KR102545783B1 - Manufacturing method of sea-island complex fiber, manufacturing method of nonflammable resin including the same and sea-island complex fiber thereby - Google Patents

Abstract

In the method for producing island component resin of the present invention, since the water-soluble resin is included as a sea component, it is possible to reduce the alkalinity through a non-alkali reducing process. Accordingly, there is an effect of maintaining excellent physical properties, dyeability, and flame retardancy of island component fibers.

Description

Manufacturing method of sea-island complex fiber, manufacturing method of nonflammable resin including the same and sea-island complex fiber thereby}

The present invention relates to a method for manufacturing fibers, and more particularly, to a method for manufacturing sea-island composite fibers, a method for manufacturing flame-retardant resin fibers including the same, and sea-island composite fibers manufactured thereby.

In general, curtains, wallpaper, carpets, flame retardant non-woven fabrics, and other ornaments are made of flame retardant treated fabrics and non-woven fabrics for safety in places where people are densely populated, places with many electrical facilities, and places with many enclosed spaces. Therefore, conventional flame retardant yarns are prepared by melt-stretching chemical fiber yarn materials, and then the surface of each chemical fiber yarn is treated with a flame retardant to prevent burning due to a flame or the like. In addition, in the conventional flame retardant treatment method, the synthetic fiber yarn is woven or knitted using a loom or knitting machine to make a fabric, and then the surface of the fabric is treated with a flame retardant to prevent ignition by fire. However, conventionally, since flame retardant treatment is performed after manufacturing synthetic fiber yarns or fabrics, flame retardants are attached to the surface of synthetic fiber yarns or fabrics, so the flame retardant is likely to fall off depending on the time of use, and the flame retardant ability is improved by dropping the flame retardant. It had a downside.

In addition, in the case of flame retardant fibers, they tend to be used in high-quality fabric products, and in the case of products using high-quality fabrics, high color depth is required. / or make fibers. However, in the case of existing flame retardant fibers and/or resins for producing them, there is a problem in that physical properties of flame retardant fibers and/or fabrics prepared by additive compositions and processes for increasing color clarity are reduced. For example, Korean Patent Publication No. 2005-0103617 mentions a flame retardant polyester having excellent color development during dyeing by adding a complementary agent, but hydrolysis of the flame retardant by high-temperature hot water occurs during dyeing. There is Korean Patent Publication No. 2003-0028022 describes a method for producing polyester using cationic dyes, which requires pretreatment of metal sulfonate salts to maintain spinning processability when preparing a polyester composition that can be dyed with cationic dyes. In addition, the process cost increases, and when the content of the modifier is increased to improve color clarity, there is a problem of deteriorating yarn properties and increasing pack pressure during the process.

In addition, conventionally, as a flame retardant polyester sea-island type conjugate fiber, a sea-island type conjugate fiber using an alkali-soluble polyester polymer as a sea component and a flame retardant polyester as an island component has been disclosed. When the alkali reduction process is performed under strong base and high temperature conditions, hydrolysis and flame retardant dropout occur, resulting in deterioration in physical properties, dyeability, and flame retardancy of the final product.

KR 2005-0103617A KR 2003-0028022A

The present invention has been made to solve the above problems, and a method for producing sea-island composite fibers capable of improving flame retardancy and dyeability and reducing weight by water dissolution, a method for producing flame retardant resin fibers including the same, and thereby An object of the present invention is to provide a manufactured sea-island composite fiber.

In addition, another object of the present invention is to provide a method for producing flame retardant resin fibers capable of preventing deterioration of dyeability, physical properties, and flame retardancy of flame retardant fibers even when a weight loss process is performed.

One aspect of the present invention provides a method for producing sea-island composite fibers. The manufacturing method of the island-in-the-sea composite fiber includes a first step of preparing an island component resin and a sea component resin; a second step of drying the island component resin and the sea component resin; and composite spinning of the dried island component resin and sea component resin to produce an island in the sea type composite fiber comprising the island component resin as a sea component and the island component resin as an island component. Step 3; wherein the island component resin is a flame retardant resin containing 90 to 99.5 mol% of polyester and 0.5 to 10.0 mol% of a metal sulfonate; and a flame retardant comprising at least one of a nitrogen-based flame retardant and an inorganic flame retardant containing phosphorus (P); in a weight ratio of 4:1 to 14:1, wherein the sea component resin contains 50 to 50 polyester. 70 mol%, 20 to 30 mol% of an aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms, 10 to 20 mol% of a metal sulfonate, and 10 to 20 mol% of an aliphatic diol.

