JPH09228152A - Composite fiber - Google Patents

Abstract

(57) Abstract: An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and especially for woven and knitted fabrics having a sufficiently high-class feeling, which is capable of atmospheric pressure disperse dyeing and is rich in softness and drapeability, Further, it is to provide a composite fiber suitable for mixing with a natural fiber. A composite fiber comprising at least two components, an A component and a B component, wherein the A component of the composite fiber is composed of a hot water-soluble polymer and the B component is composed of a hot water-insoluble polymer,
The B component polymer is dyeable at atmospheric pressure and has an average molecular weight of 500-
A composite fiber comprising a polyester obtained by copolymerizing 4000 polyethylene glycol in an amount of 6.0 to 10% by weight, and having a single yarn fineness of 0.5 to 0.05 d after removal of the component A.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite fiber.
More specifically, a hot water-soluble polymer is used as one component, and by removing hot water, an ultrafine fiber having a normal pressure dispersible dyeing property can be obtained, and at the same time, a woven or knitted product having a good texture and a normal pressure dispersible dyeing property. The present invention relates to a composite fiber that can provide

[0002]

2. Description of the Related Art Generally, synthetic fibers such as polyester and polyamide are widely used for clothing and industrial applications because of their excellent properties. Among them, polyester fiber has many excellent features such as strength, dimensional stability, and easy-care property, so that it is used for various purposes including clothing. In particular, ultrafine fibers are excellent in surface quality, drape property, and texture of woven and knitted fabrics, and are being actively developed. As a method for obtaining this ultrafine fiber, there are problems such as spinning in the direct spinning method, yarn breakage during drawing, and difficulty in handling in higher-order processing, and after forming a composite fiber made of a polymer of different components into a fabric, It is well known in the art that it can be obtained by a method in which one component is dissolved and removed, or a separation and division treatment is performed to make it extremely fine. For example, many methods have been proposed for dissolving and removing a part of the alkali-dissolvable polymer by subjecting the composite fibers of components having a different alkali dissolution rate to an alkali treatment after forming a cloth (see, for example, Japanese Patent Laid-Open No. 52-91962). Japanese Unexamined Patent Publication No. 54-6965, JP-A 1-1628
No. 25). However, in order to remove the alkali-soluble polymer with alkali, a special dissolution removal process is required,
It takes a long time to completely remove it, and the sparingly soluble polymer is also damaged by alkali, which is not preferable.

Furthermore, as a method for obtaining ultrafine fibers, a composite fiber technique using a water-soluble polymer is disclosed in, for example, Japanese Patent Laid-Open No. 3-213.
It is disclosed in Japanese Patent No. 564 and Japanese Patent Laid-Open No. 5-247725. These composite fibers obtain ultrafine fibers by dissolving and removing the water-soluble polymer component with hot water, but there is a problem that fusion between single yarns occurs due to heat such as wet heat treatment.

Further, Japanese Unexamined Patent Publication No. 61-296120 discloses a fiber containing hot water-soluble type copolyester as one component. In this technique, no fusion between single yarns was observed due to moist heat treatment or the like, but no atmospheric pressure dyeable composite fiber was obtained. Also, a fabric made of only natural fibers, such as wool,
It can be dyed at normal pressure and has good dyeability and excellent texture and color, but it has poor bulkiness and poor yarn strength, and has wash and wear properties, pleating properties, tailoring, yellowing, insect repellent properties, mold resistance, etc. Is lacking in functionality. For this reason, it has been practiced to use these polyesters, which are lacking in wool and which are excellent in functionality, as a mixture to compensate for these drawbacks.

Polyester can make up for the drawbacks of wool, but because of the difficulty of dyeing polyester, when it is dyed under the same conditions as wool, the color becomes light and the same color as wool cannot be obtained. On the other hand, when dyeing at a temperature of 130 to 135 ° C. which is the usual dyeing temperature of polyester, the same color as wool is obtained, but the texture of wool is impaired, the yellowing is large, and the strength and elongation are greatly reduced. .

Therefore, a dyed product of a mixed fabric of polyester and wool in a problematic state while finding a compromise in terms of the same color property of polyester as wool and the texture, strength and elongation of the mixed wool. Was currently being produced.

