount of the coating agent is 0.1 to 10% by weight based on the weight of hydrotalcite, and then uncoated hydrotalcite is added. The temperature is increased and stirred for 20 minutes to 2 hours at 60 to 180 ° C. (using a high pressure reactor if necessary), followed by filtering and drying after stirring. Another method is a method in which the coating agent is heated and dissolved without solvent, and then mixed with hydrotalcite at a high speed to coat the coating agent.

In the present invention, the fatty acid used as the coating agent of the hydrotalcite is preferably one or two or more selected from monovalent or polyvalent fatty acids of straight or branched chain hydrocarbons having 3 to 40 carbons. Examples of specific fatty acids are lauric acid, caproic acid, palmitic acid, stearic acid.

Fatty acid salts include metals or zinc selected from the group I to III of the periodic table. Fatty acids of the fatty acid salts may be saturated or unsaturated, may contain 6 or more and 30 or less carbon atoms, and may be monofunctional or difunctional. Examples of fatty acid salts are the lithium, magnesium, calcium, aluminum or zinc salts of oleic acid, palmitic acid or stearic acid, preferably magnesium stearate, calcium stearate or aluminum stearate, more preferably magnesium stearate .

The melamine-based compound used as the coating agent in the present invention is a melamine compound, a melamine compound in which phosphorus (P) is bonded, a melamine cyanurate compound, a melamine compound substituted with an organic compound having a carboxyl group, an organic compound having a carboxyl group, and phosphorus It is preferable to use the melamine cyanurate compound substituted with the melamine compound (P) couple | bonded and the organic compound which has a carboxyl group individually or in mixture.

The melamine compound is methylene dimelamine, ethylene dimelamine, trimethylene dimelamine, tetramethylene dimelamine, hexamethylene dimelamine, decamethylene dimelamine, dodecamethylene dimelamine, 1,3-cyclohexylene dimelamine, p- Phenylene dimelamine, p-xylene dimelamine, diethylene trimelamine, triethylene tetramelamine, tetraethylene pentamelamine, hexaethylene heptamelamine, melamine formaldehyde, etc. can be selected.

Mg ₃ Ca (CO ₃ ) ₃ (Huntite)

_{Mg 4 (CO 3) 4 Mg} (OH) 2 · 5H 2 0 ( hydro magnesite)

The huntite and hydromagnesite are present in the form of a mixture when present as a mineral, and it is difficult to separate them into pure huntite or pure hydromagnesite.

_{^{M 2 + x (A n -}} ) y M 2 + (OH) z · mH 2 0 ( hydro magnesite)

[Wherein, M ^{2 +} is Mg ^{2 +} or Ca ^{2 +,} A ^{n -} is CO ₃ ^{2 -,} x is 1 ~ 5, z is 0 ~ 2, m is 0 to 5;

The hydromagnesite can also be obtained as a mineral and can also be obtained through synthesis. Examples of coatings that can be used for hydromagnesite include aliphatic alcohols, fatty acids, fatty acid salts, aliphatic esters, phosphate esters, styrene / maleic anhydride copolymers and derivatives thereof, silane coupling agents, titanate coupling agents, polyorganosiloxanes, polyors It includes, but is not necessarily limited to, one or more selected from the group consisting of ganohydrogensiloxane and melamine-based compounds. The coating agent is preferably a fatty acid, fatty acid salt and / or melamine based compound. In the case of fatty acids or fatty acid salts, the effect of the coating is superior to other coating materials. In the coating of hydromagnesite, an appropriate amount of coating agent is added to a solvent such as water, alcohol, ether, dioxane, etc. so that the amount of coating agent is 0.1 to 10% by weight based on the weight of hydromagnesite, the uncoated hydromagnesite is added, and then the temperature is increased. After stirring for 10 minutes to 2 hours at 50 ~ 170 ℃ (using a high-pressure reactor if necessary), after stirring and made through a filtering and drying process. As another method, the coating agent is heated and dissolved without solvent, and then mixed with hydromagnesite at a high speed to coat.

In the case of coating with a melamine-based compound, since the melting point of the melamine-based compound is high, it should be coated under pressure at 150 ° C or higher in water.

In the present invention, the fatty acid used as the coating agent of the hydromagnesite is preferably one or two or more selected from monovalent or polyvalent fatty acids of straight or branched chain hydrocarbons having 3 to 40 carbons. Examples of specific fatty acids are lauric acid, caproic acid, palmitic acid, stearic acid.