As a preferred embodiment of the present invention, the nitrogen-based flame retardant includes at least one selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, and melamine pyrophosphate, and the inorganic flame retardant is hydroxylated At least one selected from the group consisting of aluminum, magnesium hydroxide, zinc borate, and zinc diethylphosphinate may be included.

As a preferred embodiment of the present invention, the polyester may be a polyethylene terephthalate (PET) resin having a weight average molecular weight of 18,000 to 22,000.

As a preferred embodiment of the present invention, the composite spinning may be performed at a spinning temperature of 270 to 300 ° C and a spinning speed of 3,000 to 5,000 mpm.

As a preferred embodiment of the present invention, the second step may be performed for 3 to 5 hours at a temperature of 110 to 130 ° C.

As a preferred embodiment of the present invention, in the third step, the island component resin and the sea component resin may be included in a weight ratio of 50:50 to 90:10.

As a preferred embodiment of the present invention, the metal sulfonate is 1 selected from the group consisting of dimethyl 5-sodiosulfo isophthalate, sodium 3,5-dicarbomethoxybenzenesulfonate and dicarbomethoxybenzenesulfonate. May include more than one species.

As a preferred embodiment of the present invention, the aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms may include at least one selected from the group consisting of terephthalic acid, isophthalic acid and dimethyl terephthalate.

As a preferred embodiment of the present invention, the aliphatic diol may include an aliphatic diol having 2 to 20 carbon atoms.

As a preferred embodiment of the present invention, the aliphatic diol is ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethyl glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol , It may include one or more selected from the group consisting of nonamethylene glycol, decamethylene glycol, undecamethylene glycol, dodecamethylene glycol, and tridecamethylene glycol.

Another aspect of the present invention provides a method for producing a flame retardant resin fiber. The manufacturing method of the flame-retardant resin fiber includes the steps of preparing sea-island composite fibers by the method of manufacturing sea-island composite fibers of the present invention; and a fourth step of non-alkali reduction of the sea-island composite fibers.

As a preferred embodiment of the present invention, the above 4 steps may be performed in hot water at a temperature of 80 to 110 ° C for 10 to 50 minutes.

Another aspect of the present invention provides sea-island composite fibers. In the Island in the Sea type composite fiber comprising sea component resin as a sea component and island component resin as an island component, the island component resin contains 90 to 99.5 mol% of polyester and 0.5 mol% of a metal sulfonate. Flame retardant resin containing ~ 10.0 mol%; and a flame retardant comprising at least one of a nitrogen-based flame retardant and an inorganic flame retardant containing phosphorus (P); in a weight ratio of 4:1 to 14:1, wherein the sea component resin contains 50 to 50 polyester. 70 mol%, 20 to 30 mol% of an aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms, 10 to 20 mol% of a metal sulfonate, and 10 to 20 mol% of an aliphatic diol.

The flame retardant resin fiber prepared according to the present invention has improved flame retardancy and dyeability. In addition, the method for producing flame retardant ester fibers of the present invention has an effect of preventing deterioration of dyeability, physical properties, and flame retardancy of flame retardant fibers even if a weight loss process is performed.

1 is a cross-sectional view of an island-in-the-sea yarn according to an embodiment of the present invention.

Hereinafter, in order to explain the present invention in more detail, preferred embodiments according to the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numbers indicate like elements throughout the specification.

A method for manufacturing flame retardant resin fibers according to an embodiment of the present invention includes a first step of preparing island component resin and sea component resin, a second step of drying the island component resin and sea component resin, and a step of drying the island component resin and sea component resin. Step 3 of producing island in the sea type composite fibers including the sea component resin as a sea component and the island component resin as an island component by performing composite spinning on the branch resin, and the island in the sea type composite fiber It involves 4 stages of non-alkaline reduction of fiber.

In the first step, island component resin and sea component resin are prepared. The island component resin is a flame retardant resin containing 90 to 99.5 mol% of polyester and 0.5 to 10.0 mol% of a metal sulfonate; And a flame retardant comprising at least one of a nitrogen-based flame retardant and an inorganic flame retardant containing phosphorus (P); a mixed resin in a weight ratio of 4:1 to 14:1.