In order to solve such a problem, the following atmospheric dyeable polyesters have been proposed. Cationic dye dyeable polyesters obtained by copolymerizing sodium sulfoisophthalic acid in an amount of 5 mol% (8% by weight) or more are disclosed, for example, in JP-A-61-34022, JP-A-60-246847 and JP-A-60-173185. Japanese Patent Laid-Open No. Sho 60-
No. 88190, etc., respectively.

Further, easily dyeable polyester fibers whose fiber internal structure is changed by high-speed spinning at 5000 to 8000 m / min are disclosed, for example, in JP-A-59-59911 and JP-A-58.
It is disclosed in Japanese Patent Publication No. -13739.

Further, an easily dyeable polyester fiber obtained by copolymerizing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an aliphatic diol is disclosed in, for example, JP-A-51-130320 and JP-A-57-30169. Is disclosed in.

However, in any of the disclosed techniques, ultrafine fibers of up to about 1d can be obtained at most, and it is not possible to obtain fibers that are dyeable under normal pressure and have softness, drape, and surface touch. .

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the prior art, and especially for woven and knitted fabrics having a sufficiently high-class feeling, which enables disperse dyeing under normal pressure and is rich in soft feeling and drape. Further, it is to provide a composite fiber suitable for mixing with a natural fiber.

[0012]

The above object of the present invention is a composite fiber comprising at least two components, A component and B component, wherein the A component of the composite fiber is a hot water-soluble polymer and the B component is a heat-soluble polymer. The water-insoluble polymer is composed of a component B polymer which is dyeable under atmospheric pressure and is a polyester obtained by copolymerizing 6.0 to 10% by weight of polyethylene glycol having an average molecular weight of 500 to 4000. Single yarn fineness is 0.5-
It can be achieved with a bicomponent fiber characterized by a value of 0.05d.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION That is, the component A of the composite fiber of the present invention is a hot water-soluble polymer and the component B is a hot water-insoluble polymer. First, the polymer composition of the composite fiber of the present invention will be described.

The hot water solubility referred to in the present invention means the property of being substantially dissolved in an ordinary aqueous solution at 98 ° C.,
There is no problem with using a solubilizing agent such as tripolyphosphoric acid for stable dissolution and removal, and an auxiliary agent for desizing, that is, an activator, an anti-redeposition agent or a weak alkali. Further, hot water insolubility means that it is a property that is not substantially dissolved under the above conditions.

The hot water-soluble polymer is used as the third component 5
-A copolyester obtained by copolymerizing sodium sulfoisophthalic acid with polyethylene terephthalate can be preferably used, but the copolymerization of only 5-sodium sulfoisophthalic acid requires a large amount of copolymerization and may cause a drawback that stretching is difficult. is there. In order to easily stretch the hot water-soluble polymer and improve the hot water solubility, it is desirable to copolymerize the fourth component with the third component. Among the fourth components, isophthalic acid can be preferably used because it does not lower the spinnability and can efficiently improve hot water solubility. That is, as the hot water-soluble polymer, 8 to 14 mol% of 5-sodium sulfoisophthalic acid is used as the third component, and 10 to 10% of isophthalic acid is used as the fourth component.
Copolymerized polyester in which 33 mol% is copolymerized with ethylene terephthalate as a main constituent is preferable. If the copolymerization amount of 5-sodium sulfoisophthalic acid is less than 8 mol%, the solubility in hot water is reduced to 14 mol%.
If the amount is larger, the strength of the composite fiber is likely to be lowered, and the composite fiber is likely to be dissolved even in cold water, so that it may be difficult to handle the yarn in the yarn making and higher steps. Further, if the copolymerization of isophthalic acid is less than 10 mol%, the solubility in hot water is lowered, or insoluble matter is likely to remain during the dissolution treatment, and if it is more than 33 mol%, it is difficult to obtain sufficient spinnability. Defects such as reduced strength may occur.

Next, the component B of the present invention will be described. The atmospheric dyeable polyester used in the present invention has an average molecular weight of 5
Add 0 to 4000 polyethylene glycol to 6.0-1
It must be 0% by weight copolymerized. When the average molecular weight was less than 500, a part of polyethylene glycol added at the time of polymerization of polyester was scattered under the reaction conditions of high temperature and reduced pressure, and the copolymerization rate of polyethylene glycol in polyester was not constant. The physical properties of the polyester raw yarn such as the strength and elongation and the shrinkage ratio vary, and uneven dyeing occurs during dyeing, which is a drawback of the final product. In order to improve the dyeability by copolymerizing polyethylene glycol having a low molecular weight of less than 500,
It is necessary to considerably increase the number of moles of copolymerization as compared with those of high molecular weight, which lowers the softening point of the obtained polyester and the quality of the finally obtained product.