Fatty acid salts are metals selected from Groups I to III of the Periodic Table or include zinc. Fatty acids of fatty acid salts may be saturated or unsaturated, may contain from 6 to 30 carbon atoms, and may be monofunctional or difunctional. Examples of fatty acid salts are the lithium, magnesium, calcium, aluminum or zinc salts of oleic acid, palmitic acid or stearic acid, preferably magnesium stearate, calcium stearate or aluminum stearate, more preferably magnesium stearate .

Polyurethane polymers used in the preparation of the spandex according to the present invention, as is known in the art, is prepared by reacting an organic diisocyanate and a polymer diol to prepare a polyurethane precursor, which is dissolved in an organic solvent and then diamine and mono Prepared by reacting with an amine. Organic diisocyanates used in the present invention include diphenylmethane-4,4'- diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, butylene diisocyanate, hydrogenated diphenylmethane-4,4'- diisocyanate, and the like. have. In addition, polytetramethylene ether glycol, polypropylene glycol, polycarbonate diol, or the like may be used as the polymer diol. Diamines are used as chain extenders and include, for example, ethylenediamine, propylenediamine, hydrazine and the like. On the other hand, monoamine is used as a chain terminator, for example, diethylamine, monoethanolamine, dimethylamine, and the like.

The present invention is intended to prevent discoloration or deterioration of physical properties of the spandex due to heat treatment during the processing of the spandex or other ultraviolet rays, atmospheric smog and the like, and is based on phenol compounds, benzofuran-one compounds, semicarbazide compounds, and benzotria. Sol-based compounds, hindered amine compounds, polymeric tertiary amine stabilizers (e.g., polyurethanes with tertiary nitrogen atoms, polydialkyl aminoalkyl methacrylates) and the like can be added to the polyurethane polymer. .

In addition to the above components, the spandex of the present invention may further include an inorganic additive such as titanium dioxide and magnesium stearate. Titanium dioxide can be used in the range of 0.1 to 5% by weight, depending on the whiteness of the fiber. In addition, magnesium stearate may be used in the range of 0.1 to 2% by weight, which is added to improve the dissolvability of spandex.

In the present invention, the amount of phosphorus antioxidant added is preferably 0.1 to 5% by weight relative to the polyurethane polymer. When the amount is less than 0.1% by weight, the property of contributing to the improvement of the chlorine resistance of the spandex is small. It is not preferable because there is no improvement effect.

The present invention is characterized in that it comprises 0.1 to 10% by weight of an inorganic chlorine-resistant agent in the application step in order to achieve the above technical problem. The present inventors were able to produce spandex fibers with improved chlorine resistance by miniaturizing the particles of the inorganic chlorine agent by using the sand grinding device used in the step in preparing a slurry for injecting the polyurethane polymer.

In the present invention, the addition amount of the inorganic chlorine resistant agent is preferably 0.1 to 10% by weight compared to the polyurethane polymer, when less than 0.1% by weight is less than the property of imparting chlorine resistance to the spandex, when exceeding 10% by weight excessive inorganic It is not preferable because the content lowers the strength, elongation and modulus of spandex.

In preparing the spandex of the present invention, the phosphorus antioxidant and the inorganic chlorine resistant agent may be added to the polyurethane polymer at any convenient time. For example, the inorganic chlorine resistant agent may be added to the solution together with other additives and mixed with the polyurethane polymer during the sand grinding or milling process, and sand grinding or milling in the solvent separately from the other additives. May be mixed with the polyurethane polymer during the process. In addition, the phosphorus antioxidant may also be added during the sand grinding or milling process, may be added separately dissolved in a solvent.

In the present invention, the inorganic chlorine resistant agent may be coated or uncoated with a coating agent commonly used in the art, and the coating does not affect the discoloration resistance and the chlorine resistance of the spandex yarn.

The process of sand grinding or milling the inorganic chlorine agent is performed by mixing the inorganic chlorine agent, the solvent and a small amount of the polyurethane polymer using a conventional bead mill, and milling the particles to be smaller, or hydrotalcite or solvent. , Other additives and a small amount of polyurethane polymer may be mixed to form a slurry to mill to make the particles smaller. Here, a small amount of polyurethane polymer serves to improve the dispersibility of the inorganic chlorine agent. As a solvent, 1 or more types of dimethylacetamide, dimethylformamide, and dimethyl sulfoxide can be selected and used.