The island component resin is a composition formed by the island component, which is a fiber forming component, during production of island-in-the-sea fibers, which will be described later, and corresponds to a composition that forms flame retardant resin fibers remaining after a non-reduction process described later.

In the flame retardant resin, when the polyester is less than 90.0 mol%, fiber formation may be difficult, and when the polyester fiber exceeds 99.5 mol%, the addition amount of the metal sulfonate may be limited. The polyester may be a polyethylene terephthalate (PET) resin having a weight average molecular weight of 18,000 to 22,000.

The metal sulfonate performs thermal action to improve the dyeability of island component resin. In the flame retardant resin, when the amount of the metal sulfonate is less than 0.5 mol%, the effect of improving the dyeability of the island component resin may be limited, and when the amount of the metal sulfonate exceeds 10.0 mol%, the addition amount of the polyester may be relatively limited. .

The metal sulfonate may include at least one selected from the group consisting of dimethyl 5-sodiosulfo isophthalate, sodium 3,5-dicarbomethoxybenzenesulfonate and dicarbomethoxybenzenesulfonate.

By including the metal sulfonate in the polyester, a flame retardant resin having excellent flame retardancy is formed.

At least one of a nitrogen-based flame retardant and an inorganic flame retardant may be further included in the flame retardant resin. The nitrogen-based flame retardant includes at least one selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, and melamine pyrophosphate, and the inorganic flame retardant is aluminum hydroxide, magnesium hydroxide, zinc borate, and It may include at least one selected from the group consisting of zinc diethyl phosphinate (C4H11O2P? 1/2Zn).

Next, the sea component resin is explained. The sea component resin is a component that forms a sea component, which is an extract component from sea-island fibers. The sea component resin is poly containing 50 to 70 mol% of polyester, 20 to 30 mol% of aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms, 10 to 20 mol% of metal sulfonate, and 10 to 20 mol% of aliphatic diol. It may be an ester resin.

The polyester may be a polyethylene terephthalate (PET) resin having a weight average molecular weight of 18,000 to 22,000. When the polyester is less than 50 mol% in the sea component resin, the sea component ratio in the sea-island fibers described later may be smaller than the initial design value. In addition, when the polyester content exceeds 70 mol%, the content of other components may be limited.

The aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms serves to reduce crystallinity. When the amount of the aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms in the sea component resin is less than 50 mol%, the effect of reducing the crystallinity may be reduced, and when the amount of the aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms exceeds 60 mol%, the crystallinity reduction effect may be reduced. In this case, the content values of other components may be limited. The aromatic polyvalent carboxylic acid having 6 to 14 carbon atoms may include at least one selected from the group consisting of terephthalic acid, isophthalic acid and dimethyl terephthalate.

Unlike the metal sulfonate in the island component resin, the metal sulfonate serves to induce adsorption of water molecules, thereby inducing the sea component resin to have water solubility. Specifically, the effect of inducing adsorption of water molecules appears when the island component resin contains 5 to 10 mol%, while the sea component resin contains 20 to 30%. In the sea component resin, when the amount of the metal sulfonate is less than 20 mol%, since the effect of inducing adsorption of water molecules is limited, the amount of the metal sulfonate may not be sufficiently reduced by the non-alkali reduction described later. If exceeded, the content of other components may be relatively limited.

The aliphatic diol may be esterified with the polyester to obtain a polyester resin. In the sea component resin, when the aliphatic diol is less than 10 mol%, the yield of the sea component resin may be low, and when it exceeds 20 mol%, unreacted aliphatic diol may be generated.

The aliphatic diol is an aliphatic diol having 2 to 20 carbon atoms, preferably ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethyl glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, It may include at least one selected from the group consisting of octamethylene glycol, nonamethylene glycol, decamethylene glycol, undecamethylene glycol, dodecamethylene glycol, and tridecamethylene glycol. More preferably, at least one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol and butylene glycol may be included.