On the other hand, when polyethylene glycol having an average molecular weight of more than 4000 is used, the amount of high molecular weight substances which are not copolymerized in the polyester increases, so that not only the dyeability is lowered but also the dyed fabric is heat treated. At that time, various dye fastnesses are caused, such as bleeding out of dyes and deterioration of light fastness, especially fading fastness.

When the copolymerization rate of polyethylene glycol is less than 6.0% by weight, the dyeability is insufficient and the dyeability under normal pressure cannot be obtained. On the other hand, when it exceeds 10% by weight, the physical properties such as light fastness and alkali resistance are deteriorated even though the dyeability is sufficient, and the quality of the final product is deteriorated.

Since polyethylene glycol is copolymerized with polyester, the resistance to oxidative decomposition tends to be lower than that of ordinary polyester. To improve this, an antioxidant is blended in the polyester. Is preferably performed.

Preferred antioxidants include, for example, hindered phenol compounds which are phenol derivatives having a substituent having a steric hindrance at a position adjacent to a phenolic hydroxyl group. Typical examples of hindered phenolic compounds include 1,3,5-trimethyl-
2,4,6-tri (3,5-tertbutylphenol), 2,6-ditertbutyl-p-cresol,
2,2-methylbis (4-ethyl-6-tertbutylphenol), triethylene glycol-bis [3-
(3-tert-butyl 5-methyl 4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol-
Tetrakis [3- (3,5-di-tert-butyl-4-
Hydroxyphenyl) propionate, octadecyl-
3- (3,5-di-tertbutyl-4-hydroxyphenyl) propionate, 3,5-di-tertbutyl-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2, 4,6-tris (3,5-di-tertbutyl-4-butyl-hydroxybenzyl) benzene and the like can be mentioned.

When the hindered phenolic compound is blended with the polyester, the blending amount is preferably 0.05 to 1.0% by weight based on the polyester from the viewpoint of resistance to oxidative decomposition and prevention of nozzle contamination of the die.

The atmospheric dyeable polyester used in the present invention may be copolymerized with other copolymerization components or blended with other polymers, if necessary, within the range to achieve the object of the present invention. good. For example, a small amount of a chain branching agent such as pentaerythritol, trimethylolpropane, trimellitic acid or boric acid may be copolymerized. In addition to these, optional additives, for example, a matting agent such as titanium oxide, an ultraviolet absorber, a flame retardant, a pigment, etc. may be contained as necessary.

Next, the form of the conjugate fiber of the present invention is preferably a sea-island type because of its ease of handling and easiness of making it ultrafine. Next, the composite ratio (wt%) of the sea component A and the island component B is 50: 50-
It is preferably 5:95. If the sea ratio exceeds 50%, the time required for dissolution and removal will be too long, and if the amount of polymer for dissolution and removal is too large, it will be costly for industrial production, and if the dissolution and removal will exceed 50%. It is not preferable because the density of the woven or knitted material becomes too coarse, which causes problems of quality. On the contrary, if the sea ratio is less than 5%, the desired ultrafine fibers cannot be obtained even if the island components B are fused and the sea is removed. Therefore, the more preferable composite ratio of sea-island components is 30: 7.
It is in the range of 0 to 10:90.

Next, the monofilament fineness of the island component B after the removal of the sea component A is required to be 0.05d or more and 0.5d or less, and preferably 0.2d or less. Soft feeling when 0.5d is exceeded,
If the fineness is not sufficiently exhibited, and if it is less than 0.05d, the softness is overemphasized and the texture becomes slender, which is not preferable.

Next, the cross-sectional shape of the ultrafine fibers has a good texture,
The modified cross-sectional shape is preferable to the ordinary round cross-sectional shape in terms of the ease of imparting surface touch and water absorption. It is more preferable that the fineness and the fineness are mixed as shown in FIG. In addition, there are no strict rules such as 3-leaf, 5-leaf, 8-leaf, flat, elliptical, and star-shaped, but a mixture of these is more preferable.