Under the above conditions, the present inventors confirmed that the hydrotalcite partially dehydrated also had no problem in the spandex manufacturing process when milling in order to reduce the particle size.

The present inventors also did not find any difference between the coating and the coating during the spandex manufacturing process when milling hydrotalcite to make the particles smaller under such conditions.

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

≪ Example 1 >

518 g of diphenylmethane-4,4′-diisocyanate and 2328 g of polytetramethylene ether glycol (molecular weight 1800) were reacted with stirring at 90 ° C. for 95 minutes in a nitrogen gas stream to prepare a polyurethane prepolymer having an isocyanate at the sock end. It was. After cooling the prepolymer to room temperature, 4269 g of dimethylacetamide was added to dissolve to obtain a polyurethane prepolymer solution.

Next, 43 g of ethylenediamine and 9.1 g of diethylamine were dissolved in 1889 g of dimethylacetamide and added to the prepolymer solution at 9 ° C. or lower to obtain a polyurethane solution. 1% by weight of poly (N, N-diethyl-2-aminoethyl methacrylate) as a dye enhancer as an additive relative to the solid content of the polymer, 0.1% titanium dioxide as a light-resistant agent, 0.26% by weight magnesium stearate as a disintegration enhancer, and 2% by weight of stearic acid and 1% by weight of melamine polyphosphate as a chlorinating agent, and ₄ % by weight of hydrotalcite Mg ₄ Al ₂ (OH) ₁₂ CO ₃ · 3H ₂ O coated with 1% by weight. Further, 1.5 wt% of (tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenyldiphosphonite) was added and mixed as a phosphorus antioxidant in the slurry to obtain a spinning solution.

After degassing the spinning stock solution, the spinning temperature was 260 ° C. in the dry spinning process, and the winding speed was wound at 900 m / min to prepare 3 filament 40 denier spandex yarn, and its chlorine resistance was evaluated and shown in Table 1 below.

In order to evaluate the chlorine resistance of the obtained spandex yarn, strong retention in chlorine water was evaluated by the following method.

The spandex yarn was treated for 1 hour in water at pH 4.5 and 99-100 ° C. under 50% elongation, dried and cooled at room temperature, immersed in 45 L chlorine water at 3.5 ppm of active chlorine and pH 7.0-7.5 at room temperature for 120 hours. The intensity retention was calculated by the following equation. MEL was used for the strength evaluation, and the sample length was 20 cm and measured at a cross head speed of 1000 mm / min using a cell of 32 kgf.

Strong retention (%) = S / S _o × 100

(S _o : Strong before treatment, S: Strong after treatment)

≪ Example 2 >

A spandex yarn was prepared using the same polymer as in Example 1 except that the phosphorus antioxidant (tris (2,4-di-t-butylphenyl) phosphate) was used, and the chlorine resistance thereof was evaluated. It is shown together in Table 1.

<Example 3>

Hydrophosphite that was coated with phosphorus antioxidant (bis (2,4-di-t-butylfetyl) pentaerythritol diphosphite) and not coated as a chlorine-resistant Mg ₄ Al ₂ (OH) ₁₂ CO ₃ · 3H Except for the addition of 4% by weight of ₂ O using the same polymer as in Example 1 to prepare a spandex, to evaluate the chlorine resistance and the results are shown in Table 1 together.

<Example 4>

Except for the inorganic chlorine agent using a mixed mineral of huntite and hydromagnesite was prepared spandex yarn using the same polymer as in Example 1, and evaluated the chlorine resistance and the results are shown in Table 1 together.

<Example 5>

Except for the use of hydromagnesite as an inorganic chlorine-resistant agent was prepared spandex yarn using the same polymer as in Example 1, and evaluated the chlorine resistance and the results are shown in Table 1 together.

<Comparative Example 1>

Except for using a hydroxy phenyl-based compound without using a phosphorus antioxidant, to prepare a spandex yarn using the same polymer as in Example 1, to evaluate the chlorine resistance and the results are shown in Table 1 together .

<Comparative Example 2>

Except for using only inorganic chlorine-resistant oxidizing agent without using a phosphorus-based antioxidant, was prepared spandex yarn using the same polymer as in Example 1, and evaluated the chlorine resistance and the results are shown in Table 1 together.

division Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Strong retention rate (%) 80.3 78.0 77.5 79.1 77.6 56.7 63.8

As confirmed through the results of Table 1, the spandex of the present invention including both phosphorus antioxidant and inorganic chlorine-resistant, using only inorganic chlorine-resistant or salt-resistant compared to the conventional spandex containing a hydroxy phenyl-based compound Strong retention in the minority has been significantly improved.