In the second step, the island component resin and the sea component resin are dried. The drying step is to improve crystallinity by removing water so that the water content is 100 ppm or less, and drying can be performed at 110 ° C to 130 ° C, preferably at a low temperature of 110 ° C to 120 ° C. can do. At this time, if the drying temperature is less than 110 ° C., the resin may not be sufficiently dried, and if it exceeds 130 ° C., there may be a problem in that the intrinsic viscosity decreases, so it is preferable to perform drying at the above temperature.

In the third step, composite spinning is performed on the dried island component resin and sea component resin to include the sea component resin as a sea component, and the Island in the Sea type including the island component resin as an island component. manufacture of composite fibers.

In addition, the spinning in the spinning step may be performed under a spinning temperature of 270 ° C to 300 ° C and a spinning speed of 3,000 mpm to 5,000 mpm, preferably a spinning temperature of 270 ° C to 290 ° C and a spinning speed of 3,500 mpm to 4,800 mpm It is also possible to perform radiation under At this time, if the spinning temperature is less than 270 ° C, there may be a problem of dyeing (defective dyeing) due to unstretching due to insufficient alignment of the polymer, and if it exceeds 300 ° C, thermal decomposition due to high temperature occurs, resulting in yarn physical properties There may be issues with this degradation. And, if the spinning speed is less than 3,000 mpm, there may be a problem of dyeing (defective dyeing) due to unstretching due to lack of alignment of the polymer, and a cost increase due to a decrease in productivity may occur. If it exceeds 5,000 mpm, there may be a problem of dyeing (defective dyeability) due to unstretching due to lack of alignment of the polymer, and a cost increase due to a decrease in productivity may occur.

In addition, in the present invention, the spinning can be performed using a general sea-island composite spinneret used in the art, and a composite including a sea component spinneret 30 and an island component spinneret 31 as shown in FIG. 1 A spinneret may be used.

In this case, the island component resin and the sea component resin may be mixed in a weight ratio of 50:50 to 90:10. When the island component resin and the sea component resin have a weight ratio of less than 50:50, the flame retardant synergistic effect by the metal sulfonate contained in the island component resin may decrease, and the island component resin and the sea component resin may have a weight ratio of 90:10. If it is exceeded, the weight of the sea component in the sea-island fiber is small, so it may not be possible to see a sufficient effect of preventing the flame retardant component from falling off.

In the fourth step, the non-alkali reduction of the sea-island composite fibers. At this time, the non-alkali reduction is a reduction performed using water, not alkali, and is possible because the above-described sea component resin is water-soluble.

The non-alkali reduction may be performed in hot water at a temperature of 80 to 110 ° C for 10 to 50 minutes. When the temperature of the hot water is lower than 80° C. during weight loss, the rate of weight loss may slow down and the process time may slow down. When the temperature of the hot water exceeds 110° C., side reactions may occur. In addition, if the non-alkali reduction process time is less than 10 minutes, sufficient reduction may not be achieved, so that the sea component may not be completely extracted from the sea-island fibers, and side reactions may occur if the time exceeds 50 minutes.

As the flame retardant water resin fiber prepared by the above-described method for producing flame retardant water resin fiber is reduced by non-alkali reduction rather than alkali reduction, physical properties, dyeability, and flame retardancy of the flame retardant water resin fiber, which is an island component, are reduced. It is possible to provide a fiber having excellent physical properties, dyeability, and flame retardancy.

When the flame retardant water resin fiber of the present invention has an average diameter of 15 μm and an average fineness of 150 de, the rate of change in strength of the composite fiber may satisfy Equation 1 below.

[Equation 1]

In Equation 1, the strength of the composite fiber is measured according to the ASTM D2256 method, the unit of strength is g / d, and the strength change rate is 0.5% to 10%, more preferably 1% to 3% am.

Hereinafter, a preferred embodiment (example) is presented to help the understanding of the present invention. However, the following examples are only for helping understanding of the present invention, and the present invention is not limited by the following experimental examples.

[ Example ]

< Example 1 - Production of flame retardant resin fibers>

(One) Doseong profit( Doseong fiber composition) manufacturing

After mixing 98.7 mol% of polyethylene terephthalate and 1.3 mol% of dimethyl 5-sodiosulfo isophthalate, an esterification reaction was performed while removing water generated at 240°C. Thereafter, the mixture was subjected to a polymerization process at a temperature of 280 to 285° C. and a vacuum degree of 1.5 torr or less to obtain a CD (Cation Dyeable)-based polyester resin through condensation polymerization. And when the intrinsic viscosity (IV) of the prepared CD-based polyester resin was measured with an Ubbelohde viscometer, it was 0.720 dl/g.