Next, as one specific method for producing the conjugate fiber of the present invention, a hot-water-soluble polymer is used as the sea component A, and an atmospheric pressure-dispersible dyeable polymer is used as the island component B to obtain the sea-island type composite fiber. it can.

The hot water-soluble polymer is described in detail above. As described above, the main acid component of the hot water-soluble polymer is terephthalic acid, and 5-sodium sulfoisophthalic acid contains 8 to 1 parts.
4 mol%, and isophthalic acid 10-33 mol%
Copolymerized copolyester can be preferably used.

As the normal pressure dispersible dyeable polymer, a polyester obtained by copolymerizing 6.0 to 10% by weight of polyethylene glycol having an average molecular weight of 500 to 4000, as described above, can be preferably used.

In the present invention, as the method for spinning the sea-island type polyester composite yarn, a known composite spinning technique can be adopted. The composite ratio of islands can be arbitrarily selected, but the composite ratio (wt%) of sea islands is 50:50 to 5: due to the relationship between the dissolution and removal properties of sea components and the fusion of island components.
It is preferably 95.

When the sea ratio is 50% or more, the time required for dissolution and removal is too long, and when the amount of the polymer for dissolution and removal is too large, it is disadvantageous in terms of cost for industrial production, and the dissolution and removal of 50% or more is possible. If this happens, the density of the woven or knitted fabric becomes too coarse, which causes a problem of quality, which is not preferable. On the other hand, if the sea ratio is less than 5%, the desired ultrafine fibers cannot be obtained even if the sea components are fused and the sea is removed. Therefore, the more preferable composite ratio of the sea-island components is in the range of 30:70 to 10:90. .

After removing the sea component, the single yarn fineness of the island component is required to be 0.5d or less, preferably 0.2d to 0.05d.
It is. If it is 0.5d or more, the softness and the denseness cannot be sufficiently exhibited, and if it is less than 0.05d, the softness is overemphasized and a slender texture is obtained, and 0.05d or more is preferable.

Next, the cross-sectional shape of the ultrafine yarn is preferably a modified cross-sectional shape rather than a normal round cross-sectional shape because of its good texture, surface touch and ease of imparting water absorption. It is more preferable that the fineness and the fineness are mixed. And 3 leaves, 5
Although there are no strict rules such as leaves, eight leaves, flats, ellipses, and stars, a mixture of these is more preferable.

The composite fiber which is the object of the present invention can be obtained only when the composite fiber composed of the component A and the component B is used.

The thus obtained conjugate fiber can be dissolved and removed by hot water as a woven or knitted product by a conventional method in a usual processing step, that is, a step of desizing and refining. There is no problem in using a weak alkaline agent or the like to the extent that ultrafine fibers are not damaged in order to speed up dissolution and removal.
Subsequently, the ultrafine fibers can be dyed under normal pressure.

As described above, the woven or knitted fabric obtained from the composite fiber of the present invention can be dissolved in sea components by the usual cloth treatment, and thus the normal pressure-dispersible dyeable ultrafine fiber can be easily obtained and 100% thereof can be obtained.
It is possible to provide an ultrafine fiber that can be dispersed under normal pressure, and further to provide a mixed fiber fabric with a high-quality natural fiber that can be dyed without damaging natural fibers, particularly wool and silk, and that has a good texture.

In the examples, the black lightness and light fastness of dyeability are values measured as follows. In the judgment in the table, ◯ means good, Δ means good, and x means bad.

1. <Black lightness> The cloth is scoured, and dyed, washed with water, reduced with water, washed with water, and air-dried under the conditions of 98 ° C described later. Then, the lightness of black color is measured with a multi-source spectrophotometer MSC-2 type (manufactured by Suga Test Instruments Co., Ltd.)
Measure the value (%). (A) Dye: Dianix Black BG-FS (200% product, manufactured by Mitsubishi Kasei Co., Ltd.) Dyeing density: 7% owf Dyeing aid: Nikkasan Salt # 1200 (manufactured by Nika Chemical Industry Co., Ltd.) Dyeing aid Concentration: 0.5 g / l Dyeing bath PH: 6 Dyeing bath ratio: 1/30 (b) Washing with water (D) Washing with water and air-drying The determination of the L value measurement result was as follows. ◯: L value 12.0 to 13.0% △: 〃 13.1 to 15.0% ×: 〃 15.1 or more