Although the embodiments of the present invention have been described in detail above, these are merely for illustrative purposes and should not be construed as limiting the present invention. It will be apparent to those skilled in the art that many variations and modifications of the above embodiments are possible without departing from the spirit and scope of the invention. The protection scope of the invention should be defined by the appended claims and their equivalents.

Claims (7)

An excellent chlorine resistance spandex fiber comprising a phosphorus antioxidant, characterized in that it comprises 0.1 to 5% by weight of a phosphorus antioxidant and 0.1 to 10% by weight of an inorganic chlorine resistant agent based on the polyurethane polymer. The method of claim 1, wherein the phosphorus antioxidant is tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenyldiphosphonite, tris (2,4-di-t-butylphenyl) phosphate And spandex fibers having excellent chlorine resistance, including at least one member selected from the group consisting of tris (3-t-butyl-4-hydroxyphenyl) phosphate. The -t-butyl-4-hydroxy compound according to claim 1, wherein the inorganic chlorine agent is at least one selected from the group consisting of a hydrotalcite compound, a huntite and hydromagnesite mixed mineral, hydromagnesite, zinc oxide, and magnesium oxide. Spandex fiber excellent in chlorine resistance, including a phosphorus antioxidant, characterized in that at least one member selected from the group consisting of phenyl) phosphate. The method of claim 3, wherein said hydrotalcite compound is _{Mg 4 .5 Al 2 (OH)} 13 CO 3 · 3.5H 2 O, Mg 6 Al 2 (OH) 16 CO 3 · 5H 2 O, Mg 8 Al 2 ( OH) ₂₀ CO ₃ 6H ₂ O, Mg ₄ Al ₂ (OH) ₁₂ CO ₃ 3H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ , Mg ₆ Al ₂ (OH) ₁₆ CO ₃ , Mg ₈ Al ₂ (OH) ₂₀ CO ₃ , Mg ₄ Al ₂ (OH) ₂₀ CO ₃ , Mg _4.5 Al ₂ (OH) ₁₃ (CO ₃ ) _0.6 O _0.4 , Mg ₆ Al ₂ (OH) ₁₆ (CO ₃ ) _0.7 O ₀ And _third, the _{Mg 4 .5 Al 2 (OH)} 12.2 (CO 3) 0.8 O 0 .6, and _{Mg 4 Al 2 (OH) 12} (CO 3) at least one member selected from the group consisting of O _{0.6 0.4} Spandex fiber with excellent chlorine resistance, including a phosphorus antioxidant. The method of claim 3, wherein the hydromagnesite is Mg ₄ (CO ₃ ) ₄ · Mg (OH) ₂ · 4H ₂ O, Mg ₃ (CO ₃ ) ₃ · Mg (OH) ₂ 3H ₂ O, Mg ₄ (CO _{3 4} ) Mg (OH) ₂ , Mg ₃ (CO ₃ ) ₃ , Mg (OH) ₂ , MgCO ₃ Spandex fiber with excellent chlorine resistance including a phosphorus-based antioxidant, characterized in that at least one selected from the group consisting of . The method of claim 1, wherein the inorganic chlorinating agent is aliphatic alcohol, fatty acid, fatty acid salt, aliphatic ester, phosphate ester, styrene / maleic anhydride copolymer and derivatives thereof, silane coupling agent, titanate coupling agent, polyorganosiloxane And excellent chlorine-resistant spandex fiber comprising a phosphorus-based antioxidant, characterized in that the coating by at least one coating agent selected from the group consisting of polyorganohydrogensiloxane and melamine-based compounds. Preparing a polyurethane solution by reacting an organic diisocyanate and a diol to prepare a polyurethane precursor, and then dissolving the polyurethane precursor in an organic solvent and then reacting with a diamine and a monoamine to prepare a polyurethane solution. And Excellent chlorine resistance, including a phosphorus-based antioxidant, comprising the step of spinning by adding 0.1 to 5% by weight of phosphorus antioxidant and 0.1 to 10% by weight of inorganic chlorine-based antioxidant to the polyurethane solution Method for producing spandex fiber.