Next, zinc diethyl phosphinate (C4H11O2P? 1/2Zn) is added to the CD-based polyester resin at a concentration of 6000 ppm based on the P content with respect to the CD-based polyester resin to obtain P (phosphorus) + Inorganic addition type island component resin (island component resin) was prepared.

(2) exportability profit( sea component fiber composition) manufacturing

Mixing a heat-damaging component resin prepared by copolymerizing a mixture containing 60 mol% of polyethylene terephthalate, 20 mol% of isophthalic acid, 10 mol% of dimethyl 5-sodiosulfo isophthalate, and 10 mol% of diethylene glycol, The intrinsic viscosity (IV) of the prepared sheath resin was 0.820 dl/g.

(3) sea-island fiber manufacturing

After putting the CD-based flame retardant polyester resin in the island portion of the sea-island composite spinneret and the water-soluble resin in the sea portion, spinning was performed under a spinning temperature of 280 ° C and a spinning speed of 4,200 mpm to obtain island-in-the-sea fibers (average diameter of 15 ㎛, average fineness 150 de, core 80% by weight, sheath 20% by weight) was prepared.

(4) Weight loss process

The island-in-the-sea fibers were reduced in hot water (FW) at 98° C. for about 30 minutes to prepare CD-based composite flame retardant polyester fibers.

< comparative example 1 >

It was prepared in the same manner as in Example 1, but fibers were manufactured using only the flame retardant resin when preparing the island component resin.

< comparative example 2 >

It was prepared in the same manner as in Example 1, but fibers were manufactured using only the second island component resin when preparing the island component resin.

< Comparative Example 3 >

Fibers were prepared in the same manner as in Example 1, except that the weight loss process was performed with a 5% aqueous solution of NaOH at a temperature of 98 ° C. for 30 minutes.

< Comparative Example 4 >

Fibers were prepared in the same manner as in Comparative Example 1, except that the weight loss process was performed with a 5% NaOH aqueous solution at a temperature of 98 ° C. for 30 minutes.

< Comparative Example 5 >

Fibers were prepared in the same manner as in Comparative Example 2, except that the weight loss process was performed with a 5% NaOH aqueous solution at a temperature of 98 ° C. for 30 minutes.

< Comparative Example 6 >

Fibers were prepared in the same manner as in Comparative Example 3, except that the weight loss process was performed with a 5% aqueous solution of NaOH at a temperature of 98 ° C. for 30 minutes.

Experimental example : Measurement of physical properties of water-soluble flame retardant fibers

(1) Intensity measurement

The strength of the fiber was measured using an automatic tensile tester (Textechno) at a speed of 50 cm/m and a gripping distance of 50 cm. Strength was defined as elongation as the value (g/de) obtained by dividing the applied load by denier when the fiber was elongated until it was cut by applying a constant force to the strength, and the value (%) expressed as a percentage of the initial length relative to the elongated length. .

And, the strength change rate (%) was measured based on Equation 1 below.

[Equation 1]

In Equation 1 above, the unit of intensity is g/d.

(2) Measurement of weight loss

The mass loss rate of the fiber was measured by measuring the mass of the fiber before and after the weight loss.

After performing the experiment as above, the results are shown in [Table 1].

division Fineness (de) before dyeing after dyeing intensity change rate
(%) weight loss rate
(%) Intensity (g/de) weight (g) robbery
(g/de) weight (g) Example 1 150 3.3 5.61 3.23 5.58 2.12 0.17 Comparative Example 1 150 3.99 5.83 3.96 5.77 1.03 1.03 Comparative Example 2 150 4.13 6.78 4.05 6.72 1.94 0.88 Comparative Example 3 150 - 6.32 - 2.43 - 61.6 Comparative Example 4 150 4.13 6.29 2.38 5.12 42.37 18.6 Comparative Example 5 150 3.99 6.21 3.07 5.16 23.06 16.19

Looking at the experimental results of Table 1, in the case of Example 1, Comparative Example 1, and Comparative Example 2, which were subjected to non-alkali reduction, strength and weight change rates were low, whereas Comparative Examples 1 to 5, which were subjected to alkali reduction In the case of , it can be seen that the strength and weight change rate are high.