2. <Light fastness> Scouring and dry heat setting are carried out in the same manner as in the evaluation method of black lightness.
Then, it is dyed lightly with a red disperse dye under the following dyeing conditions. Dye: Kayacelon Red E-2BL (manufactured by Nippon Kayaku Co., Ltd.) Dye concentration: 0.1% owf Dyeing auxiliary agent, dyeing bath pH, and dyeing bath ratio are the same as those used in the evaluation method for black lightness. The dyeing temperature is 98 ° C. in the case of normal pressure dyeable polyester. Next, rinse with running water
Air dry, JIS-L0842 (carbon arc lamp method third
The light fastness is measured according to the exposure method). Grade 5 is the one with less discoloration and discoloration of the dyed product due to arc lamp irradiation,
Judgment is made in 5 grades up to grade 1 (inferior). The determination of the light fastness measurement result was as follows. ○: Grade 5 △: 〃 Grade 4 ×: 〃 Grade 3 or less

[0039]

The present invention will be described in more detail with reference to the following examples. Example 1 Copolyester chip containing 12 mol% 5-sodium sulfoisophthalic acid, and 25 mol% isophthalic acid, and 0.05 wt% titanium oxide and 0.7 wt% lithium acetate (melt viscosity at 290 ° C. : 15
00 poise, softening point: 130 ° C.) dried under reduced pressure at 100 ° C. for 10 hours as components A and B as dimethyl terephthalate 100 parts, ethylene glycol 80 parts, antioxidant Irganox-1010 (manufactured by Ciba Geigy) ) 0.3 parts, 0.01 parts of dimethylpolysiloxane (silicone oil manufactured by Toshiba Silicone Co., Ltd.), 0.04 parts of cobalt acetate and 0.04 parts of antimony trioxide are heated to 130 ° C to 230 ° C. After distilling off methanol to cause a transesterification reaction, 8.8 parts of polyethylene glycol having an average molecular weight of 1000 was added, and further 230 ° C.
And reacted for 30 minutes. Thereafter, 0.03 parts of trimethyl phosphate was added, and 5 minutes later, 0.05 parts of titanium dioxide was added as a 20% by weight ethylene glycol slurry to obtain a low polymer. The obtained low polymer is further added to 2
While gradually raising the temperature from 30 ° C. to 280 ° C. and gradually reducing the pressure from atmospheric pressure to a high vacuum of 1 mmHg or less, polycondensation was performed to obtain a modified polyethylene terephthalate having a softening point of 257 ° C. The copolymerization rate of polyethylene glycol having an average molecular weight of 1000 in the polyester thus obtained was 8.0% by weight.

By the same method as described above, chips were obtained in which only the copolymerization rate of polyethylene glycol was changed to 0 to 12%. For comparison, a chip having an average molecular weight of PEG of 200 and 5000 and a PEG copolymerization rate of 8 wt% was prepared.

The obtained A and B component chips were dried by a conventional method, and each was compounded in a sea-island type by a conventional composite spinning machine with a composite ratio of A and B components of 15:85 (weight ratio). Stretching was performed to obtain 75-36 sea-island type composite fibers of 8 islands. As shown in FIG. 1, the cross-sectional shape of the island component B was a mixture of oval, fan-shaped and thick and thin. This fiber was woven into habutae by a conventional method, and then passed through a 98 ° C. scouring bath (NaOH: 0.1%, tripolyphosphoric acid: 0.2 g / l, surfactant: 2 g / l) A The components were eluted and removed, and dyeing was performed. The dyeing was performed under the conditions of black disperse dye 7% owf, 98 ° C. and 60 minutes without using a carrier. After dyeing, it was soaped at 70 ° C. for 20 minutes in a weak alkaline bath containing 1 g / l of soda ash and 0.5 g / l of a nonionic detergent and washed with water.

The blackness of the dyed product was measured by the above-described colorimetric method. The dyeing degree was measured by dyeing with the above-mentioned dark blue disperse dye. The light fastness (class) was measured by dyeing with the red disperse dye. Table 1 shows the evaluation results of the obtained composite fiber before and after scouring, such as yarn formability, weavability, component A solubility, dyeability, and product quality. The average fineness of the ultrafine fibers after the dissolution of the component A was 0.1 d.

[0043]

[Table 1] Level No. 2, 3 and 4 are the present invention. As is apparent from Table 1, the dyeing products of the ordinary pressure-dispersible dyeable ultrafine fiber cloth of the present invention, in which 6.0% by weight of polyethylene glycol having an average molecular weight of 1000 is copolymerized, are It had better color development and light fastness than polymerized products, was soft and excellent in drape, and had smooth and moderate tension and elasticity.

Level No. Nos. 1, 5, 6, 7, and 8 are comparative examples for clarifying the present invention. No. 1 was a case where a pomopolymer was used as the B component, and as a matter of course, it was not possible to perform dyeing under normal pressure dispersion. No. In No. 5, when the copolymerization rate of polyethylene glycol having an average molecular weight of 1000 was set to 4.0% by weight, the dyeability was insufficient. No. 6 is an average molecular weight of 1000
The polyethylene glycol copolymerization rate was 12% by weight, and the light fastness was poor. No. In No. 7, when the copolymerization rate of polyethylene glycol having an average molecular weight of 200 was set to 8.0% by weight, uneven dyeing occurred and the product quality was poor. No. No. 8 was a case where the copolymerization rate of polyethylene glycol having an average molecular weight of 5000 was 8.0% by weight, and the dyeability was lowered and the fastness was also poor.

Example 2 In accordance with Example 1, the discharge amount was changed so that the average single yarn fineness of the component B was as shown in Table 2, and yarn making, weaving, scouring, and atmospheric dyeing were carried out. The results are shown in Table 2.

[0046]

[Table 2] Level No. In the present invention, Nos. 10 to 12 were good in yarn formability-weavability, component A solubility, dyeability, product quality, and texture. No. Nos. 9 and 13 are comparative examples for clarifying the present invention. No. 9 lacked the soft feeling and texture peculiar to ultrafine fibers, and conversely No. 9 No. 13 had a soft texture because the softness was emphasized too much.

Example 3 According to Example 1, the composite ratio (weight) of the A and B components was changed so that the composite ratio of the A / B components was as shown in Table 3, and the yarn making, weaving,
Scouring and atmospheric dyeing were performed. The results are shown in Table 3.

[0048]

[Table 3] Level No. Nos. 14 to 16 are products of the present invention. No. 14 was not perfect in yarn-forming property, weaving property, dyeing property, product quality and texture, but was in an acceptable level. No. Sample No. 16 was not sufficiently satisfactory in terms of A component solubility, product quality, and texture, but reached an acceptable level. No. No. 15 was satisfactory in all aspects.

[0049]

EFFECTS OF THE INVENTION The composite fiber of the present invention can easily remove sea components, has excellent dyeability even as an ultrafine fiber, has soft dry touch and drape properties, and has hot water solubility,
Since it becomes an ultrafine fiber that can be dispersed under atmospheric pressure, it is suitable for blending with natural fibers and is the most suitable material for high-quality clothing that has never been obtained before. In addition, ultrafine fibers excellent in dyeability can be obtained without any problems in processability and solubility of sea components, and high-quality clothing can be achieved.

[0050]

[Detailed Description of Drawings]

[0051]

FIG.

[0052]

[Explanation of symbols]

 1: A component 2: B component

Claims (4)

[Claims] 1. A composite fiber comprising at least two components, an A component and a B component, wherein the A component of the composite fiber is a hot water-soluble polymer and the B component is a hot water-insoluble polymer.
The B component polymer is dyeable at atmospheric pressure and has an average molecular weight of 500-
A composite fiber comprising a polyester obtained by copolymerizing 4000 polyethylene glycol in an amount of 6.0 to 10% by weight, and having a single yarn fineness of 0.5 to 0.05 d after removal of the component A. 2. The composite fiber is a sea-island type sea component A and island component B.
The composite fiber according to claim 1, characterized in that the composite ratio thereof is 50:50 to 5: 95% by weight. 3. The composite fiber according to claim 1 or 2, wherein the ultrafine fibers of the island component B have an irregular cross-sectional shape. 4. The main acid component of the hot water-soluble polymer of the component A is composed of terephthalic acid, containing 8 to 14 mol% of 5-sodium sulfoisophthalic acid and 1 of isophthalic acid.
The conjugate fiber according to any one of claims 1 to 3, which is a copolyester copolymerized with 0 to 33 mol%.