In addition, in the case of Example 1 using the island component resin including the flame retardant resin and the second island component resin, it can be seen that the weight loss characteristics are the best.

In the above, the present invention has been described in detail with preferred embodiments and experimental examples, but the present invention is not limited by the above embodiments and experimental examples, and those skilled in the art within the technical spirit and scope of the present invention Various modifications and changes are possible by the person.

30: sea component 31: island component

Claims (13)

Step 1 of preparing island component resin and sea component resin;
a second step of drying the island component resin and the sea component resin; and
Performing composite spinning on the dried island component resin and sea component resin to produce island in the sea type composite fibers containing the island component resin as a sea component and including the island component resin as an island component Including step 3;
The island component resin,
A flame retardant resin containing 90 to 99.5 mol% of polyester and 0.5 to 10.0 mol% of a metal sulfonate; And a flame retardant comprising at least one of a nitrogen-based flame retardant and an inorganic flame retardant containing phosphorus (P); a mixed resin mixed with a weight ratio of 4: 1 to 14: 1,
The sea component resin,
Preparation of sea-island composite fibers containing 50 to 70 mol% of polyester, 20 to 30 mol% of aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms, 10 to 20 mol% of metal sulfonate, and 10 to 20 mol% of aliphatic diol method. According to claim 1,
The nitrogen-based flame retardant includes at least one selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, and melamine pyrophosphate,
The inorganic flame retardant is a method for producing a sea-island composite fiber comprising at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide, zinc borate, and zinc diethylphosphinate. According to claim 1,
The polyester is a polyethylene terephthalate (PET) resin having a weight average molecular weight of 18,000 to 22,000. Method for producing sea-island composite fibers. According to claim 1,
The composite spinning is a method for producing sea-island composite fibers performed at a spinning temperature of 270 to 300 ° C and a spinning speed of 3,000 to 5,000 mpm. According to claim 1,
The second step is a method for producing sea-island composite fibers performed at a temperature of 110 to 130 ° C. for 3 to 5 hours. According to claim 1,
In the third step, the method for producing a sea-island composite fiber comprising the island component resin and the sea component resin in a weight ratio of 50:50 to 90:10. According to claim 1,
The metal sulfonate is a sea-island composite fiber comprising at least one selected from the group consisting of dimethyl 5-sodiosulfo isophthalate, sodium 3,5-dicarbomethoxybenzenesulfonate and dicarbomethoxybenzenesulfonate. Manufacturing method of. According to claim 1,
The method of producing a sea-island composite fiber comprising at least one selected from the group consisting of terephthalic acid, isophthalic acid and dimethyl terephthalate, wherein the aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms. According to claim 1,
The aliphatic diol is a method for producing a sea-island composite fiber comprising an aliphatic diol having 2 to 20 carbon atoms. According to claim 1,
The aliphatic diol is ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethyl glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, A method for producing sea-island composite fibers comprising at least one selected from the group consisting of undecamethylene glycol, dodecamethylene glycol and tridecamethylene glycol. Manufacturing sea-island composite fibers by the method of manufacturing sea-island composite fibers according to any one of claims 1 to 10; and
A method for producing a flame retardant resin fiber comprising a fourth step of reducing the non-alkali of the sea-island composite fiber. According to claim 11,
The fourth step is a method for producing a flame retardant resin fiber performed for 10 to 50 minutes in hot water at a temperature of 80 to 110 ° C. In the island in the sea type composite fiber comprising sea component resin as a sea component and island component resin as an island component,
The island component resin,
A flame retardant resin containing 90 to 99.5 mol% of polyester and 0.5 to 10.0 mol% of a metal sulfonate; And a flame retardant comprising at least one of a nitrogen-based flame retardant and an inorganic flame retardant containing phosphorus (P); a mixed resin copolymerized by mixing in a weight ratio of 4: 1 to 14: 1,
The sea component resin,
A sea-island composite fiber copolymerized with 50 to 70 mol% of polyester, 20 to 30 mol% of an aromatic polyhydric carboxylic acid having 6 to 14 carbon atoms, 10 to 20 mol% of a metal sulfonate, and 10 to 20 mol% of an aliphatic diol .

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